Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull module updates from Rusty Russell:
"Main excitement here is Peter Zijlstra's lockless rbtree optimization
to speed module address lookup. He found some abusers of the module
lock doing that too.

A little bit of parameter work here too; including Dan Streetman's
breaking up the big param mutex so writing a parameter can load
another module (yeah, really). Unfortunately that broke the usual
suspects, !CONFIG_MODULES and !CONFIG_SYSFS, so those fixes were
appended too"

* tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (26 commits)
modules: only use mod->param_lock if CONFIG_MODULES
param: fix module param locks when !CONFIG_SYSFS.
rcu: merge fix for Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
module: add per-module param_lock
module: make perm const
params: suppress unused variable error, warn once just in case code changes.
modules: clarify CONFIG_MODULE_COMPRESS help, suggest 'N'.
kernel/module.c: avoid ifdefs for sig_enforce declaration
kernel/workqueue.c: remove ifdefs over wq_power_efficient
kernel/params.c: export param_ops_bool_enable_only
kernel/params.c: generalize bool_enable_only
kernel/module.c: use generic module param operaters for sig_enforce
kernel/params: constify struct kernel_param_ops uses
sysfs: tightened sysfs permission checks
module: Rework module_addr_{min,max}
module: Use __module_address() for module_address_lookup()
module: Make the mod_tree stuff conditional on PERF_EVENTS || TRACING
module: Optimize __module_address() using a latched RB-tree
rbtree: Implement generic latch_tree
seqlock: Introduce raw_read_seqcount_latch()
...

arch/s390/kernel/perf_cpum_sf.c

···
 }
 
 #define param_check_sfb_size(name, p) __param_check(name, p, void)
-static struct kernel_param_ops param_ops_sfb_size = {
+static const struct kernel_param_ops param_ops_sfb_size = {
 	.set = param_set_sfb_size,
 	.get = param_get_sfb_size,
 };

arch/um/drivers/hostaudio_kern.c

···
 	int ret;
 
 #ifdef DEBUG
-	kparam_block_sysfs_write(dsp);
+	kernel_param_lock(THIS_MODULE);
 	printk(KERN_DEBUG "hostaudio: open called (host: %s)\n", dsp);
-	kparam_unblock_sysfs_write(dsp);
+	kernel_param_unlock(THIS_MODULE);
 #endif
 
 	state = kmalloc(sizeof(struct hostaudio_state), GFP_KERNEL);
···
 	if (file->f_mode & FMODE_WRITE)
 		w = 1;
 
-	kparam_block_sysfs_write(dsp);
+	kernel_param_lock(THIS_MODULE);
 	mutex_lock(&hostaudio_mutex);
 	ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
 	mutex_unlock(&hostaudio_mutex);
-	kparam_unblock_sysfs_write(dsp);
+	kernel_param_unlock(THIS_MODULE);
 
 	if (ret < 0) {
 		kfree(state);
···
 	if (file->f_mode & FMODE_WRITE)
 		w = 1;
 
-	kparam_block_sysfs_write(mixer);
+	kernel_param_lock(THIS_MODULE);
 	mutex_lock(&hostaudio_mutex);
 	ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
 	mutex_unlock(&hostaudio_mutex);
-	kparam_unblock_sysfs_write(mixer);
+	kernel_param_unlock(THIS_MODULE);
 
 	if (ret < 0) {
-		kparam_block_sysfs_write(dsp);
+		kernel_param_lock(THIS_MODULE);
 		printk(KERN_ERR "hostaudio_open_mixdev failed to open '%s', "
 		       "err = %d\n", dsp, -ret);
-		kparam_unblock_sysfs_write(dsp);
+		kernel_param_unlock(THIS_MODULE);
 		kfree(state);
 		return ret;
 	}
···
 
 static int __init hostaudio_init_module(void)
 {
-	__kernel_param_lock();
+	kernel_param_lock(THIS_MODULE);
 	printk(KERN_INFO "UML Audio Relay (host dsp = %s, host mixer = %s)\n",
 	       dsp, mixer);
-	__kernel_param_unlock();
+	kernel_param_unlock(THIS_MODULE);
 
 	module_data.dev_audio = register_sound_dsp(&hostaudio_fops, -1);
 	if (module_data.dev_audio < 0) {

arch/x86/kvm/mmu_audit.c

···
 	return 0;
 }
 
-static struct kernel_param_ops audit_param_ops = {
+static const struct kernel_param_ops audit_param_ops = {
 	.set = mmu_audit_set,
 	.get = param_get_bool,
 };

arch/x86/platform/uv/uv_nmi.c

···
 	return 0;
 }
 
-static struct kernel_param_ops param_ops_local64 = {
+static const struct kernel_param_ops param_ops_local64 = {
 	.get = param_get_local64,
 	.set = param_set_local64,
 };

drivers/block/null_blk.c

···
 	return null_param_store_val(str, &queue_mode, NULL_Q_BIO, NULL_Q_MQ);
 }
 
-static struct kernel_param_ops null_queue_mode_param_ops = {
+static const struct kernel_param_ops null_queue_mode_param_ops = {
 	.set	= null_set_queue_mode,
 	.get	= param_get_int,
 };
···
 					NULL_IRQ_TIMER);
 }
 
-static struct kernel_param_ops null_irqmode_param_ops = {
+static const struct kernel_param_ops null_irqmode_param_ops = {
 	.set	= null_set_irqmode,
 	.get	= param_get_int,
 };

drivers/char/ipmi/ipmi_watchdog.c

···
 	return rv;
 }
 
-static struct kernel_param_ops param_ops_timeout = {
+static const struct kernel_param_ops param_ops_timeout = {
 	.set = set_param_timeout,
 	.get = param_get_int,
 };
···
 	return 0;
 }
 
-static struct kernel_param_ops param_ops_wdog_ifnum = {
+static const struct kernel_param_ops param_ops_wdog_ifnum = {
 	.set = set_param_wdog_ifnum,
 	.get = param_get_int,
 };
 
 #define param_check_wdog_ifnum param_check_int
 
-static struct kernel_param_ops param_ops_str = {
+static const struct kernel_param_ops param_ops_str = {
 	.set = set_param_str,
 	.get = get_param_str,
 };

drivers/dma/dmatest.c

···
 
 static int dmatest_run_set(const char *val, const struct kernel_param *kp);
 static int dmatest_run_get(char *val, const struct kernel_param *kp);
-static struct kernel_param_ops run_ops = {
+static const struct kernel_param_ops run_ops = {
 	.set = dmatest_run_set,
 	.get = dmatest_run_get,
 };
···
 	return param_get_bool(val, kp);
 }
 
-static struct kernel_param_ops wait_ops = {
+static const struct kernel_param_ops wait_ops = {
 	.get = dmatest_wait_get,
 	.set = param_set_bool,
 };

drivers/ide/ide.c

···
 	return 0;
 }
 
-static struct kernel_param_ops param_ops_ide_dev_mask = {
+static const struct kernel_param_ops param_ops_ide_dev_mask = {
 	.set = ide_set_dev_param_mask
 };
 

drivers/infiniband/ulp/srp/ib_srp.c

···
 MODULE_PARM_DESC(register_always,
 		 "Use memory registration even for contiguous memory regions");
 
-static struct kernel_param_ops srp_tmo_ops;
+static const struct kernel_param_ops srp_tmo_ops;
 
 static int srp_reconnect_delay = 10;
 module_param_cb(reconnect_delay, &srp_tmo_ops, &srp_reconnect_delay,
···
 	return res;
 }
 
-static struct kernel_param_ops srp_tmo_ops = {
+static const struct kernel_param_ops srp_tmo_ops = {
 	.get = srp_tmo_get,
 	.set = srp_tmo_set,
 };

drivers/input/misc/ati_remote2.c

···
 
 static unsigned int channel_mask = ATI_REMOTE2_MAX_CHANNEL_MASK;
 #define param_check_channel_mask(name, p) __param_check(name, p, unsigned int)
-static struct kernel_param_ops param_ops_channel_mask = {
+static const struct kernel_param_ops param_ops_channel_mask = {
 	.set = ati_remote2_set_channel_mask,
 	.get = ati_remote2_get_channel_mask,
 };
···
 
 static unsigned int mode_mask = ATI_REMOTE2_MAX_MODE_MASK;
 #define param_check_mode_mask(name, p) __param_check(name, p, unsigned int)
-static struct kernel_param_ops param_ops_mode_mask = {
+static const struct kernel_param_ops param_ops_mode_mask = {
 	.set = ati_remote2_set_mode_mask,
 	.get = ati_remote2_get_mode_mask,
 };

drivers/input/mouse/psmouse-base.c

···
 static unsigned int psmouse_max_proto = PSMOUSE_AUTO;
 static int psmouse_set_maxproto(const char *val, const struct kernel_param *);
 static int psmouse_get_maxproto(char *buffer, const struct kernel_param *kp);
-static struct kernel_param_ops param_ops_proto_abbrev = {
+static const struct kernel_param_ops param_ops_proto_abbrev = {
 	.set = psmouse_set_maxproto,
 	.get = psmouse_get_maxproto,
 };

drivers/misc/lis3lv02d/lis3lv02d.c

···
 	return ret;
 }
 
-static struct kernel_param_ops param_ops_axis = {
+static const struct kernel_param_ops param_ops_axis = {
 	.set = param_set_axis,
 	.get = param_get_int,
 };

drivers/mtd/ubi/block.c

···
 	return 0;
 }
 
-static struct kernel_param_ops ubiblock_param_ops = {
+static const struct kernel_param_ops ubiblock_param_ops = {
 	.set    = ubiblock_set_param,
 };
 module_param_cb(block, &ubiblock_param_ops, NULL, 0);

drivers/net/ethernet/myricom/myri10ge/myri10ge.c

···
 MODULE_FIRMWARE("myri10ge_rss_ethp_z8e.dat");
 MODULE_FIRMWARE("myri10ge_rss_eth_z8e.dat");
 
-/* Careful: must be accessed under kparam_block_sysfs_write */
+/* Careful: must be accessed under kernel_param_lock() */
 static char *myri10ge_fw_name = NULL;
 module_param(myri10ge_fw_name, charp, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(myri10ge_fw_name, "Firmware image name");
···
 		}
 	}
 
-	kparam_block_sysfs_write(myri10ge_fw_name);
+	kernel_param_lock(THIS_MODULE);
 	if (myri10ge_fw_name != NULL) {
 		char *fw_name = kstrdup(myri10ge_fw_name, GFP_KERNEL);
 		if (fw_name) {
···
 			set_fw_name(mgp, fw_name, true);
 		}
 	}
-	kparam_unblock_sysfs_write(myri10ge_fw_name);
+	kernel_param_unlock(THIS_MODULE);
 
 	if (mgp->board_number < MYRI10GE_MAX_BOARDS &&
 	    myri10ge_fw_names[mgp->board_number] != NULL &&

drivers/net/wireless/ath/wil6210/main.c

···
 	return ret;
 }
 
-static struct kernel_param_ops mtu_max_ops = {
+static const struct kernel_param_ops mtu_max_ops = {
 	.set = mtu_max_set,
 	.get = param_get_uint,
 };
···
 	return 0;
 }
 
-static struct kernel_param_ops ring_order_ops = {
+static const struct kernel_param_ops ring_order_ops = {
 	.set = ring_order_set,
 	.get = param_get_uint,
 };

drivers/net/wireless/libertas_tf/if_usb.c

···
 
 	lbtf_deb_enter(LBTF_DEB_USB);
 
-	kparam_block_sysfs_write(fw_name);
+	kernel_param_lock(THIS_MODULE);
 	ret = request_firmware(&cardp->fw, lbtf_fw_name, &cardp->udev->dev);
 	if (ret < 0) {
 		pr_err("request_firmware() failed with %#x\n", ret);
 		pr_err("firmware %s not found\n", lbtf_fw_name);
-		kparam_unblock_sysfs_write(fw_name);
+		kernel_param_unlock(THIS_MODULE);
 		goto done;
 	}
-	kparam_unblock_sysfs_write(fw_name);
+	kernel_param_unlock(THIS_MODULE);
 
 	if (check_fwfile_format(cardp->fw->data, cardp->fw->size))
 		goto release_fw;

drivers/power/test_power.c

···
 
 #define param_get_battery_voltage param_get_int
 
-static struct kernel_param_ops param_ops_ac_online = {
+static const struct kernel_param_ops param_ops_ac_online = {
 	.set = param_set_ac_online,
 	.get = param_get_ac_online,
 };
 
-static struct kernel_param_ops param_ops_usb_online = {
+static const struct kernel_param_ops param_ops_usb_online = {
 	.set = param_set_usb_online,
 	.get = param_get_usb_online,
 };
 
-static struct kernel_param_ops param_ops_battery_status = {
+static const struct kernel_param_ops param_ops_battery_status = {
 	.set = param_set_battery_status,
 	.get = param_get_battery_status,
 };
 
-static struct kernel_param_ops param_ops_battery_present = {
+static const struct kernel_param_ops param_ops_battery_present = {
 	.set = param_set_battery_present,
 	.get = param_get_battery_present,
 };
 
-static struct kernel_param_ops param_ops_battery_technology = {
+static const struct kernel_param_ops param_ops_battery_technology = {
 	.set = param_set_battery_technology,
 	.get = param_get_battery_technology,
 };
 
-static struct kernel_param_ops param_ops_battery_health = {
+static const struct kernel_param_ops param_ops_battery_health = {
 	.set = param_set_battery_health,
 	.get = param_get_battery_health,
 };
 
-static struct kernel_param_ops param_ops_battery_capacity = {
+static const struct kernel_param_ops param_ops_battery_capacity = {
 	.set = param_set_battery_capacity,
 	.get = param_get_battery_capacity,
 };
 
-static struct kernel_param_ops param_ops_battery_voltage = {
+static const struct kernel_param_ops param_ops_battery_voltage = {
 	.set = param_set_battery_voltage,
 	.get = param_get_battery_voltage,
 };

drivers/thermal/intel_powerclamp.c

···
 	return ret;
 }
 
-static struct kernel_param_ops duration_ops = {
+static const struct kernel_param_ops duration_ops = {
 	.set = duration_set,
 	.get = param_get_int,
 };
···
 	return ret;
 }
 
-static struct kernel_param_ops window_size_ops = {
+static const struct kernel_param_ops window_size_ops = {
 	.set = window_size_set,
 	.get = param_get_int,
 };

drivers/tty/hvc/hvc_iucv.c

···
 
 #define param_check_vmidfilter(name, p) __param_check(name, p, void)
 
-static struct kernel_param_ops param_ops_vmidfilter = {
+static const struct kernel_param_ops param_ops_vmidfilter = {
 	.set = param_set_vmidfilter,
 	.get = param_get_vmidfilter,
 };

drivers/tty/sysrq.c

···
 	return 0;
 }
 
-static struct kernel_param_ops param_ops_sysrq_reset_seq = {
+static const struct kernel_param_ops param_ops_sysrq_reset_seq = {
 	.get	= param_get_ushort,
 	.set	= sysrq_reset_seq_param_set,
 };

drivers/usb/atm/ueagle-atm.c

···
 	char file_arr[] = "CMVxy.bin";
 	char *file;
 
-	kparam_block_sysfs_write(cmv_file);
+	kernel_param_lock(THIS_MODULE);
 	/* set proper name corresponding modem version and line type */
 	if (cmv_file[sc->modem_index] == NULL) {
 		if (UEA_CHIP_VERSION(sc) == ADI930)
···
 	strlcat(cmv_name, file, UEA_FW_NAME_MAX);
 	if (ver == 2)
 		strlcat(cmv_name, ".v2", UEA_FW_NAME_MAX);
-	kparam_unblock_sysfs_write(cmv_file);
+	kernel_param_unlock(THIS_MODULE);
 }
 
 static int request_cmvs_old(struct uea_softc *sc,

drivers/video/fbdev/uvesafb.c

···
 
 	return 0;
 }
-static struct kernel_param_ops param_ops_scroll = {
+static const struct kernel_param_ops param_ops_scroll = {
 	.set = param_set_scroll,
 };
 #define param_check_scroll(name, p) __param_check(name, p, void)

drivers/video/fbdev/vt8623fb.c

···
 
 	/* Prepare startup mode */
 
-	kparam_block_sysfs_write(mode_option);
+	kernel_param_lock(THIS_MODULE);
 	rc = fb_find_mode(&(info->var), info, mode_option, NULL, 0, NULL, 8);
-	kparam_unblock_sysfs_write(mode_option);
+	kernel_param_unlock(THIS_MODULE);
 	if (! ((rc == 1) || (rc == 2))) {
 		rc = -EINVAL;
 		dev_err(info->device, "mode %s not found\n", mode_option);

drivers/virtio/virtio_mmio.c

···
 	return strlen(buffer) + 1;
 }
 
-static struct kernel_param_ops vm_cmdline_param_ops = {
+static const struct kernel_param_ops vm_cmdline_param_ops = {
 	.set = vm_cmdline_set,
 	.get = vm_cmdline_get,
 };

fs/nfs/super.c

···
 	*((unsigned int *)kp->arg) = num;
 	return 0;
 }
-static struct kernel_param_ops param_ops_portnr = {
+static const struct kernel_param_ops param_ops_portnr = {
 	.set = param_set_portnr,
 	.get = param_get_uint,
 };

include/linux/compiler.h

···
 	(volatile typeof(x) *)&(x); })
 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
 
+/**
+ * lockless_dereference() - safely load a pointer for later dereference
+ * @p: The pointer to load
+ *
+ * Similar to rcu_dereference(), but for situations where the pointed-to
+ * object's lifetime is managed by something other than RCU.  That
+ * "something other" might be reference counting or simple immortality.
+ */
+#define lockless_dereference(p) \
+({ \
+	typeof(p) _________p1 = READ_ONCE(p); \
+	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
+	(_________p1); \
+})
+
 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */
 #ifdef CONFIG_KPROBES
 # define __kprobes	__attribute__((__section__(".kprobes.text")))

include/linux/kernel.h

···
 #endif
 
 /* Permissions on a sysfs file: you didn't miss the 0 prefix did you? */
-#define VERIFY_OCTAL_PERMISSIONS(perms)					\
-	(BUILD_BUG_ON_ZERO((perms) < 0) +				\
-	 BUILD_BUG_ON_ZERO((perms) > 0777) +				\
-	 /* User perms >= group perms >= other perms */			\
-	 BUILD_BUG_ON_ZERO(((perms) >> 6) < (((perms) >> 3) & 7)) +	\
-	 BUILD_BUG_ON_ZERO((((perms) >> 3) & 7) < ((perms) & 7)) +	\
-	 /* Other writable?  Generally considered a bad idea. */	\
-	 BUILD_BUG_ON_ZERO((perms) & 2) +				\
+#define VERIFY_OCTAL_PERMISSIONS(perms)						\
+	(BUILD_BUG_ON_ZERO((perms) < 0) +					\
+	 BUILD_BUG_ON_ZERO((perms) > 0777) +					\
+	 /* USER_READABLE >= GROUP_READABLE >= OTHER_READABLE */		\
+	 BUILD_BUG_ON_ZERO((((perms) >> 6) & 4) < (((perms) >> 3) & 4)) +	\
+	 BUILD_BUG_ON_ZERO((((perms) >> 3) & 4) < ((perms) & 4)) +		\
+	 /* USER_WRITABLE >= GROUP_WRITABLE */					\
+	 BUILD_BUG_ON_ZERO((((perms) >> 6) & 2) < (((perms) >> 3) & 2)) +	\
+	 /* OTHER_WRITABLE?  Generally considered a bad idea. */		\
+	 BUILD_BUG_ON_ZERO((perms) & 2) +					\
 	 (perms))
 #endif

include/linux/module.h

···
 #include <linux/moduleparam.h>
 #include <linux/jump_label.h>
 #include <linux/export.h>
+#include <linux/rbtree_latch.h>
 
 #include <linux/percpu.h>
 #include <asm/module.h>
···
 	MODULE_STATE_UNFORMED,	/* Still setting it up. */
 };
 
+struct module;
+
+struct mod_tree_node {
+	struct module *mod;
+	struct latch_tree_node node;
+};
+
 struct module {
 	enum module_state state;
 
···
 	unsigned int num_syms;
 
 	/* Kernel parameters. */
+#ifdef CONFIG_SYSFS
+	struct mutex param_lock;
+#endif
 	struct kernel_param *kp;
 	unsigned int num_kp;
 
···
 	/* Startup function. */
 	int (*init)(void);
 
-	/* If this is non-NULL, vfree after init() returns */
-	void *module_init;
+	/*
+	 * If this is non-NULL, vfree() after init() returns.
+	 *
+	 * Cacheline align here, such that:
+	 *   module_init, module_core, init_size, core_size,
+	 *   init_text_size, core_text_size and mtn_core::{mod,node[0]}
+	 * are on the same cacheline.
+	 */
+	void *module_init	____cacheline_aligned;
 
 	/* Here is the actual code + data, vfree'd on unload. */
 	void *module_core;
···
 
 	/* The size of the executable code in each section.  */
 	unsigned int init_text_size, core_text_size;
+
+#ifdef CONFIG_MODULES_TREE_LOOKUP
+	/*
+	 * We want mtn_core::{mod,node[0]} to be in the same cacheline as the
+	 * above entries such that a regular lookup will only touch one
+	 * cacheline.
+	 */
+	struct mod_tree_node	mtn_core;
+	struct mod_tree_node	mtn_init;
+#endif
 
 	/* Size of RO sections of the module (text+rodata) */
 	unsigned int init_ro_size, core_ro_size;
···
 	ctor_fn_t *ctors;
 	unsigned int num_ctors;
 #endif
-};
+} ____cacheline_aligned;
 #ifndef MODULE_ARCH_INIT
 #define MODULE_ARCH_INIT {}
 #endif
···
 	bool unused;
 };
 
-/* Search for an exported symbol by name. */
+/*
+ * Search for an exported symbol by name.
+ *
+ * Must be called with module_mutex held or preemption disabled.
+ */
 const struct kernel_symbol *find_symbol(const char *name,
 					struct module **owner,
 					const unsigned long **crc,
 					bool gplok,
 					bool warn);
 
-/* Walk the exported symbol table */
+/*
+ * Walk the exported symbol table
+ *
+ * Must be called with module_mutex held or preemption disabled.
+ */
 bool each_symbol_section(bool (*fn)(const struct symsearch *arr,
 				    struct module *owner,
 				    void *data), void *data);

include/linux/moduleparam.h

···
 
 struct kernel_param {
 	const char *name;
+	struct module *mod;
 	const struct kernel_param_ops *ops;
-	u16 perm;
+	const u16 perm;
 	s8 level;
 	u8 flags;
 	union {
···
  *
  * @perm is 0 if the the variable is not to appear in sysfs, or 0444
  * for world-readable, 0644 for root-writable, etc.  Note that if it
- * is writable, you may need to use kparam_block_sysfs_write() around
+ * is writable, you may need to use kernel_param_lock() around
  * accesses (esp. charp, which can be kfreed when it changes).
  *
  * The @type is simply pasted to refer to a param_ops_##type and a
···
    parameters. */
 #define __module_param_call(prefix, name, ops, arg, perm, level, flags)	\
 	/* Default value instead of permissions? */			\
-	static const char __param_str_##name[] = prefix #name; \
+	static const char __param_str_##name[] = prefix #name;		\
 	static struct kernel_param __moduleparam_const __param_##name	\
 	__used								\
     __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
-	= { __param_str_##name, ops, VERIFY_OCTAL_PERMISSIONS(perm),	\
-	    level, flags, { arg } }
+	= { __param_str_##name, THIS_MODULE, ops,			\
+	    VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } }
 
 /* Obsolete - use module_param_cb() */
 #define module_param_call(name, set, get, arg, perm)			\
-	static struct kernel_param_ops __param_ops_##name =		\
+	static const struct kernel_param_ops __param_ops_##name =		\
 		{ .flags = 0, (void *)set, (void *)get };		\
 	__module_param_call(MODULE_PARAM_PREFIX,			\
 			    name, &__param_ops_##name, arg,		\
···
 	return 0;
 }
 
-/**
- * kparam_block_sysfs_write - make sure a parameter isn't written via sysfs.
- * @name: the name of the parameter
- *
- * There's no point blocking write on a paramter that isn't writable via sysfs!
- */
-#define kparam_block_sysfs_write(name)			\
-	do {						\
-		BUG_ON(!(__param_##name.perm & 0222));	\
-		__kernel_param_lock();			\
-	} while (0)
-
-/**
- * kparam_unblock_sysfs_write - allows sysfs to write to a parameter again.
- * @name: the name of the parameter
- */
-#define kparam_unblock_sysfs_write(name)		\
-	do {						\
-		BUG_ON(!(__param_##name.perm & 0222));	\
-		__kernel_param_unlock();		\
-	} while (0)
-
-/**
- * kparam_block_sysfs_read - make sure a parameter isn't read via sysfs.
- * @name: the name of the parameter
- *
- * This also blocks sysfs writes.
- */
-#define kparam_block_sysfs_read(name)			\
-	do {						\
-		BUG_ON(!(__param_##name.perm & 0444));	\
-		__kernel_param_lock();			\
-	} while (0)
-
-/**
- * kparam_unblock_sysfs_read - allows sysfs to read a parameter again.
- * @name: the name of the parameter
- */
-#define kparam_unblock_sysfs_read(name)			\
-	do {						\
-		BUG_ON(!(__param_##name.perm & 0444));	\
-		__kernel_param_unlock();		\
-	} while (0)
-
 #ifdef CONFIG_SYSFS
-extern void __kernel_param_lock(void);
-extern void __kernel_param_unlock(void);
+extern void kernel_param_lock(struct module *mod);
+extern void kernel_param_unlock(struct module *mod);
 #else
-static inline void __kernel_param_lock(void)
+static inline void kernel_param_lock(struct module *mod)
 {
 }
-static inline void __kernel_param_unlock(void)
+static inline void kernel_param_unlock(struct module *mod)
 {
 }
 #endif
···
 #define __param_check(name, p, type) \
 	static inline type __always_unused *__check_##name(void) { return(p); }
 
-extern struct kernel_param_ops param_ops_byte;
+extern const struct kernel_param_ops param_ops_byte;
 extern int param_set_byte(const char *val, const struct kernel_param *kp);
 extern int param_get_byte(char *buffer, const struct kernel_param *kp);
 #define param_check_byte(name, p) __param_check(name, p, unsigned char)
 
-extern struct kernel_param_ops param_ops_short;
+extern const struct kernel_param_ops param_ops_short;
 extern int param_set_short(const char *val, const struct kernel_param *kp);
 extern int param_get_short(char *buffer, const struct kernel_param *kp);
 #define param_check_short(name, p) __param_check(name, p, short)
 
-extern struct kernel_param_ops param_ops_ushort;
+extern const struct kernel_param_ops param_ops_ushort;
 extern int param_set_ushort(const char *val, const struct kernel_param *kp);
 extern int param_get_ushort(char *buffer, const struct kernel_param *kp);
 #define param_check_ushort(name, p) __param_check(name, p, unsigned short)
 
-extern struct kernel_param_ops param_ops_int;
+extern const struct kernel_param_ops param_ops_int;
 extern int param_set_int(const char *val, const struct kernel_param *kp);
 extern int param_get_int(char *buffer, const struct kernel_param *kp);
 #define param_check_int(name, p) __param_check(name, p, int)
 
-extern struct kernel_param_ops param_ops_uint;
+extern const struct kernel_param_ops param_ops_uint;
 extern int param_set_uint(const char *val, const struct kernel_param *kp);
 extern int param_get_uint(char *buffer, const struct kernel_param *kp);
 #define param_check_uint(name, p) __param_check(name, p, unsigned int)
 
-extern struct kernel_param_ops param_ops_long;
+extern const struct kernel_param_ops param_ops_long;
 extern int param_set_long(const char *val, const struct kernel_param *kp);
 extern int param_get_long(char *buffer, const struct kernel_param *kp);
 #define param_check_long(name, p) __param_check(name, p, long)
 
-extern struct kernel_param_ops param_ops_ulong;
+extern const struct kernel_param_ops param_ops_ulong;
 extern int param_set_ulong(const char *val, const struct kernel_param *kp);
 extern int param_get_ulong(char *buffer, const struct kernel_param *kp);
 #define param_check_ulong(name, p) __param_check(name, p, unsigned long)
 
-extern struct kernel_param_ops param_ops_ullong;
+extern const struct kernel_param_ops param_ops_ullong;
 extern int param_set_ullong(const char *val, const struct kernel_param *kp);
 extern int param_get_ullong(char *buffer, const struct kernel_param *kp);
 #define param_check_ullong(name, p) __param_check(name, p, unsigned long long)
 
-extern struct kernel_param_ops param_ops_charp;
+extern const struct kernel_param_ops param_ops_charp;
 extern int param_set_charp(const char *val, const struct kernel_param *kp);
 extern int param_get_charp(char *buffer, const struct kernel_param *kp);
 #define param_check_charp(name, p) __param_check(name, p, char *)
 
 /* We used to allow int as well as bool.  We're taking that away! */
-extern struct kernel_param_ops param_ops_bool;
+extern const struct kernel_param_ops param_ops_bool;
 extern int param_set_bool(const char *val, const struct kernel_param *kp);
 extern int param_get_bool(char *buffer, const struct kernel_param *kp);
 #define param_check_bool(name, p) __param_check(name, p, bool)
 
-extern struct kernel_param_ops param_ops_invbool;
+extern const struct kernel_param_ops param_ops_bool_enable_only;
+extern int param_set_bool_enable_only(const char *val,
+				      const struct kernel_param *kp);
+/* getter is the same as for the regular bool */
+#define param_check_bool_enable_only param_check_bool
+
+extern const struct kernel_param_ops param_ops_invbool;
 extern int param_set_invbool(const char *val, const struct kernel_param *kp);
 extern int param_get_invbool(char *buffer, const struct kernel_param *kp);
 #define param_check_invbool(name, p) __param_check(name, p, bool)
 
 /* An int, which can only be set like a bool (though it shows as an int). */
-extern struct kernel_param_ops param_ops_bint;
+extern const struct kernel_param_ops param_ops_bint;
 extern int param_set_bint(const char *val, const struct kernel_param *kp);
 #define param_get_bint param_get_int
 #define param_check_bint param_check_int
···
 			    perm, -1, 0);				\
 	__MODULE_PARM_TYPE(name, "array of " #type)
 
-extern struct kernel_param_ops param_array_ops;
+extern const struct kernel_param_ops param_array_ops;
 
-extern struct kernel_param_ops param_ops_string;
+extern const struct kernel_param_ops param_ops_string;
 extern int param_set_copystring(const char *val, const struct kernel_param *);
 extern int param_get_string(char *buffer, const struct kernel_param *kp);
 

include/linux/rbtree.h

···
 
 #include <linux/kernel.h>
 #include <linux/stddef.h>
+#include <linux/rcupdate.h>
 
 struct rb_node {
 	unsigned long  __rb_parent_color;
···
 extern struct rb_node *rb_next_postorder(const struct rb_node *);
 
 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
-extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
 			    struct rb_root *root);
 
-static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
-				struct rb_node ** rb_link)
+static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
+				struct rb_node **rb_link)
 {
 	node->__rb_parent_color = (unsigned long)parent;
 	node->rb_left = node->rb_right = NULL;
 
 	*rb_link = node;
+}
+
+static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
+				    struct rb_node **rb_link)
+{
+	node->__rb_parent_color = (unsigned long)parent;
+	node->rb_left = node->rb_right = NULL;
+
+	rcu_assign_pointer(*rb_link, node);
 }
 
 #define rb_entry_safe(ptr, type, member) \

include/linux/rbtree_augmented.h

···
 {
 	if (parent) {
 		if (parent->rb_left == old)
-			parent->rb_left = new;
+			WRITE_ONCE(parent->rb_left, new);
 		else
-			parent->rb_right = new;
+			WRITE_ONCE(parent->rb_right, new);
 	} else
-		root->rb_node = new;
+		WRITE_ONCE(root->rb_node, new);
 }
 
 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
···
 __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 		     const struct rb_augment_callbacks *augment)
 {
-	struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+	struct rb_node *child = node->rb_right;
+	struct rb_node *tmp = node->rb_left;
 	struct rb_node *parent, *rebalance;
 	unsigned long pc;
 
···
 		tmp = parent;
 	} else {
 		struct rb_node *successor = child, *child2;
+
 		tmp = child->rb_left;
 		if (!tmp) {
 			/*
···
 			 */
 			parent = successor;
 			child2 = successor->rb_right;
+
 			augment->copy(node, successor);
 		} else {
 			/*
···
 				successor = tmp;
 				tmp = tmp->rb_left;
 			} while (tmp);
-			parent->rb_left = child2 = successor->rb_right;
-			successor->rb_right = child;
+			child2 = successor->rb_right;
+			WRITE_ONCE(parent->rb_left, child2);
+			WRITE_ONCE(successor->rb_right, child);
 			rb_set_parent(child, successor);
+
 			augment->copy(node, successor);
 			augment->propagate(parent, successor);
 		}
 
-		successor->rb_left = tmp = node->rb_left;
+		tmp = node->rb_left;
+		WRITE_ONCE(successor->rb_left, tmp);
 		rb_set_parent(tmp, successor);
 
 		pc = node->__rb_parent_color;
 		tmp = __rb_parent(pc);
 		__rb_change_child(node, successor, tmp, root);
+
 		if (child2) {
 			successor->__rb_parent_color = pc;
 			rb_set_parent_color(child2, parent, RB_BLACK);

include/linux/rbtree_latch.h

···
+/*
+ * Latched RB-trees
+ *
+ * Copyright (C) 2015 Intel Corp., Peter Zijlstra <[e-mail]>
+ *
+ * Since RB-trees have non-atomic modifications they're not immediately suited
+ * for RCU/lockless queries. Even though we made RB-tree lookups non-fatal for
+ * lockless lookups; we cannot guarantee they return a correct result.
+ *
+ * The simplest solution is a seqlock + RB-tree, this will allow lockless
+ * lookups; but has the constraint (inherent to the seqlock) that read sides
+ * cannot nest in write sides.
+ *
+ * If we need to allow unconditional lookups (say as required for NMI context
+ * usage) we need a more complex setup; this data structure provides this by
+ * employing the latch technique -- see @raw_write_seqcount_latch -- to
+ * implement a latched RB-tree which does allow for unconditional lookups by
+ * virtue of always having (at least) one stable copy of the tree.
+ *
+ * However, while we have the guarantee that there is at all times one stable
+ * copy, this does not guarantee an iteration will not observe modifications.
+ * What might have been a stable copy at the start of the iteration, need not
+ * remain so for the duration of the iteration.
+ *
+ * Therefore, this does require a lockless RB-tree iteration to be non-fatal;
+ * see the comment in lib/rbtree.c. Note however that we only require the first
+ * condition -- not seeing partial stores -- because the latch thing isolates
+ * us from loops. If we were to interrupt a modification the lookup would be
+ * pointed at the stable tree and complete while the modification was halted.
+ */
+
+#ifndef RB_TREE_LATCH_H
+#define RB_TREE_LATCH_H
+
+#include <linux/rbtree.h>
+#include <linux/seqlock.h>
+
+struct latch_tree_node {
+	struct rb_node node[2];
+};
+
+struct latch_tree_root {
+	seqcount_t	seq;
+	struct rb_root	tree[2];
+};
+
+/**
+ * latch_tree_ops - operators to define the tree order
+ * @less: used for insertion; provides the (partial) order between two elements.
+ * @comp: used for lookups; provides the order between the search key and an element.
+ *
+ * The operators are related like:
+ *
+ *	comp(a->key,b) < 0  := less(a,b)
+ *	comp(a->key,b) > 0  := less(b,a)
+ *	comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
+ *
+ * If these operators define a partial order on the elements we make no
+ * guarantee on which of the elements matching the key is found. See
+ * latch_tree_find().
+ */
+struct latch_tree_ops {
+	bool (*less)(struct latch_tree_node *a, struct latch_tree_node *b);
+	int  (*comp)(void *key,                 struct latch_tree_node *b);
+};
+
+static __always_inline struct latch_tree_node *
+__lt_from_rb(struct rb_node *node, int idx)
+{
+	return container_of(node, struct latch_tree_node, node[idx]);
+}
+
+static __always_inline void
+__lt_insert(struct latch_tree_node *ltn, struct latch_tree_root *ltr, int idx,
+	    bool (*less)(struct latch_tree_node *a, struct latch_tree_node *b))
+{
+	struct rb_root *root = &ltr->tree[idx];
+	struct rb_node **link = &root->rb_node;
+	struct rb_node *node = &ltn->node[idx];
+	struct rb_node *parent = NULL;
+	struct latch_tree_node *ltp;
+
+	while (*link) {
+		parent = *link;
+		ltp = __lt_from_rb(parent, idx);
+
+		if (less(ltn, ltp))
+			link = &parent->rb_left;
+		else
+			link = &parent->rb_right;
+	}
+
+	rb_link_node_rcu(node, parent, link);
+	rb_insert_color(node, root);
+}
+
+static __always_inline void
+__lt_erase(struct latch_tree_node *ltn, struct latch_tree_root *ltr, int idx)
+{
+	rb_erase(&ltn->node[idx], &ltr->tree[idx]);
+}
+
+static __always_inline struct latch_tree_node *
+__lt_find(void *key, struct latch_tree_root *ltr, int idx,
+	  int (*comp)(void *key, struct latch_tree_node *node))
+{
+	struct rb_node *node = rcu_dereference_raw(ltr->tree[idx].rb_node);
+	struct latch_tree_node *ltn;
+	int c;
+
+	while (node) {
+		ltn = __lt_from_rb(node, idx);
+		c = comp(key, ltn);
+
+		if (c < 0)
+			node = rcu_dereference_raw(node->rb_left);
+		else if (c > 0)
+			node = rcu_dereference_raw(node->rb_right);
+		else
+			return ltn;
+	}
+
+	return NULL;
+}
+
+/**
+ * latch_tree_insert() - insert @node into the trees @root
+ * @node: nodes to insert
+ * @root: trees to insert @node into
+ * @ops: operators defining the node order
+ *
+ * It inserts @node into @root in an ordered fashion such that we can always
+ * observe one complete tree. See the comment for raw_write_seqcount_latch().
+ *
+ * The inserts use rcu_assign_pointer() to publish the element such that the
+ * tree structure is stored before we can observe the new @node.
+ *
+ * All modifications (latch_tree_insert, latch_tree_remove) are assumed to be
+ * serialized.
+ */
+static __always_inline void
+latch_tree_insert(struct latch_tree_node *node,
+		  struct latch_tree_root *root,
+		  const struct latch_tree_ops *ops)
+{
+	raw_write_seqcount_latch(&root->seq);
+	__lt_insert(node, root, 0, ops->less);
+	raw_write_seqcount_latch(&root->seq);
+	__lt_insert(node, root, 1, ops->less);
+}
+
+/**
+ * latch_tree_erase() - removes @node from the trees @root
+ * @node: nodes to remote
+ * @root: trees to remove @node from
+ * @ops: operators defining the node order
+ *
+ * Removes @node from the trees @root in an ordered fashion such that we can
+ * always observe one complete tree. See the comment for
+ * raw_write_seqcount_latch().
+ *
+ * It is assumed that @node will observe one RCU quiescent state before being
+ * reused of freed.
+ *
+ * All modifications (latch_tree_insert, latch_tree_remove) are assumed to be
+ * serialized.
+ */
+static __always_inline void
+latch_tree_erase(struct latch_tree_node *node,
+		 struct latch_tree_root *root,
+		 const struct latch_tree_ops *ops)
+{
+	raw_write_seqcount_latch(&root->seq);
+	__lt_erase(node, root, 0);
+	raw_write_seqcount_latch(&root->seq);
+	__lt_erase(node, root, 1);
+}
+
+/**
+ * latch_tree_find() - find the node matching @key in the trees @root
+ * @key: search key
+ * @root: trees to search for @key
+ * @ops: operators defining the node order
+ *
+ * Does a lockless lookup in the trees @root for the node matching @key.
+ *
+ * It is assumed that this is called while holding the appropriate RCU read
+ * side lock.
+ *
+ * If the operators define a partial order on the elements (there are multiple
+ * elements which have the same key value) it is undefined which of these
+ * elements will be found. Nor is it possible to iterate the tree to find
+ * further elements with the same key value.
+ *
+ * Returns: a pointer to the node matching @key or NULL.
+ */
+static __always_inline struct latch_tree_node *
+latch_tree_find(void *key, struct latch_tree_root *root,
+		const struct latch_tree_ops *ops)
+{
+	struct latch_tree_node *node;
+	unsigned int seq;
+
+	do {
+		seq = raw_read_seqcount_latch(&root->seq);
+		node = __lt_find(key, root, seq & 1, ops->comp);
+	} while (read_seqcount_retry(&root->seq, seq));
+
+	return node;
+}
+
+#endif /* RB_TREE_LATCH_H */

include/linux/rcupdate.h

···
 #define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
 
 /**
- * lockless_dereference() - safely load a pointer for later dereference
- * @p: The pointer to load
- *
- * Similar to rcu_dereference(), but for situations where the pointed-to
- * object's lifetime is managed by something other than RCU.  That
- * "something other" might be reference counting or simple immortality.
- */
-#define lockless_dereference(p) \
-({ \
-	typeof(p) _________p1 = READ_ONCE(p); \
-	smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
-	(_________p1); \
-})
-
-/**
  * rcu_assign_pointer() - assign to RCU-protected pointer
  * @p: pointer to assign to
  * @v: value to assign (publish)

include/linux/seqlock.h

···
 #include <linux/spinlock.h>
 #include <linux/preempt.h>
 #include <linux/lockdep.h>
+#include <linux/compiler.h>
 #include <asm/processor.h>
 
 /*
···
 	s->sequence++;
 }
 
-/*
+static inline int raw_read_seqcount_latch(seqcount_t *s)
+{
+	return lockless_dereference(s->sequence);
+}
+
+/**
  * raw_write_seqcount_latch - redirect readers to even/odd copy
  * @s: pointer to seqcount_t
+ *
+ * The latch technique is a multiversion concurrency control method that allows
+ * queries during non-atomic modifications. If you can guarantee queries never
+ * interrupt the modification -- e.g. the concurrency is strictly between CPUs
+ * -- you most likely do not need this.
+ *
+ * Where the traditional RCU/lockless data structures rely on atomic
+ * modifications to ensure queries observe either the old or the new state the
+ * latch allows the same for non-atomic updates. The trade-off is doubling the
+ * cost of storage; we have to maintain two copies of the entire data
+ * structure.
+ *
+ * Very simply put: we first modify one copy and then the other. This ensures
+ * there is always one copy in a stable state, ready to give us an answer.
+ *
+ * The basic form is a data structure like:
+ *
+ * struct latch_struct {
+ *	seqcount_t		seq;
+ *	struct data_struct	data[2];
+ * };
+ *
+ * Where a modification, which is assumed to be externally serialized, does the
+ * following:
+ *
+ * void latch_modify(struct latch_struct *latch, ...)
+ * {
+ *	smp_wmb();	<- Ensure that the last data[1] update is visible
+ *	latch->seq++;
+ *	smp_wmb();	<- Ensure that the seqcount update is visible
+ *
+ *	modify(latch->data[0], ...);
+ *
+ *	smp_wmb();	<- Ensure that the data[0] update is visible
+ *	latch->seq++;
+ *	smp_wmb();	<- Ensure that the seqcount update is visible
+ *
+ *	modify(latch->data[1], ...);
+ * }
+ *
+ * The query will have a form like:
+ *
+ * struct entry *latch_query(struct latch_struct *latch, ...)
+ * {
+ *	struct entry *entry;
+ *	unsigned seq, idx;
+ *
+ *	do {
+ *		seq = lockless_dereference(latch->seq);
+ *
+ *		idx = seq & 0x01;
+ *		entry = data_query(latch->data[idx], ...);
+ *
+ *		smp_rmb();
+ *	} while (seq != latch->seq);
+ *
+ *	return entry;
+ * }
+ *
+ * So during the modification, queries are first redirected to data[1]. Then we
+ * modify data[0]. When that is complete, we redirect queries back to data[0]
+ * and we can modify data[1].
+ *
+ * NOTE: The non-requirement for atomic modifications does _NOT_ include
+ *       the publishing of new entries in the case where data is a dynamic
+ *       data structure.
+ *
+ *       An iteration might start in data[0] and get suspended long enough
+ *       to miss an entire modification sequence, once it resumes it might
+ *       observe the new entry.
+ *
+ * NOTE: When data is a dynamic data structure; one should use regular RCU
+ *       patterns to manage the lifetimes of the objects within.
  */
 static inline void raw_write_seqcount_latch(seqcount_t *s)
 {

init/Kconfig

···
 	bool "Compress modules on installation"
 	depends on MODULES
 	help
-	  This option compresses the kernel modules when 'make
-	  modules_install' is run.
 
-	  The modules will be compressed either using gzip or xz depend on the
-	  choice made in "Compression algorithm".
+	  Compresses kernel modules when 'make modules_install' is run; gzip or
+	  xz depending on "Compression algorithm" below.
 
-	  module-init-tools has support for gzip format while kmod handle gzip
-	  and xz compressed modules.
+	  module-init-tools MAY support gzip, and kmod MAY support gzip and xz.
 
-	  When a kernel module is installed from outside of the main kernel
-	  source and uses the Kbuild system for installing modules then that
-	  kernel module will also be compressed when it is installed.
+	  Out-of-tree kernel modules installed using Kbuild will also be
+	  compressed upon installation.
 
-	  This option provides little benefit when the modules are to be used inside
-	  an initrd or initramfs, it generally is more efficient to compress the whole
-	  initrd or initramfs instead.
+	  Note: for modules inside an initrd or initramfs, it's more efficient
+	  to compress the whole initrd or initramfs instead.
 
-	  This is fully compatible with signed modules while the signed module is
-	  compressed. module-init-tools or kmod handles decompression and provide to
-	  other layer the uncompressed but signed payload.
+	  Note: This is fully compatible with signed modules.
+
+	  If in doubt, say N.
 
 choice
 	prompt "Compression algorithm"
···
 endchoice
 
 endif # MODULES
+
+config MODULES_TREE_LOOKUP
+	def_bool y
+	depends on PERF_EVENTS || TRACING
 
 config INIT_ALL_POSSIBLE
 	bool

kernel/jump_label.c

···
 			continue;
 
 		key = iterk;
-		if (__module_address(iter->key) == mod) {
+		if (within_module(iter->key, mod)) {
 			/*
 			 * Set key->entries to iter, but preserve JUMP_LABEL_TRUE_BRANCH.
 			 */
···
 
 		key = (struct static_key *)(unsigned long)iter->key;
 
-		if (__module_address(iter->key) == mod)
+		if (within_module(iter->key, mod))
 			continue;
 
 		prev = &key->next;
···
 {
 	struct jump_entry *stop = __stop___jump_table;
 	struct jump_entry *entry = jump_label_get_entries(key);
-
 #ifdef CONFIG_MODULES
-	struct module *mod = __module_address((unsigned long)key);
+	struct module *mod;
 
 	__jump_label_mod_update(key, enable);
 
+	preempt_disable();
+	mod = __module_address((unsigned long)key);
 	if (mod)
 		stop = mod->jump_entries + mod->num_jump_entries;
+	preempt_enable();
 #endif
 	/* if there are no users, entry can be NULL */
 	if (entry)

kernel/module.c

···
 DEFINE_MUTEX(module_mutex);
 EXPORT_SYMBOL_GPL(module_mutex);
 static LIST_HEAD(modules);
+
+#ifdef CONFIG_MODULES_TREE_LOOKUP
+
+/*
+ * Use a latched RB-tree for __module_address(); this allows us to use
+ * RCU-sched lookups of the address from any context.
+ *
+ * Because modules have two address ranges: init and core, we need two
+ * latch_tree_nodes entries. Therefore we need the back-pointer from
+ * mod_tree_node.
+ *
+ * Because init ranges are short lived we mark them unlikely and have placed
+ * them outside the critical cacheline in struct module.
+ *
+ * This is conditional on PERF_EVENTS || TRACING because those can really hit
+ * __module_address() hard by doing a lot of stack unwinding; potentially from
+ * NMI context.
+ */
+
+static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
+{
+	struct mod_tree_node *mtn = container_of(n, struct mod_tree_node, node);
+	struct module *mod = mtn->mod;
+
+	if (unlikely(mtn == &mod->mtn_init))
+		return (unsigned long)mod->module_init;
+
+	return (unsigned long)mod->module_core;
+}
+
+static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)
+{
+	struct mod_tree_node *mtn = container_of(n, struct mod_tree_node, node);
+	struct module *mod = mtn->mod;
+
+	if (unlikely(mtn == &mod->mtn_init))
+		return (unsigned long)mod->init_size;
+
+	return (unsigned long)mod->core_size;
+}
+
+static __always_inline bool
+mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)
+{
+	return __mod_tree_val(a) < __mod_tree_val(b);
+}
+
+static __always_inline int
+mod_tree_comp(void *key, struct latch_tree_node *n)
+{
+	unsigned long val = (unsigned long)key;
+	unsigned long start, end;
+
+	start = __mod_tree_val(n);
+	if (val < start)
+		return -1;
+
+	end = start + __mod_tree_size(n);
+	if (val >= end)
+		return 1;
+
+	return 0;
+}
+
+static const struct latch_tree_ops mod_tree_ops = {
+	.less = mod_tree_less,
+	.comp = mod_tree_comp,
+};
+
+static struct mod_tree_root {
+	struct latch_tree_root root;
+	unsigned long addr_min;
+	unsigned long addr_max;
+} mod_tree __cacheline_aligned = {
+	.addr_min = -1UL,
+};
+
+#define module_addr_min mod_tree.addr_min
+#define module_addr_max mod_tree.addr_max
+
+static noinline void __mod_tree_insert(struct mod_tree_node *node)
+{
+	latch_tree_insert(&node->node, &mod_tree.root, &mod_tree_ops);
+}
+
+static void __mod_tree_remove(struct mod_tree_node *node)
+{
+	latch_tree_erase(&node->node, &mod_tree.root, &mod_tree_ops);
+}
+
+/*
+ * These modifications: insert, remove_init and remove; are serialized by the
+ * module_mutex.
+ */
+static void mod_tree_insert(struct module *mod)
+{
+	mod->mtn_core.mod = mod;
+	mod->mtn_init.mod = mod;
+
+	__mod_tree_insert(&mod->mtn_core);
+	if (mod->init_size)
+		__mod_tree_insert(&mod->mtn_init);
+}
+
+static void mod_tree_remove_init(struct module *mod)
+{
+	if (mod->init_size)
+		__mod_tree_remove(&mod->mtn_init);
+}
+
+static void mod_tree_remove(struct module *mod)
+{
+	__mod_tree_remove(&mod->mtn_core);
+	mod_tree_remove_init(mod);
+}
+
+static struct module *mod_find(unsigned long addr)
+{
+	struct latch_tree_node *ltn;
+
+	ltn = latch_tree_find((void *)addr, &mod_tree.root, &mod_tree_ops);
+	if (!ltn)
+		return NULL;
+
+	return container_of(ltn, struct mod_tree_node, node)->mod;
+}
+
+#else /* MODULES_TREE_LOOKUP */
+
+static unsigned long module_addr_min = -1UL, module_addr_max = 0;
+
+static void mod_tree_insert(struct module *mod) { }
+static void mod_tree_remove_init(struct module *mod) { }
+static void mod_tree_remove(struct module *mod) { }
+
+static struct module *mod_find(unsigned long addr)
+{
+	struct module *mod;
+
+	list_for_each_entry_rcu(mod, &modules, list) {
+		if (within_module(addr, mod))
+			return mod;
+	}
+
+	return NULL;
+}
+
+#endif /* MODULES_TREE_LOOKUP */
+
+/*
+ * Bounds of module text, for speeding up __module_address.
+ * Protected by module_mutex.
+ */
+static void __mod_update_bounds(void *base, unsigned int size)
+{
+	unsigned long min = (unsigned long)base;
+	unsigned long max = min + size;
+
+	if (min < module_addr_min)
+		module_addr_min = min;
+	if (max > module_addr_max)
+		module_addr_max = max;
+}
+
+static void mod_update_bounds(struct module *mod)
+{
+	__mod_update_bounds(mod->module_core, mod->core_size);
+	if (mod->init_size)
+		__mod_update_bounds(mod->module_init, mod->init_size);
+}
+
 #ifdef CONFIG_KGDB_KDB
 struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */
 #endif /* CONFIG_KGDB_KDB */
 
-#ifdef CONFIG_MODULE_SIG
-#ifdef CONFIG_MODULE_SIG_FORCE
-static bool sig_enforce = true;
-#else
-static bool sig_enforce = false;
-
-static int param_set_bool_enable_only(const char *val,
-				      const struct kernel_param *kp)
+static void module_assert_mutex(void)
 {
-	int err;
-	bool test;
-	struct kernel_param dummy_kp = *kp;
-
-	dummy_kp.arg = &test;
-
-	err = param_set_bool(val, &dummy_kp);
-	if (err)
-		return err;
-
-	/* Don't let them unset it once it's set! */
-	if (!test && sig_enforce)
-		return -EROFS;
-
-	if (test)
-		sig_enforce = true;
-	return 0;
+	lockdep_assert_held(&module_mutex);
 }
 
-static const struct kernel_param_ops param_ops_bool_enable_only = {
-	.flags = KERNEL_PARAM_OPS_FL_NOARG,
-	.set = param_set_bool_enable_only,
-	.get = param_get_bool,
-};
-#define param_check_bool_enable_only param_check_bool
+static void module_assert_mutex_or_preempt(void)
+{
+#ifdef CONFIG_LOCKDEP
+	if (unlikely(!debug_locks))
+		return;
 
+	WARN_ON(!rcu_read_lock_sched_held() &&
+		!lockdep_is_held(&module_mutex));
+#endif
+}
+
+static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
+#ifndef CONFIG_MODULE_SIG_FORCE
 module_param(sig_enforce, bool_enable_only, 0644);
 #endif /* !CONFIG_MODULE_SIG_FORCE */
-#endif /* CONFIG_MODULE_SIG */
 
 /* Block module loading/unloading? */
 int modules_disabled = 0;
···
 static DECLARE_WAIT_QUEUE_HEAD(module_wq);
 
 static BLOCKING_NOTIFIER_HEAD(module_notify_list);
-
-/* Bounds of module allocation, for speeding __module_address.
- * Protected by module_mutex. */
-static unsigned long module_addr_min = -1UL, module_addr_max = 0;
 
 int register_module_notifier(struct notifier_block *nb)
 {
···
 #endif
 	};
 
+	module_assert_mutex_or_preempt();
+
 	if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
 		return true;
 
···
 				      bool even_unformed)
 {
 	struct module *mod;
+
+	module_assert_mutex();
 
 	list_for_each_entry(mod, &modules, list) {
 		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
···
 {
 	const unsigned long *crc;
 
-	/* Since this should be found in kernel (which can't be removed),
-	 * no locking is necessary. */
+	/*
+	 * Since this should be found in kernel (which can't be removed), no
+	 * locking is necessary -- use preempt_disable() to placate lockdep.
+	 */
+	preempt_disable();
 	if (!find_symbol(VMLINUX_SYMBOL_STR(module_layout), NULL,
-			 &crc, true, false))
+			 &crc, true, false)) {
+		preempt_enable();
 		BUG();
+	}
+	preempt_enable();
 	return check_version(sechdrs, versindex,
 			     VMLINUX_SYMBOL_STR(module_layout), mod, crc,
 			     NULL);
···
 	mod_kobject_put(mod);
 }
 
+static void init_param_lock(struct module *mod)
+{
+	mutex_init(&mod->param_lock);
+}
 #else /* !CONFIG_SYSFS */
 
 static int mod_sysfs_setup(struct module *mod,
···
 {
 }
 
+static void init_param_lock(struct module *mod)
+{
+}
 #endif /* CONFIG_SYSFS */
 
 static void mod_sysfs_teardown(struct module *mod)
···
 	mutex_lock(&module_mutex);
 	/* Unlink carefully: kallsyms could be walking list. */
 	list_del_rcu(&mod->list);
+	mod_tree_remove(mod);
 	/* Remove this module from bug list, this uses list_del_rcu */
 	module_bug_cleanup(mod);
-	/* Wait for RCU synchronizing before releasing mod->list and buglist. */
-	synchronize_rcu();
+	/* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
+	synchronize_sched();
 	mutex_unlock(&module_mutex);
 
 	/* This may be NULL, but that's OK */
···
 	return vmalloc_exec(size);
 }
 
-static void *module_alloc_update_bounds(unsigned long size)
-{
-	void *ret = module_alloc(size);
-
-	if (ret) {
-		mutex_lock(&module_mutex);
-		/* Update module bounds. */
-		if ((unsigned long)ret < module_addr_min)
-			module_addr_min = (unsigned long)ret;
-		if ((unsigned long)ret + size > module_addr_max)
-			module_addr_max = (unsigned long)ret + size;
-		mutex_unlock(&module_mutex);
-	}
-	return ret;
-}
-
 #ifdef CONFIG_DEBUG_KMEMLEAK
 static void kmemleak_load_module(const struct module *mod,
 				 const struct load_info *info)
···
 	void *ptr;
 
 	/* Do the allocs. */
-	ptr = module_alloc_update_bounds(mod->core_size);
+	ptr = module_alloc(mod->core_size);
 	/*
 	 * The pointer to this block is stored in the module structure
 	 * which is inside the block. Just mark it as not being a
···
 	mod->module_core = ptr;
 
 	if (mod->init_size) {
-		ptr = module_alloc_update_bounds(mod->init_size);
+		ptr = module_alloc(mod->init_size);
 		/*
 		 * The pointer to this block is stored in the module structure
 		 * which is inside the block. This block doesn't need to be
···
 	mod->symtab = mod->core_symtab;
 	mod->strtab = mod->core_strtab;
 #endif
+	mod_tree_remove_init(mod);
 	unset_module_init_ro_nx(mod);
 	module_arch_freeing_init(mod);
 	mod->module_init = NULL;
···
 	mod->init_text_size = 0;
 	/*
 	 * We want to free module_init, but be aware that kallsyms may be
-	 * walking this with preempt disabled.  In all the failure paths,
-	 * we call synchronize_rcu/synchronize_sched, but we don't want
-	 * to slow down the success path, so use actual RCU here.
+	 * walking this with preempt disabled.  In all the failure paths, we
+	 * call synchronize_sched(), but we don't want to slow down the success
+	 * path, so use actual RCU here.
 	 */
-	call_rcu(&freeinit->rcu, do_free_init);
+	call_rcu_sched(&freeinit->rcu, do_free_init);
 	mutex_unlock(&module_mutex);
 	wake_up_all(&module_wq);
 
···
 		err = -EEXIST;
 		goto out;
 	}
+	mod_update_bounds(mod);
 	list_add_rcu(&mod->list, &modules);
+	mod_tree_insert(mod);
 	err = 0;
 
 out:
···
 	if (err)
 		goto unlink_mod;
 
+	init_param_lock(mod);
+
 	/* Now we've got everything in the final locations, we can
 	 * find optional sections. */
 	err = find_module_sections(mod, info);
···
 	/* Unlink carefully: kallsyms could be walking list. */
 	list_del_rcu(&mod->list);
 	wake_up_all(&module_wq);
-	/* Wait for RCU synchronizing before releasing mod->list. */
-	synchronize_rcu();
+	/* Wait for RCU-sched synchronizing before releasing mod->list. */
+	synchronize_sched();
 	mutex_unlock(&module_mutex);
  free_module:
 	/* Free lock-classes; relies on the preceding sync_rcu() */
···
 			    char **modname,
 			    char *namebuf)
 {
-	struct module *mod;
 	const char *ret = NULL;
+	struct module *mod;
 
 	preempt_disable();
-	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
-			continue;
-		if (within_module(addr, mod)) {
-			if (modname)
-				*modname = mod->name;
-			ret = get_ksymbol(mod, addr, size, offset);
-			break;
-		}
+	mod = __module_address(addr);
+	if (mod) {
+		if (modname)
+			*modname = mod->name;
+		ret = get_ksymbol(mod, addr, size, offset);
 	}
 	/* Make a copy in here where it's safe */
 	if (ret) {
···
 		ret = namebuf;
 	}
 	preempt_enable();
+
 	return ret;
 }
 
···
 	struct module *mod;
 	unsigned int i;
 	int ret;
+
+	module_assert_mutex();
 
 	list_for_each_entry(mod, &modules, list) {
 		if (mod->state == MODULE_STATE_UNFORMED)
···
 	if (addr < module_addr_min || addr > module_addr_max)
 		return NULL;
 
-	list_for_each_entry_rcu(mod, &modules, list) {
+	module_assert_mutex_or_preempt();
+
+	mod = mod_find(addr);
+	if (mod) {
+		BUG_ON(!within_module(addr, mod));
 		if (mod->state == MODULE_STATE_UNFORMED)
-			continue;
-		if (within_module(addr, mod))
-			return mod;
+			mod = NULL;
 	}
-	return NULL;
+	return mod;
 }
 EXPORT_SYMBOL_GPL(__module_address);
 

kernel/params.c

···
 #include <linux/slab.h>
 #include <linux/ctype.h>
 
-/* Protects all parameters, and incidentally kmalloced_param list. */
+#ifdef CONFIG_SYSFS
+/* Protects all built-in parameters, modules use their own param_lock */
 static DEFINE_MUTEX(param_lock);
+
+/* Use the module's mutex, or if built-in use the built-in mutex */
+#ifdef CONFIG_MODULES
+#define KPARAM_MUTEX(mod)	((mod) ? &(mod)->param_lock : &param_lock)
+#else
+#define KPARAM_MUTEX(mod)	(&param_lock)
+#endif
+
+static inline void check_kparam_locked(struct module *mod)
+{
+	BUG_ON(!mutex_is_locked(KPARAM_MUTEX(mod)));
+}
+#else
+static inline void check_kparam_locked(struct module *mod)
+{
+}
+#endif /* !CONFIG_SYSFS */
 
 /* This just allows us to keep track of which parameters are kmalloced. */
 struct kmalloced_param {
···
 	char val[];
 };
 static LIST_HEAD(kmalloced_params);
+static DEFINE_SPINLOCK(kmalloced_params_lock);
 
 static void *kmalloc_parameter(unsigned int size)
 {
···
 	if (!p)
 		return NULL;
 
+	spin_lock(&kmalloced_params_lock);
 	list_add(&p->list, &kmalloced_params);
+	spin_unlock(&kmalloced_params_lock);
+
 	return p->val;
 }
 
···
 {
 	struct kmalloced_param *p;
 
+	spin_lock(&kmalloced_params_lock);
 	list_for_each_entry(p, &kmalloced_params, list) {
 		if (p->val == param) {
 			list_del(&p->list);
···
 			break;
 		}
 	}
+	spin_unlock(&kmalloced_params_lock);
 }
 
 static char dash2underscore(char c)
···
 				return -EINVAL;
 			pr_debug("handling %s with %p\n", param,
 				params[i].ops->set);
-			mutex_lock(&param_lock);
+			kernel_param_lock(params[i].mod);
 			param_check_unsafe(&params[i]);
 			err = params[i].ops->set(val, &params[i]);
-			mutex_unlock(&param_lock);
+			kernel_param_unlock(params[i].mod);
 			return err;
 		}
 	}
···
 		return scnprintf(buffer, PAGE_SIZE, format,		\
 				*((type *)kp->arg));			\
 	}								\
-	struct kernel_param_ops param_ops_##name = {			\
+	const struct kernel_param_ops param_ops_##name = {			\
 		.set = param_set_##name,				\
 		.get = param_get_##name,				\
 	};								\
···
 	maybe_kfree_parameter(*((char **)arg));
 }
 
-struct kernel_param_ops param_ops_charp = {
+const struct kernel_param_ops param_ops_charp = {
 	.set = param_set_charp,
 	.get = param_get_charp,
 	.free = param_free_charp,
···
 }
 EXPORT_SYMBOL(param_get_bool);
 
-struct kernel_param_ops param_ops_bool = {
+const struct kernel_param_ops param_ops_bool = {
 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
 	.set = param_set_bool,
 	.get = param_get_bool,
 };
 EXPORT_SYMBOL(param_ops_bool);
+
+int param_set_bool_enable_only(const char *val, const struct kernel_param *kp)
+{
+	int err = 0;
+	bool new_value;
+	bool orig_value = *(bool *)kp->arg;
+	struct kernel_param dummy_kp = *kp;
+
+	dummy_kp.arg = &new_value;
+
+	err = param_set_bool(val, &dummy_kp);
+	if (err)
+		return err;
+
+	/* Don't let them unset it once it's set! */
+	if (!new_value && orig_value)
+		return -EROFS;
+
+	if (new_value)
+		err = param_set_bool(val, kp);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(param_set_bool_enable_only);
+
+const struct kernel_param_ops param_ops_bool_enable_only = {
+	.flags = KERNEL_PARAM_OPS_FL_NOARG,
+	.set = param_set_bool_enable_only,
+	.get = param_get_bool,
+};
+EXPORT_SYMBOL_GPL(param_ops_bool_enable_only);
 
 /* This one must be bool. */
 int param_set_invbool(const char *val, const struct kernel_param *kp)
···
 }
 EXPORT_SYMBOL(param_get_invbool);
 
-struct kernel_param_ops param_ops_invbool = {
+const struct kernel_param_ops param_ops_invbool = {
 	.set = param_set_invbool,
 	.get = param_get_invbool,
 };
···
 
 int param_set_bint(const char *val, const struct kernel_param *kp)
 {
-	struct kernel_param boolkp;
+	/* Match bool exactly, by re-using it. */
+	struct kernel_param boolkp = *kp;
 	bool v;
 	int ret;
 
-	/* Match bool exactly, by re-using it. */
-	boolkp = *kp;
 	boolkp.arg = &v;
 
 	ret = param_set_bool(val, &boolkp);
···
 }
 EXPORT_SYMBOL(param_set_bint);
 
-struct kernel_param_ops param_ops_bint = {
+const struct kernel_param_ops param_ops_bint = {
 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
 	.set = param_set_bint,
 	.get = param_get_int,
···
 EXPORT_SYMBOL(param_ops_bint);
 
 /* We break the rule and mangle the string. */
-static int param_array(const char *name,
+static int param_array(struct module *mod,
+		       const char *name,
 		       const char *val,
 		       unsigned int min, unsigned int max,
 		       void *elem, int elemsize,
···
 		/* nul-terminate and parse */
 		save = val[len];
 		((char *)val)[len] = '\0';
-		BUG_ON(!mutex_is_locked(&param_lock));
+		check_kparam_locked(mod);
 		ret = set(val, &kp);
 
 		if (ret != 0)
···
 	const struct kparam_array *arr = kp->arr;
 	unsigned int temp_num;
 
-	return param_array(kp->name, val, 1, arr->max, arr->elem,
+	return param_array(kp->mod, kp->name, val, 1, arr->max, arr->elem,
 			   arr->elemsize, arr->ops->set, kp->level,
 			   arr->num ?: &temp_num);
 }
···
 {
 	int i, off, ret;
 	const struct kparam_array *arr = kp->arr;
-	struct kernel_param p;
+	struct kernel_param p = *kp;
 
-	p = *kp;
 	for (i = off = 0; i < (arr->num ? *arr->num : arr->max); i++) {
 		if (i)
 			buffer[off++] = ',';
 		p.arg = arr->elem + arr->elemsize * i;
-		BUG_ON(!mutex_is_locked(&param_lock));
+		check_kparam_locked(p.mod);
 		ret = arr->ops->get(buffer + off, &p);
 		if (ret < 0)
 			return ret;
···
 			arr->ops->free(arr->elem + arr->elemsize * i);
 }
 
-struct kernel_param_ops param_array_ops = {
+const struct kernel_param_ops param_array_ops = {
 	.set = param_array_set,
 	.get = param_array_get,
 	.free = param_array_free,
···
 }
 EXPORT_SYMBOL(param_get_string);
 
-struct kernel_param_ops param_ops_string = {
+const struct kernel_param_ops param_ops_string = {
 	.set = param_set_copystring,
 	.get = param_get_string,
 };
···
 	if (!attribute->param->ops->get)
 		return -EPERM;
 
-	mutex_lock(&param_lock);
+	kernel_param_lock(mk->mod);
 	count = attribute->param->ops->get(buf, attribute->param);
-	mutex_unlock(&param_lock);
+	kernel_param_unlock(mk->mod);
 	if (count > 0) {
 		strcat(buf, "\n");
 		++count;
···
 
 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 static ssize_t param_attr_store(struct module_attribute *mattr,
-				struct module_kobject *km,
+				struct module_kobject *mk,
 				const char *buf, size_t len)
 {
  	int err;
···
 	if (!attribute->param->ops->set)
 		return -EPERM;
 
-	mutex_lock(&param_lock);
+	kernel_param_lock(mk->mod);
 	param_check_unsafe(attribute->param);
 	err = attribute->param->ops->set(buf, attribute->param);
-	mutex_unlock(&param_lock);
+	kernel_param_unlock(mk->mod);
 	if (!err)
 		return len;
 	return err;
···
 #endif
 
 #ifdef CONFIG_SYSFS
-void __kernel_param_lock(void)
+void kernel_param_lock(struct module *mod)
 {
-	mutex_lock(&param_lock);
+	mutex_lock(KPARAM_MUTEX(mod));
 }
-EXPORT_SYMBOL(__kernel_param_lock);
 
-void __kernel_param_unlock(void)
+void kernel_param_unlock(struct module *mod)
 {
-	mutex_unlock(&param_lock);
+	mutex_unlock(KPARAM_MUTEX(mod));
 }
-EXPORT_SYMBOL(__kernel_param_unlock);
+
+EXPORT_SYMBOL(kernel_param_lock);
+EXPORT_SYMBOL(kernel_param_unlock);
 
 /*
  * add_sysfs_param - add a parameter to sysfs
···
 		mk = locate_module_kobject(vattr->module_name);
 		if (mk) {
 			err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr);
+			WARN_ON_ONCE(err);
 			kobject_uevent(&mk->kobj, KOBJ_ADD);
 			kobject_put(&mk->kobj);
 		}

kernel/time/timekeeping.c

···
  * We want to use this from any context including NMI and tracing /
  * instrumenting the timekeeping code itself.
  *
- * So we handle this differently than the other timekeeping accessor
- * functions which retry when the sequence count has changed. The
- * update side does:
- *
- * smp_wmb();	<- Ensure that the last base[1] update is visible
- * tkf->seq++;
- * smp_wmb();	<- Ensure that the seqcount update is visible
- * update(tkf->base[0], tkr);
- * smp_wmb();	<- Ensure that the base[0] update is visible
- * tkf->seq++;
- * smp_wmb();	<- Ensure that the seqcount update is visible
- * update(tkf->base[1], tkr);
- *
- * The reader side does:
- *
- * do {
- *	seq = tkf->seq;
- *	smp_rmb();
- *	idx = seq & 0x01;
- *	now = now(tkf->base[idx]);
- *	smp_rmb();
- * } while (seq != tkf->seq)
- *
- * As long as we update base[0] readers are forced off to
- * base[1]. Once base[0] is updated readers are redirected to base[0]
- * and the base[1] update takes place.
+ * Employ the latch technique; see @raw_write_seqcount_latch.
  *
  * So if a NMI hits the update of base[0] then it will use base[1]
  * which is still consistent. In the worst case this can result is a
···
 	u64 now;
 
 	do {
-		seq = raw_read_seqcount(&tkf->seq);
+		seq = raw_read_seqcount_latch(&tkf->seq);
 		tkr = tkf->base + (seq & 0x01);
 		now = ktime_to_ns(tkr->base) + timekeeping_get_ns(tkr);
 	} while (read_seqcount_retry(&tkf->seq, seq));

kernel/workqueue.c

···
 module_param_named(disable_numa, wq_disable_numa, bool, 0444);
 
 /* see the comment above the definition of WQ_POWER_EFFICIENT */
-#ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
-static bool wq_power_efficient = true;
-#else
-static bool wq_power_efficient;
-#endif
-
+static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
 module_param_named(power_efficient, wq_power_efficient, bool, 0444);
 
 static bool wq_numa_enabled;		/* unbound NUMA affinity enabled */

lib/bug.c

···
 	struct module *mod;
 	const struct bug_entry *bug = NULL;
 
-	rcu_read_lock();
+	rcu_read_lock_sched();
 	list_for_each_entry_rcu(mod, &module_bug_list, bug_list) {
 		unsigned i;
 
···
 	}
 	bug = NULL;
 out:
-	rcu_read_unlock();
+	rcu_read_unlock_sched();
 
 	return bug;
 }
···
 {
 	char *secstrings;
 	unsigned int i;
+
+	lockdep_assert_held(&module_mutex);
 
 	mod->bug_table = NULL;
 	mod->num_bugs = 0;
···
 
 void module_bug_cleanup(struct module *mod)
 {
+	lockdep_assert_held(&module_mutex);
 	list_del_rcu(&mod->bug_list);
 }
 

lib/rbtree.c

···
  *  parentheses and have some accompanying text comment.
  */
 
+/*
+ * Notes on lockless lookups:
+ *
+ * All stores to the tree structure (rb_left and rb_right) must be done using
+ * WRITE_ONCE(). And we must not inadvertently cause (temporary) loops in the
+ * tree structure as seen in program order.
+ *
+ * These two requirements will allow lockless iteration of the tree -- not
+ * correct iteration mind you, tree rotations are not atomic so a lookup might
+ * miss entire subtrees.
+ *
+ * But they do guarantee that any such traversal will only see valid elements
+ * and that it will indeed complete -- does not get stuck in a loop.
+ *
+ * It also guarantees that if the lookup returns an element it is the 'correct'
+ * one. But not returning an element does _NOT_ mean it's not present.
+ *
+ * NOTE:
+ *
+ * Stores to __rb_parent_color are not important for simple lookups so those
+ * are left undone as of now. Nor did I check for loops involving parent
+ * pointers.
+ */
+
 static inline void rb_set_black(struct rb_node *rb)
 {
 	rb->__rb_parent_color |= RB_BLACK;
···
 				 * This still leaves us in violation of 4), the
 				 * continuation into Case 3 will fix that.
 				 */
-				parent->rb_right = tmp = node->rb_left;
-				node->rb_left = parent;
+				tmp = node->rb_left;
+				WRITE_ONCE(parent->rb_right, tmp);
+				WRITE_ONCE(node->rb_left, parent);
 				if (tmp)
 					rb_set_parent_color(tmp, parent,
 							    RB_BLACK);
···
 			 *     /                 \
 			 *    n                   U
 			 */
-			gparent->rb_left = tmp;  /* == parent->rb_right */
-			parent->rb_right = gparent;
+			WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */
+			WRITE_ONCE(parent->rb_right, gparent);
 			if (tmp)
 				rb_set_parent_color(tmp, gparent, RB_BLACK);
 			__rb_rotate_set_parents(gparent, parent, root, RB_RED);
···
 			tmp = parent->rb_left;
 			if (node == tmp) {
 				/* Case 2 - right rotate at parent */
-				parent->rb_left = tmp = node->rb_right;
-				node->rb_right = parent;
+				tmp = node->rb_right;
+				WRITE_ONCE(parent->rb_left, tmp);
+				WRITE_ONCE(node->rb_right, parent);
 				if (tmp)
 					rb_set_parent_color(tmp, parent,
 							    RB_BLACK);
···
 			}
 
 			/* Case 3 - left rotate at gparent */
-			gparent->rb_right = tmp;  /* == parent->rb_left */
-			parent->rb_left = gparent;
+			WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */
+			WRITE_ONCE(parent->rb_left, gparent);
 			if (tmp)
 				rb_set_parent_color(tmp, gparent, RB_BLACK);
 			__rb_rotate_set_parents(gparent, parent, root, RB_RED);
···
 				 *      / \         / \
 				 *     Sl  Sr      N   Sl
 				 */
-				parent->rb_right = tmp1 = sibling->rb_left;
-				sibling->rb_left = parent;
+				tmp1 = sibling->rb_left;
+				WRITE_ONCE(parent->rb_right, tmp1);
+				WRITE_ONCE(sibling->rb_left, parent);
 				rb_set_parent_color(tmp1, parent, RB_BLACK);
 				__rb_rotate_set_parents(parent, sibling, root,
 							RB_RED);
···
 				 *                       \
 				 *                        Sr
 				 */
-				sibling->rb_left = tmp1 = tmp2->rb_right;
-				tmp2->rb_right = sibling;
-				parent->rb_right = tmp2;
+				tmp1 = tmp2->rb_right;
+				WRITE_ONCE(sibling->rb_left, tmp1);
+				WRITE_ONCE(tmp2->rb_right, sibling);
+				WRITE_ONCE(parent->rb_right, tmp2);
 				if (tmp1)
 					rb_set_parent_color(tmp1, sibling,
 							    RB_BLACK);
···
 			 *        / \         / \
 			 *      (sl) sr      N  (sl)
 			 */
-			parent->rb_right = tmp2 = sibling->rb_left;
-			sibling->rb_left = parent;
+			tmp2 = sibling->rb_left;
+			WRITE_ONCE(parent->rb_right, tmp2);
+			WRITE_ONCE(sibling->rb_left, parent);
 			rb_set_parent_color(tmp1, sibling, RB_BLACK);
 			if (tmp2)
 				rb_set_parent(tmp2, parent);
···
 			sibling = parent->rb_left;
 			if (rb_is_red(sibling)) {
 				/* Case 1 - right rotate at parent */
-				parent->rb_left = tmp1 = sibling->rb_right;
-				sibling->rb_right = parent;
+				tmp1 = sibling->rb_right;
+				WRITE_ONCE(parent->rb_left, tmp1);
+				WRITE_ONCE(sibling->rb_right, parent);
 				rb_set_parent_color(tmp1, parent, RB_BLACK);
 				__rb_rotate_set_parents(parent, sibling, root,
 							RB_RED);
···
 					break;
 				}
 				/* Case 3 - right rotate at sibling */
-				sibling->rb_right = tmp1 = tmp2->rb_left;
-				tmp2->rb_left = sibling;
-				parent->rb_left = tmp2;
+				tmp1 = tmp2->rb_left;
+				WRITE_ONCE(sibling->rb_right, tmp1);
+				WRITE_ONCE(tmp2->rb_left, sibling);
+				WRITE_ONCE(parent->rb_left, tmp2);
 				if (tmp1)
 					rb_set_parent_color(tmp1, sibling,
 							    RB_BLACK);
···
 				sibling = tmp2;
 			}
 			/* Case 4 - left rotate at parent + color flips */
-			parent->rb_left = tmp2 = sibling->rb_right;
-			sibling->rb_right = parent;
+			tmp2 = sibling->rb_right;
+			WRITE_ONCE(parent->rb_left, tmp2);
+			WRITE_ONCE(sibling->rb_right, parent);
 			rb_set_parent_color(tmp1, sibling, RB_BLACK);
 			if (tmp2)
 				rb_set_parent(tmp2, parent);

net/mac80211/rate.c

···
 	const struct rate_control_ops *ops;
 	const char *alg_name;
 
-	kparam_block_sysfs_write(ieee80211_default_rc_algo);
+	kernel_param_lock(THIS_MODULE);
 	if (!name)
 		alg_name = ieee80211_default_rc_algo;
 	else
···
 	/* try built-in one if specific alg requested but not found */
 	if (!ops && strlen(CONFIG_MAC80211_RC_DEFAULT))
 		ops = ieee80211_try_rate_control_ops_get(CONFIG_MAC80211_RC_DEFAULT);
-	kparam_unblock_sysfs_write(ieee80211_default_rc_algo);
+	kernel_param_unlock(THIS_MODULE);
 
 	return ops;
 }

net/sunrpc/auth.c

···
 
 #define param_check_hashtbl_sz(name, p) __param_check(name, p, unsigned int);
 
-static struct kernel_param_ops param_ops_hashtbl_sz = {
+static const struct kernel_param_ops param_ops_hashtbl_sz = {
 	.set = param_set_hashtbl_sz,
 	.get = param_get_hashtbl_sz,
 };

net/sunrpc/xprtsock.c

···
 			RPC_MAX_RESVPORT);
 }
 
-static struct kernel_param_ops param_ops_portnr = {
+static const struct kernel_param_ops param_ops_portnr = {
 	.set = param_set_portnr,
 	.get = param_get_uint,
 };
···
 			RPC_MAX_SLOT_TABLE);
 }
 
-static struct kernel_param_ops param_ops_slot_table_size = {
+static const struct kernel_param_ops param_ops_slot_table_size = {
 	.set = param_set_slot_table_size,
 	.get = param_get_uint,
 };
···
 			RPC_MAX_SLOT_TABLE_LIMIT);
 }
 
-static struct kernel_param_ops param_ops_max_slot_table_size = {
+static const struct kernel_param_ops param_ops_max_slot_table_size = {
 	.set = param_set_max_slot_table_size,
 	.get = param_get_uint,
 };

security/apparmor/lsm.c

···
 static int param_set_aabool(const char *val, const struct kernel_param *kp);
 static int param_get_aabool(char *buffer, const struct kernel_param *kp);
 #define param_check_aabool param_check_bool
-static struct kernel_param_ops param_ops_aabool = {
+static const struct kernel_param_ops param_ops_aabool = {
 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
 	.set = param_set_aabool,
 	.get = param_get_aabool
···
 static int param_set_aauint(const char *val, const struct kernel_param *kp);
 static int param_get_aauint(char *buffer, const struct kernel_param *kp);
 #define param_check_aauint param_check_uint
-static struct kernel_param_ops param_ops_aauint = {
+static const struct kernel_param_ops param_ops_aauint = {
 	.set = param_set_aauint,
 	.get = param_get_aauint
 };
···
 static int param_set_aalockpolicy(const char *val, const struct kernel_param *kp);
 static int param_get_aalockpolicy(char *buffer, const struct kernel_param *kp);
 #define param_check_aalockpolicy param_check_bool
-static struct kernel_param_ops param_ops_aalockpolicy = {
+static const struct kernel_param_ops param_ops_aalockpolicy = {
 	.flags = KERNEL_PARAM_OPS_FL_NOARG,
 	.set = param_set_aalockpolicy,
 	.get = param_get_aalockpolicy

security/integrity/ima/ima_crypto.c

···
 	return 0;
 }
 
-static struct kernel_param_ops param_ops_bufsize = {
+static const struct kernel_param_ops param_ops_bufsize = {
 	.set = param_set_bufsize,
 	.get = param_get_uint,
 };

sound/pci/hda/hda_intel.c

···
 
 #ifdef CONFIG_PM
 static int param_set_xint(const char *val, const struct kernel_param *kp);
-static struct kernel_param_ops param_ops_xint = {
+static const struct kernel_param_ops param_ops_xint = {
 	.set = param_set_xint,
 	.get = param_get_int,
 };