Messages in this thread | | | Subject | Re: [PATCH] fs: xfs: Fix a lock-twice and sleep-in-atomic bug in xfs_iget | From | Shan Hai <> | Date | Mon, 5 Jun 2017 16:32:48 +0800 |
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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);
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