scsi: ufs: core: Make fault injection dynamically configurable per HBA

The UFS driver has two driver-specific fault injection mechanisms
(trigger_eh and timeout). Each fault injection configuration can only be
specified by a module parameter and cannot be reconfigured without
reloading the driver. Also, each configuration is common to all HBAs.

This change adds the following subdirectories for each UFS HBA when
debugfs is enabled:

/sys/kernel/debug/ufshcd/<HBA>/timeout_inject
/sys/kernel/debug/ufshcd/<HBA>/trigger_eh_inject

Each fault injection attribute can be dynamically set per HBA by a
corresponding file in these directories.

This is tested with QEMU UFS devices.

Signed-off-by: Akinobu Mita <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/ufs/core/ufs-fault-injection.c

···
 #include <linux/types.h>
 #include <linux/fault-inject.h>
 #include <linux/module.h>
+#include <ufs/ufshcd.h>
 #include "ufs-fault-injection.h"
 
 static int ufs_fault_get(char *buffer, const struct kernel_param *kp);
···
 	return 0;
 }
 
-bool ufs_trigger_eh(void)
+void ufs_fault_inject_hba_init(struct ufs_hba *hba)
 {
-	return should_fail(&ufs_trigger_eh_attr, 1);
+	hba->trigger_eh_attr = ufs_trigger_eh_attr;
+	hba->timeout_attr = ufs_timeout_attr;
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+	fault_create_debugfs_attr("trigger_eh_inject", hba->debugfs_root, &hba->trigger_eh_attr);
+	fault_create_debugfs_attr("timeout_inject", hba->debugfs_root, &hba->timeout_attr);
+#endif
 }
 
-bool ufs_fail_completion(void)
+bool ufs_trigger_eh(struct ufs_hba *hba)
 {
-	return should_fail(&ufs_timeout_attr, 1);
+	return should_fail(&hba->trigger_eh_attr, 1);
+}
+
+bool ufs_fail_completion(struct ufs_hba *hba)
+{
+	return should_fail(&hba->timeout_attr, 1);
 }

drivers/ufs/core/ufs-fault-injection.h

···
 #include <linux/types.h>
 
 #ifdef CONFIG_SCSI_UFS_FAULT_INJECTION
-bool ufs_trigger_eh(void);
-bool ufs_fail_completion(void);
+void ufs_fault_inject_hba_init(struct ufs_hba *hba);
+bool ufs_trigger_eh(struct ufs_hba *hba);
+bool ufs_fail_completion(struct ufs_hba *hba);
 #else
-static inline bool ufs_trigger_eh(void)
+static inline void ufs_fault_inject_hba_init(struct ufs_hba *hba)
+{
+}
+
+static inline bool ufs_trigger_eh(struct ufs_hba *hba)
 {
 	return false;
 }
 
-static inline bool ufs_fail_completion(void)
+static inline bool ufs_fail_completion(struct ufs_hba *hba)
 {
 	return false;
 }

drivers/ufs/core/ufshcd.c

···
 	ufshcd_send_command(hba, tag, hwq);
 
 out:
-	if (ufs_trigger_eh()) {
+	if (ufs_trigger_eh(hba)) {
 		unsigned long flags;
 
 		spin_lock_irqsave(hba->host->host_lock, flags);
···
 	    !(hba->quirks & UFSHCI_QUIRK_SKIP_RESET_INTR_AGGR))
 		ufshcd_reset_intr_aggr(hba);
 
-	if (ufs_fail_completion())
+	if (ufs_fail_completion(hba))
 		return IRQ_HANDLED;
 
 	/*
···
 		goto out_disable_vreg;
 
 	ufs_debugfs_hba_init(hba);
+	ufs_fault_inject_hba_init(hba);
 
 	hba->is_powered = true;
 	goto out;

include/ufs/ufshcd.h

···
 #include <linux/blk-crypto-profile.h>
 #include <linux/blk-mq.h>
 #include <linux/devfreq.h>
+#include <linux/fault-inject.h>
 #include <linux/msi.h>
 #include <linux/pm_runtime.h>
 #include <linux/dma-direction.h>
···
 	struct dentry *debugfs_root;
 	struct delayed_work debugfs_ee_work;
 	u32 debugfs_ee_rate_limit_ms;
+#endif
+#ifdef CONFIG_SCSI_UFS_FAULT_INJECTION
+	struct fault_attr trigger_eh_attr;
+	struct fault_attr timeout_attr;
 #endif
 	u32 luns_avail;
 	unsigned int nr_hw_queues;