Messages in this thread Patch in this message | | | From | Fabian Frederick <> | Subject | [PATCH 1/1 linux-next] fs/ufs/super.c: fix potential race condition | Date | Tue, 3 Feb 2015 18:03:34 +0100 |
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Let locking subsystem decide on mutex management. As reported by Andrew Morton this patch fixes a bug:
" lock_ufs() is assuming that on non-preempt uniprocessor, the calling code will run atomically up to the matching unlock_ufs().
But that isn't true. The very first site I looked at (ufs_frag_map) does sb_bread() under lock_ufs(). And sb_bread() will call schedule(), very commonly.
The ->mutex_owner stuff is a bit hacky but should work OK. "
Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> --- fs/ufs/super.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/fs/ufs/super.c b/fs/ufs/super.c index e515e99..8092d37 100644 --- a/fs/ufs/super.c +++ b/fs/ufs/super.c @@ -95,22 +95,18 @@ void lock_ufs(struct super_block *sb) { -#if defined(CONFIG_SMP) || defined (CONFIG_PREEMPT) struct ufs_sb_info *sbi = UFS_SB(sb); mutex_lock(&sbi->mutex); sbi->mutex_owner = current; -#endif } void unlock_ufs(struct super_block *sb) { -#if defined(CONFIG_SMP) || defined (CONFIG_PREEMPT) struct ufs_sb_info *sbi = UFS_SB(sb); sbi->mutex_owner = NULL; mutex_unlock(&sbi->mutex); -#endif } static struct inode *ufs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation) -- 2.1.0
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