diff options
| author | Zhang Xiaoxu <zhangxiaoxu5@huawei.com> | 2021-06-26 15:50:41 +0800 |
|---|---|---|
| committer | Trond Myklebust <trond.myklebust@hammerspace.com> | 2021-06-28 09:34:39 -0400 |
| commit | fcb170a9d825d7db4a3fb870b0300f5a40a8d096 (patch) | |
| tree | 171c63b1fab9dc492a643c6142c96b230492bae2 /net/sunrpc | |
| parent | b42ad64f5f216db05310783cbded56176c3a09df (diff) | |
SUNRPC: Fix the batch tasks count wraparound.
The 'queue->nr' will wraparound from 0 to 255 when only current
priority queue has tasks. This maybe lead a deadlock same as commit
dfe1fe75e00e ("NFSv4: Fix deadlock between nfs4_evict_inode()
and nfs4_opendata_get_inode()"):
Privileged delegreturn task is queued to privileged list because all
the slots are assigned. When non-privileged task complete and release
the slot, a non-privileged maybe picked out. It maybe allocate slot
failed when the session on draining.
If the 'queue->nr' has wraparound to 255, and no enough slot to
service it, then the privileged delegreturn will lost to wake up.
So we should avoid the wraparound on 'queue->nr'.
Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 5fcdfacc01f3 ("NFSv4: Return delegations synchronously in evict_inode")
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/sched.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 39ed0e0afe6d..71993adb0762 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -595,7 +595,8 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q * Service a batch of tasks from a single owner. */ q = &queue->tasks[queue->priority]; - if (!list_empty(q) && --queue->nr) { + if (!list_empty(q) && queue->nr) { + queue->nr--; task = list_first_entry(q, struct rpc_task, u.tk_wait.list); goto out; } |