Merge branch 'bkl-removal' of git://git.lwn.net/linux-2.6

* 'bkl-removal' of git://git.lwn.net/linux-2.6:
Rationalize fasync return values
Move FASYNC bit handling to f_op->fasync()
Use f_lock to protect f_flags
Rename struct file->f_ep_lock

Documentation/filesystems/Locking

···
 can and should be done using the internal locking with smaller critical areas).
 Current worst offender is ext2_get_block()...
 
-->fasync() is a mess. This area needs a big cleanup and that will probably
-affect locking.
+->fasync() is called without BKL protection, and is responsible for
+maintaining the FASYNC bit in filp->f_flags.  Most instances call
+fasync_helper(), which does that maintenance, so it's not normally
+something one needs to worry about.  Return values > 0 will be mapped to
+zero in the VFS layer.
 
 ->readdir() and ->ioctl() on directories must be changed. Ideally we would
 move ->readdir() to inode_operations and use a separate method for directory

drivers/char/sonypi.c

···
 
 static int sonypi_misc_fasync(int fd, struct file *filp, int on)
 {
-	int retval;
-
-	retval = fasync_helper(fd, filp, on, &sonypi_device.fifo_async);
-	if (retval < 0)
-		return retval;
-	return 0;
+	return fasync_helper(fd, filp, on, &sonypi_device.fifo_async);
 }
 
 static int sonypi_misc_release(struct inode *inode, struct file *file)

drivers/char/tty_io.c

···
 	if (get_user(nonblock, p))
 		return -EFAULT;
 
-	/* file->f_flags is still BKL protected in the fs layer - vomit */
-	lock_kernel();
+	spin_lock(&file->f_lock);
 	if (nonblock)
 		file->f_flags |= O_NONBLOCK;
 	else
 		file->f_flags &= ~O_NONBLOCK;
-	unlock_kernel();
+	spin_unlock(&file->f_lock);
 	return 0;
 }
 

drivers/gpu/drm/drm_fops.c

···
 {
 	struct drm_file *priv = filp->private_data;
 	struct drm_device *dev = priv->minor->dev;
-	int retcode;
 
 	DRM_DEBUG("fd = %d, device = 0x%lx\n", fd,
 		  (long)old_encode_dev(priv->minor->device));
-	retcode = fasync_helper(fd, filp, on, &dev->buf_async);
-	if (retcode < 0)
-		return retcode;
-	return 0;
+	return fasync_helper(fd, filp, on, &dev->buf_async);
 }
 EXPORT_SYMBOL(drm_fasync);
 

drivers/hid/usbhid/hiddev.c

···
  */
 static int hiddev_fasync(int fd, struct file *file, int on)
 {
-	int retval;
 	struct hiddev_list *list = file->private_data;
 
-	retval = fasync_helper(fd, file, on, &list->fasync);
-
-	return retval < 0 ? retval : 0;
+	return fasync_helper(fd, file, on, &list->fasync);
 }
 
 

drivers/ieee1394/dv1394.c

···
 
 	struct video_card *video = file_to_video_card(file);
 
-	int retval = fasync_helper(fd, file, on, &video->fasync);
-
-	if (retval < 0)
-		return retval;
-        return 0;
+	return fasync_helper(fd, file, on, &video->fasync);
 }
 
 static ssize_t dv1394_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)

drivers/input/evdev.c

···
 static int evdev_fasync(int fd, struct file *file, int on)
 {
 	struct evdev_client *client = file->private_data;
-	int retval;
 
-	retval = fasync_helper(fd, file, on, &client->fasync);
-
-	return retval < 0 ? retval : 0;
+	return fasync_helper(fd, file, on, &client->fasync);
 }
 
 static int evdev_flush(struct file *file, fl_owner_t id)

drivers/input/joydev.c

···
 
 static int joydev_fasync(int fd, struct file *file, int on)
 {
-	int retval;
 	struct joydev_client *client = file->private_data;
 
-	retval = fasync_helper(fd, file, on, &client->fasync);
-
-	return retval < 0 ? retval : 0;
+	return fasync_helper(fd, file, on, &client->fasync);
 }
 
 static void joydev_free(struct device *dev)

drivers/input/mousedev.c

···
 
 static int mousedev_fasync(int fd, struct file *file, int on)
 {
-	int retval;
 	struct mousedev_client *client = file->private_data;
 
-	retval = fasync_helper(fd, file, on, &client->fasync);
-
-	return retval < 0 ? retval : 0;
+	return fasync_helper(fd, file, on, &client->fasync);
 }
 
 static void mousedev_free(struct device *dev)

drivers/input/serio/serio_raw.c

···
 static int serio_raw_fasync(int fd, struct file *file, int on)
 {
 	struct serio_raw_list *list = file->private_data;
-	int retval;
 
-	retval = fasync_helper(fd, file, on, &list->fasync);
-	return retval < 0 ? retval : 0;
+	return fasync_helper(fd, file, on, &list->fasync);
 }
 
 static struct serio_raw *serio_raw_locate(int minor)

drivers/net/wan/cosa.c

···
 static int cosa_fasync(struct inode *inode, struct file *file, int on)
 {
         int port = iminor(inode);
-        int rv = fasync_helper(inode, file, on, &fasync[port]);
-        return rv < 0 ? rv : 0;
+
+	return fasync_helper(inode, file, on, &fasync[port]);
 }
 #endif
 

drivers/platform/x86/sony-laptop.c

···
 
 static int sonypi_misc_fasync(int fd, struct file *filp, int on)
 {
-	int retval;
-
-	retval = fasync_helper(fd, filp, on, &sonypi_compat.fifo_async);
-	if (retval < 0)
-		return retval;
-	return 0;
+	return fasync_helper(fd, filp, on, &sonypi_compat.fifo_async);
 }
 
 static int sonypi_misc_release(struct inode *inode, struct file *file)

drivers/scsi/sg.c

···
 static int
 sg_fasync(int fd, struct file *filp, int mode)
 {
-	int retval;
 	Sg_device *sdp;
 	Sg_fd *sfp;
 
···
 	SCSI_LOG_TIMEOUT(3, printk("sg_fasync: %s, mode=%d\n",
 				   sdp->disk->disk_name, mode));
 
-	retval = fasync_helper(fd, filp, mode, &sfp->async_qp);
-	return (retval < 0) ? retval : 0;
+	return fasync_helper(fd, filp, mode, &sfp->async_qp);
 }
 
 static int

drivers/usb/gadget/file_storage.c

···
 		curlun->sense_data = SS_WRITE_PROTECTED;
 		return -EINVAL;
 	}
+	spin_lock(&curlun->filp->f_lock);
 	curlun->filp->f_flags &= ~O_SYNC;	// Default is not to wait
+	spin_unlock(&curlun->filp->f_lock);
 
 	/* Get the starting Logical Block Address and check that it's
 	 * not too big */
···
 			curlun->sense_data = SS_INVALID_FIELD_IN_CDB;
 			return -EINVAL;
 		}
-		if (fsg->cmnd[1] & 0x08)	// FUA
+		if (fsg->cmnd[1] & 0x08) {	// FUA
+			spin_lock(&curlun->filp->f_lock);
 			curlun->filp->f_flags |= O_SYNC;
+			spin_unlock(&curlun->filp->f_lock);
+		}
 	}
 	if (lba >= curlun->num_sectors) {
 		curlun->sense_data = SS_LOGICAL_BLOCK_ADDRESS_OUT_OF_RANGE;

fs/eventpoll.c

···
 	ep_unregister_pollwait(ep, epi);
 
 	/* Remove the current item from the list of epoll hooks */
-	spin_lock(&file->f_ep_lock);
+	spin_lock(&file->f_lock);
 	if (ep_is_linked(&epi->fllink))
 		list_del_init(&epi->fllink);
-	spin_unlock(&file->f_ep_lock);
+	spin_unlock(&file->f_lock);
 
 	rb_erase(&epi->rbn, &ep->rbr);
 
···
 	struct epitem *epi;
 
 	/*
-	 * We don't want to get "file->f_ep_lock" because it is not
+	 * We don't want to get "file->f_lock" because it is not
 	 * necessary. It is not necessary because we're in the "struct file"
 	 * cleanup path, and this means that noone is using this file anymore.
 	 * So, for example, epoll_ctl() cannot hit here sicne if we reach this
···
 	 * will correctly serialize the operation. We do need to acquire
 	 * "ep->mtx" after "epmutex" because ep_remove() requires it when called
 	 * from anywhere but ep_free().
+	 *
+	 * Besides, ep_remove() acquires the lock, so we can't hold it here.
 	 */
 	mutex_lock(&epmutex);
 
···
 		goto error_unregister;
 
 	/* Add the current item to the list of active epoll hook for this file */
-	spin_lock(&tfile->f_ep_lock);
+	spin_lock(&tfile->f_lock);
 	list_add_tail(&epi->fllink, &tfile->f_ep_links);
-	spin_unlock(&tfile->f_ep_lock);
+	spin_unlock(&tfile->f_lock);
 
 	/*
 	 * Add the current item to the RB tree. All RB tree operations are

fs/fcntl.c

···
 	return ret;
 }
 
-#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME)
+#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
 
 static int setfl(int fd, struct file * filp, unsigned long arg)
 {
···
 		return error;
 
 	/*
-	 * We still need a lock here for now to keep multiple FASYNC calls
-	 * from racing with each other.
+	 * ->fasync() is responsible for setting the FASYNC bit.
 	 */
-	lock_kernel();
-	if ((arg ^ filp->f_flags) & FASYNC) {
-		if (filp->f_op && filp->f_op->fasync) {
-			error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
-			if (error < 0)
-				goto out;
-		}
+	if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
+			filp->f_op->fasync) {
+		error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
+		if (error < 0)
+			goto out;
+		if (error > 0)
+			error = 0;
 	}
-
+	spin_lock(&filp->f_lock);
 	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
+	spin_unlock(&filp->f_lock);
+
  out:
-	unlock_kernel();
 	return error;
 }
 
···
 static struct kmem_cache *fasync_cache __read_mostly;
 
 /*
- * fasync_helper() is used by some character device drivers (mainly mice)
+ * fasync_helper() is used by almost all character device drivers
  * to set up the fasync queue. It returns negative on error, 0 if it did
  * no changes and positive if it added/deleted the entry.
  */
···
 		result = 1;
 	}
 out:
+	/* Fix up FASYNC bit while still holding fasync_lock */
+	spin_lock(&filp->f_lock);
+	if (on)
+		filp->f_flags |= FASYNC;
+	else
+		filp->f_flags &= ~FASYNC;
+	spin_unlock(&filp->f_lock);
 	write_unlock_irq(&fasync_lock);
 	return result;
 }

fs/file_table.c

···
 	atomic_long_set(&f->f_count, 1);
 	rwlock_init(&f->f_owner.lock);
 	f->f_cred = get_cred(cred);
+	spin_lock_init(&f->f_lock);
 	eventpoll_init_file(f);
 	/* f->f_version: 0 */
 	return f;

fs/ioctl.c

···
 	if (O_NONBLOCK != O_NDELAY)
 		flag |= O_NDELAY;
 #endif
+	spin_lock(&filp->f_lock);
 	if (on)
 		filp->f_flags |= flag;
 	else
 		filp->f_flags &= ~flag;
+	spin_unlock(&filp->f_lock);
 	return error;
 }
 
···
 	/* Did FASYNC state change ? */
 	if ((flag ^ filp->f_flags) & FASYNC) {
 		if (filp->f_op && filp->f_op->fasync)
+			/* fasync() adjusts filp->f_flags */
 			error = filp->f_op->fasync(fd, filp, on);
 		else
 			error = -ENOTTY;
 	}
-	if (error)
-		return error;
-
-	if (on)
-		filp->f_flags |= FASYNC;
-	else
-		filp->f_flags &= ~FASYNC;
-	return error;
+	return error < 0 ? error : 0;
 }
 
 static int ioctl_fsfreeze(struct file *filp)
···
 		break;
 
 	case FIONBIO:
-		/* BKL needed to avoid races tweaking f_flags */
-		lock_kernel();
 		error = ioctl_fionbio(filp, argp);
-		unlock_kernel();
 		break;
 
 	case FIOASYNC:
-		/* BKL needed to avoid races tweaking f_flags */
-		lock_kernel();
 		error = ioctl_fioasync(fd, filp, argp);
-		unlock_kernel();
 		break;
 
 	case FIOQSIZE:

fs/nfsd/vfs.c

···
 
 	if (!EX_ISSYNC(exp))
 		stable = 0;
-	if (stable && !EX_WGATHER(exp))
+	if (stable && !EX_WGATHER(exp)) {
+		spin_lock(&file->f_lock);
 		file->f_flags |= O_SYNC;
+		spin_unlock(&file->f_lock);
+	}
 
 	/* Write the data. */
 	oldfs = get_fs(); set_fs(KERNEL_DS);

fs/pipe.c

···
 	retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
 	mutex_unlock(&inode->i_mutex);
 
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 
···
 	retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
 	mutex_unlock(&inode->i_mutex);
 
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 
···
 			fasync_helper(-1, filp, 0, &pipe->fasync_readers);
 	}
 	mutex_unlock(&inode->i_mutex);
-
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 

include/linux/eventpoll.h

···
 static inline void eventpoll_init_file(struct file *file)
 {
 	INIT_LIST_HEAD(&file->f_ep_links);
-	spin_lock_init(&file->f_ep_lock);
 }
 
 

include/linux/fs.h

···
 #define f_dentry	f_path.dentry
 #define f_vfsmnt	f_path.mnt
 	const struct file_operations	*f_op;
+	spinlock_t		f_lock;  /* f_ep_links, f_flags */
 	atomic_long_t		f_count;
 	unsigned int 		f_flags;
 	fmode_t			f_mode;
···
 #ifdef CONFIG_EPOLL
 	/* Used by fs/eventpoll.c to link all the hooks to this file */
 	struct list_head	f_ep_links;
-	spinlock_t		f_ep_lock;
 #endif /* #ifdef CONFIG_EPOLL */
 	struct address_space	*f_mapping;
 #ifdef CONFIG_DEBUG_WRITECOUNT

ipc/mqueue.c

···
 	omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
 	if (u_mqstat) {
 		audit_mq_getsetattr(mqdes, &mqstat);
+		spin_lock(&filp->f_lock);
 		if (mqstat.mq_flags & O_NONBLOCK)
 			filp->f_flags |= O_NONBLOCK;
 		else
 			filp->f_flags &= ~O_NONBLOCK;
+		spin_unlock(&filp->f_lock);
 
 		inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	}

net/socket.c

···
 
 	lock_sock(sk);
 
+	spin_lock(&filp->f_lock);
+	if (on)
+		filp->f_flags |= FASYNC;
+	else
+		filp->f_flags &= ~FASYNC;
+	spin_unlock(&filp->f_lock);
+
 	prev = &(sock->fasync_list);
 
 	for (fa = *prev; fa != NULL; prev = &fa->fa_next, fa = *prev)

sound/core/control.c

···
 static int snd_ctl_fasync(int fd, struct file * file, int on)
 {
 	struct snd_ctl_file *ctl;
-	int err;
+
 	ctl = file->private_data;
-	err = fasync_helper(fd, file, on, &ctl->fasync);
-	if (err < 0)
-		return err;
-	return 0;
+	return fasync_helper(fd, file, on, &ctl->fasync);
 }
 
 /*

sound/core/oss/pcm_oss.c

···
 
 static int snd_pcm_oss_nonblock(struct file * file)
 {
+	spin_lock(&file->f_lock);
 	file->f_flags |= O_NONBLOCK;
+	spin_unlock(&file->f_lock);
 	return 0;
 }
 

sound/core/pcm_native.c

···
 	err = fasync_helper(fd, file, on, &runtime->fasync);
 out:
 	unlock_kernel();
-	if (err < 0)
-		return err;
-	return 0;
+	return err;
 }
 
 /*

sound/core/timer.c

···
 static int snd_timer_user_fasync(int fd, struct file * file, int on)
 {
 	struct snd_timer_user *tu;
-	int err;
 
 	tu = file->private_data;
-	err = fasync_helper(fd, file, on, &tu->fasync);
-        if (err < 0)
-		return err;
-	return 0;
+	return fasync_helper(fd, file, on, &tu->fasync);
 }
 
 static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,

sound/oss/au1550_ac97.c

···
 				    sizeof(abinfo)) ? -EFAULT : 0;
 
 	case SNDCTL_DSP_NONBLOCK:
+		spin_lock(&file->f_lock);
 		file->f_flags |= O_NONBLOCK;
+		spin_unlock(&file->f_lock);
 		return 0;
 
 	case SNDCTL_DSP_GETODELAY:

sound/oss/audio.c

···
 			return dma_ioctl(dev, cmd, arg);
 		
 		case SNDCTL_DSP_NONBLOCK:
+			spin_lock(&file->f_lock);
 			file->f_flags |= O_NONBLOCK;
+			spin_unlock(&file->f_lock);
 			return 0;
 
 		case SNDCTL_DSP_GETCAPS:

sound/oss/sh_dac_audio.c

···
 		return put_user(AFMT_U8, (int *)arg);
 
 	case SNDCTL_DSP_NONBLOCK:
+		spin_lock(&file->f_lock);
 		file->f_flags |= O_NONBLOCK;
+		spin_unlock(&file->f_lock);
 		return 0;
 
 	case SNDCTL_DSP_GETCAPS:

sound/oss/swarm_cs4297a.c

···
 				    sizeof(abinfo)) ? -EFAULT : 0;
 
 	case SNDCTL_DSP_NONBLOCK:
+		spin_lock(&file->f_lock);
 		file->f_flags |= O_NONBLOCK;
+		spin_unlock(&file->f_lock);
 		return 0;
 
 	case SNDCTL_DSP_GETODELAY:

sound/oss/vwsnd.c

···
 
 	case SNDCTL_DSP_NONBLOCK:	/* _SIO  ('P',14) */
 		DBGX("SNDCTL_DSP_NONBLOCK\n");
+		spin_lock(&file->f_lock);
 		file->f_flags |= O_NONBLOCK;
+		spin_unlock(&file->f_lock);
 		return 0;
 
 	case SNDCTL_DSP_RESET:		/* _SIO  ('P', 0) */