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| author | Jonathan Corbet <corbet@lwn.net> | 2009-03-27 12:24:31 -0600 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2009-03-30 08:00:24 -0600 |
| commit | 4a6a4499693a419a20559c41e33a7bd70bf20a6f (patch) | |
| tree | 7a89d08f0b2f19e1b84b38869596c8a84ab6f583 | |
| parent | 996ff68d8b358885c1de82a45517c607999947c7 (diff) | |
| download | linux-3.10-4a6a4499693a419a20559c41e33a7bd70bf20a6f.tar.gz linux-3.10-4a6a4499693a419a20559c41e33a7bd70bf20a6f.tar.bz2 linux-3.10-4a6a4499693a419a20559c41e33a7bd70bf20a6f.zip | |
Fix a lockdep warning in fasync_helper()
Lockdep gripes if file->f_lock is taken in a no-IRQ situation, since that
is not always the case. We don't really want to disable IRQs for every
acquisition of f_lock; instead, just move it outside of fasync_lock.
Reported-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Reported-by: Larry Finger <Larry.Finger@lwfinger.net>
Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
| -rw-r--r-- | fs/fcntl.c | 10 | ||||
| -rw-r--r-- | include/linux/fs.h | 2 |
2 files changed, 8 insertions, 4 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c index d865ca66ccb..cc8e4de2fee 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -531,6 +531,12 @@ int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fap if (!new) return -ENOMEM; } + + /* + * We need to take f_lock first since it's not an IRQ-safe + * lock. + */ + spin_lock(&filp->f_lock); write_lock_irq(&fasync_lock); for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { if (fa->fa_file == filp) { @@ -555,14 +561,12 @@ int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fap 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); + spin_unlock(&filp->f_lock); return result; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 7428c6d35e6..2f13c1d7781 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -848,7 +848,7 @@ struct file { #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 */ + spinlock_t f_lock; /* f_ep_links, f_flags, no IRQ */ atomic_long_t f_count; unsigned int f_flags; fmode_t f_mode; |