From: Yihao Wu <wuyihao@linux.alibaba.com>
To: linux-nfs@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>, caspar@linux.alibaba.com
Subject: [PATCH v3 1/2] NFSv4.1: Again fix a race where CB_NOTIFY_LOCK fails to wake a waiter
Date: Wed, 22 May 2019 01:57:10 +0800 [thread overview]
Message-ID: <37564b2e-9167-a7c1-6f12-8fffaad088fb@linux.alibaba.com> (raw)
In-Reply-To: <48a9d50b-f7b9-407d-06db-5c9079dfbf24@linux.alibaba.com>
Commit b7dbcc0e433f "NFSv4.1: Fix a race where CB_NOTIFY_LOCK fails to wake a waiter"
found this bug. However it didn't fix it.
This commit replaces schedule_timeout() with wait_woken() and
default_wake_function() with woken_wake_function() in function
nfs4_retry_setlk() and nfs4_wake_lock_waiter(). wait_woken() uses
memory barriers in its implementation to avoid potential race condition
when putting a process into sleeping state and then waking it up.
Fixes: a1d617d8f134 ("nfs: allow blocking locks to be awoken by lock callbacks")
Cc: stable@vger.kernel.org #4.9+
Signed-off-by: Yihao Wu <wuyihao@linux.alibaba.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
---
v2->v3: remove unused variable flags in nfs4_retry_setlk()
fs/nfs/nfs4proc.c | 24 +++++++-----------------
1 file changed, 7 insertions(+), 17 deletions(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c29cbef..5f89bbd 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6932,7 +6932,6 @@ struct nfs4_lock_waiter {
struct task_struct *task;
struct inode *inode;
struct nfs_lowner *owner;
- bool notified;
};
static int
@@ -6954,13 +6953,13 @@ struct nfs4_lock_waiter {
/* Make sure it's for the right inode */
if (nfs_compare_fh(NFS_FH(waiter->inode), &cbnl->cbnl_fh))
return 0;
-
- waiter->notified = true;
}
/* override "private" so we can use default_wake_function */
wait->private = waiter->task;
- ret = autoremove_wake_function(wait, mode, flags, key);
+ ret = woken_wake_function(wait, mode, flags, key);
+ if (ret)
+ list_del_init(&wait->entry);
wait->private = waiter;
return ret;
}
@@ -6969,7 +6968,6 @@ struct nfs4_lock_waiter {
nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
{
int status = -ERESTARTSYS;
- unsigned long flags;
struct nfs4_lock_state *lsp = request->fl_u.nfs4_fl.owner;
struct nfs_server *server = NFS_SERVER(state->inode);
struct nfs_client *clp = server->nfs_client;
@@ -6979,8 +6977,7 @@ struct nfs4_lock_waiter {
.s_dev = server->s_dev };
struct nfs4_lock_waiter waiter = { .task = current,
.inode = state->inode,
- .owner = &owner,
- .notified = false };
+ .owner = &owner};
wait_queue_entry_t wait;
/* Don't bother with waitqueue if we don't expect a callback */
@@ -6993,21 +6990,14 @@ struct nfs4_lock_waiter {
add_wait_queue(q, &wait);
while(!signalled()) {
- waiter.notified = false;
status = nfs4_proc_setlk(state, cmd, request);
if ((status != -EAGAIN) || IS_SETLK(cmd))
break;
status = -ERESTARTSYS;
- spin_lock_irqsave(&q->lock, flags);
- if (waiter.notified) {
- spin_unlock_irqrestore(&q->lock, flags);
- continue;
- }
- set_current_state(TASK_INTERRUPTIBLE);
- spin_unlock_irqrestore(&q->lock, flags);
-
- freezable_schedule_timeout(NFS4_LOCK_MAXTIMEOUT);
+ freezer_do_not_count();
+ wait_woken(&wait, TASK_INTERRUPTIBLE, NFS4_LOCK_MAXTIMEOUT);
+ freezer_count();
}
finish_wait(q, &wait);
--
1.8.3.1
next prev parent reply other threads:[~2019-05-21 17:57 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-13 6:49 [PATCH v2 0/2] Fix two bugs CB_NOTIFY_LOCK failing to wake a water Yihao Wu
2019-05-13 6:57 ` [PATCH v2 1/2] NFSv4.1: Again fix a race where CB_NOTIFY_LOCK fails to wake a waiter Yihao Wu
2019-05-17 9:22 ` Joseph Qi
2019-05-17 14:04 ` Yihao Wu
2019-05-21 17:57 ` Yihao Wu [this message]
2019-05-13 6:58 ` [PATCH v2 2/2] NFSv4.1: Fix bug only first CB_NOTIFY_LOCK is handled Yihao Wu
2019-05-13 13:36 ` [PATCH v2 0/2] Fix two bugs CB_NOTIFY_LOCK failing to wake a water Jeff Layton
2019-05-16 8:01 ` Yihao Wu
2019-05-16 11:47 ` Jeff Layton
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