Messages in this thread | | | Date | Mon, 05 Jun 2017 16:56:20 +0800 | From | Jia-Ju Bai <> | Subject | Re: [PATCH] fs: xfs: Fix a lock-twice and sleep-in-atomic bug in xfs_iget |
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On 06/05/2017 04:32 PM, Shan Hai wrote: > > > On 2017年06月05日 16:17, Jia-Ju Bai wrote: >> The driver may sleep under a read rcu lock, and function call path is: >> xfs_iget (acquire the lock by rcu_read_lock) >> "goto out_error_or_again" after xfs_iget_cache_hit >> delay >> schedule_timeout_uninterruptible --> may sleep >> Meanwhile, the rcu_read_lock will be called twice in this situation. >> >> To fix it, the lock is released before "goto". >> >> Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com> >> --- >> fs/xfs/xfs_icache.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c >> index f61c84f8..c2a4722 100644 >> --- a/fs/xfs/xfs_icache.c >> +++ b/fs/xfs/xfs_icache.c >> @@ -600,8 +600,10 @@ struct xfs_inode * >> if (ip) { >> error = xfs_iget_cache_hit(pag, ip, ino, flags, lock_flags); >> - if (error) >> + if (error) { >> + rcu_read_unlock(); > > Seems you are going to double unlock by doing this, since it is > unlocked in the xfs_iget_cache_hit. > > Thanks > Shan Hai > >> goto out_error_or_again; >> + } >> } else { >> rcu_read_unlock(); >> XFS_STATS_INC(mp, xs_ig_missed); > I think you are right. Please ignore my patch.
Thanks, Jia-Ju Bai
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