From d05fdb0cec75415b2d9eb95748386e67414e49c3 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 22 Jun 2005 17:16:19 +0000 Subject: [PATCH] [PATCH] RPC: Fix a race with rpc_restart_call() 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 Signed-off-by: Trond Myklebust --- net/sunrpc/sched.c | 53 ++++++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 23 deletions(-) diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index c06614d0e3..cc298fa4b8 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -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; -- 2.39.5