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authorYihao Wu <wuyihao@linux.alibaba.com>2019-05-22 01:57:10 +0800
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2019-05-30 15:36:24 -0400
commit52b042ab9948cc367b61f9ca9c18603aa7813c3a (patch)
tree30972007c92d57b1a71c049bfffe840f0a1946a2 /fs
parent7987b694ade8cc465ce10fb3dceaa614f13ceaf3 (diff)
downloadlwn-52b042ab9948cc367b61f9ca9c18603aa7813c3a.tar.gz
lwn-52b042ab9948cc367b61f9ca9c18603aa7813c3a.zip
NFSv4.1: Again fix a race where CB_NOTIFY_LOCK fails to wake a waiter
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> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/nfs/nfs4proc.c24
1 files changed, 7 insertions, 17 deletions
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index c29cbef6b53f..5f89bbd177c6 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 @@ nfs4_wake_lock_waiter(wait_queue_entry_t *wait, unsigned int mode, int flags, vo
/* 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 @@ static int
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 @@ nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
.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 @@ nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
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);