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[PATCH] RPC: Fix a race with rpc_restart_call()

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If the task->tk_exit() wants to restart the RPC call after delaying
 then the current RPC code will clobber the timer by calling
 rpc_delete_timer() immediately after re-entering the loop in
 __rpc_execute().

 Problem noticed by Oleg Nesterov <oleg@tv-sign.ru>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2005-06-22 17:16:19 +00:00
parent 4e93d3e885
commit d05fdb0cec
1 changed files with 30 additions and 23 deletions
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53
net/sunrpc/sched.c
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@ -554,6 +554,30 @@ __rpc_atrun(struct rpc_task *task)
rpc_wake_up_task(task);
}
/*
* Helper that calls task->tk_exit if it exists and then returns
* true if we should exit __rpc_execute.
*/
static inline int __rpc_do_exit(struct rpc_task *task)
{
if (task->tk_exit != NULL) {
lock_kernel();
task->tk_exit(task);
unlock_kernel();
/* If tk_action is non-null, we should restart the call */
if (task->tk_action != NULL) {
if (!RPC_ASSASSINATED(task)) {
/* Release RPC slot and buffer memory */
xprt_release(task);
rpc_free(task);
return 0;
}
printk(KERN_ERR "RPC: dead task tried to walk away.\n");
}
}
return 1;
}
/*
* This is the RPC `scheduler' (or rather, the finite state machine).
*/
@ -566,8 +590,7 @@ static int __rpc_execute(struct rpc_task *task)
BUG_ON(RPC_IS_QUEUED(task));
restarted:
while (1) {
for (;;) {
/*
* Garbage collection of pending timers...
*/
@ -600,11 +623,12 @@ static int __rpc_execute(struct rpc_task *task)
* by someone else.
*/
if (!RPC_IS_QUEUED(task)) {
if (!task->tk_action)
if (task->tk_action != NULL) {
lock_kernel();
task->tk_action(task);
unlock_kernel();
} else if (__rpc_do_exit(task))
break;
lock_kernel();
task->tk_action(task);
unlock_kernel();
}
/*
@ -645,23 +669,6 @@ static int __rpc_execute(struct rpc_task *task)
dprintk("RPC: %4d sync task resuming\n", task->tk_pid);
}
if (task->tk_exit) {
lock_kernel();
task->tk_exit(task);
unlock_kernel();
/* If tk_action is non-null, the user wants us to restart */
if (task->tk_action) {
if (!RPC_ASSASSINATED(task)) {
/* Release RPC slot and buffer memory */
if (task->tk_rqstp)
xprt_release(task);
rpc_free(task);
goto restarted;
}
printk(KERN_ERR "RPC: dead task tries to walk away.\n");
}
}
dprintk("RPC: %4d exit() = %d\n", task->tk_pid, task->tk_status);
status = task->tk_status;