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author | Trond Myklebust <Trond.Myklebust@netapp.com> | 2006-11-13 21:23:44 (GMT) |
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committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2006-12-06 15:46:26 (GMT) |
commit | 8aca67f0ae2d8811165c22326825a645cc8e1b48 (patch) | |
tree | 19e82f4bc7b4f865a9dcf4744e7c224ea517ba10 /net | |
parent | e6b3c4db6fbcd0d33720696f37790d6b8be12313 (diff) | |
download | linux-fsl-qoriq-8aca67f0ae2d8811165c22326825a645cc8e1b48.tar.xz |
SUNRPC: Fix a potential race in rpc_wake_up_task()
Use RCU to ensure that we can safely call rpc_finish_wakeup after we've
called __rpc_do_wake_up_task. If not, there is a theoretical race, in which
the rpc_task finishes executing, and gets freed first.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'net')
-rw-r--r-- | net/sunrpc/sched.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 66d01365..6b808c0 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -427,16 +427,19 @@ __rpc_default_timer(struct rpc_task *task) */ void rpc_wake_up_task(struct rpc_task *task) { + rcu_read_lock_bh(); if (rpc_start_wakeup(task)) { if (RPC_IS_QUEUED(task)) { struct rpc_wait_queue *queue = task->u.tk_wait.rpc_waitq; - spin_lock_bh(&queue->lock); + /* Note: we're already in a bh-safe context */ + spin_lock(&queue->lock); __rpc_do_wake_up_task(task); - spin_unlock_bh(&queue->lock); + spin_unlock(&queue->lock); } rpc_finish_wakeup(task); } + rcu_read_unlock_bh(); } /* @@ -499,14 +502,16 @@ struct rpc_task * rpc_wake_up_next(struct rpc_wait_queue *queue) struct rpc_task *task = NULL; dprintk("RPC: wake_up_next(%p \"%s\")\n", queue, rpc_qname(queue)); - spin_lock_bh(&queue->lock); + rcu_read_lock_bh(); + spin_lock(&queue->lock); if (RPC_IS_PRIORITY(queue)) task = __rpc_wake_up_next_priority(queue); else { task_for_first(task, &queue->tasks[0]) __rpc_wake_up_task(task); } - spin_unlock_bh(&queue->lock); + spin_unlock(&queue->lock); + rcu_read_unlock_bh(); return task; } @@ -522,7 +527,8 @@ void rpc_wake_up(struct rpc_wait_queue *queue) struct rpc_task *task, *next; struct list_head *head; - spin_lock_bh(&queue->lock); + rcu_read_lock_bh(); + spin_lock(&queue->lock); head = &queue->tasks[queue->maxpriority]; for (;;) { list_for_each_entry_safe(task, next, head, u.tk_wait.list) @@ -531,7 +537,8 @@ void rpc_wake_up(struct rpc_wait_queue *queue) break; head--; } - spin_unlock_bh(&queue->lock); + spin_unlock(&queue->lock); + rcu_read_unlock_bh(); } /** @@ -546,7 +553,8 @@ void rpc_wake_up_status(struct rpc_wait_queue *queue, int status) struct rpc_task *task, *next; struct list_head *head; - spin_lock_bh(&queue->lock); + rcu_read_lock_bh(); + spin_lock(&queue->lock); head = &queue->tasks[queue->maxpriority]; for (;;) { list_for_each_entry_safe(task, next, head, u.tk_wait.list) { @@ -557,7 +565,8 @@ void rpc_wake_up_status(struct rpc_wait_queue *queue, int status) break; head--; } - spin_unlock_bh(&queue->lock); + spin_unlock(&queue->lock); + rcu_read_unlock_bh(); } static void __rpc_atrun(struct rpc_task *task) @@ -817,8 +826,9 @@ rpc_alloc_task(void) return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS); } -static void rpc_free_task(struct rpc_task *task) +static void rpc_free_task(struct rcu_head *rcu) { + struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu); dprintk("RPC: %4d freeing task\n", task->tk_pid); mempool_free(task, rpc_task_mempool); } @@ -872,7 +882,7 @@ void rpc_put_task(struct rpc_task *task) task->tk_client = NULL; } if (task->tk_flags & RPC_TASK_DYNAMIC) - rpc_free_task(task); + call_rcu_bh(&task->u.tk_rcu, rpc_free_task); if (tk_ops->rpc_release) tk_ops->rpc_release(calldata); } |