Messages in this thread Patch in this message |  | | Date | Thu, 9 Nov 2000 03:20:57 -0800 | From | "David S. Miller" <> | Subject | Re: [patch] NE2000 |
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Date: Thu, 09 Nov 2000 21:53:42 +1100 From: Andrew Morton <andrewm@uow.edu.au>
"David S. Miller" wrote: > I will compose a patch to fix all this.
I've quickly been through just about all of the kernel wrt waitqueues.
My analysis was in error, BEWARE!
Being on multiple wait queues at once is just fine. I verified this with Linus tonight.
The problem case is in mixing TASK_EXCLUSIVE and non-TASK_EXCLUSIVE sleeps, that is what can actually cause problems.
Everything else is fine. Anyways, the (untested) patch below should cure the lock_sock() cases.
--- ./net/ipv4/af_inet.c.~1~ Tue Oct 24 14:26:18 2000 +++ ./net/ipv4/af_inet.c Wed Nov 8 17:28:47 2000 @@ -543,24 +543,27 @@ { DECLARE_WAITQUEUE(wait, current); - __set_current_state(TASK_INTERRUPTIBLE); - add_wait_queue(sk->sleep, &wait); - /* Basic assumption: if someone sets sk->err, he _must_ * change state of the socket from TCP_SYN_*. * Connect() does not allow to get error notifications * without closing the socket. */ while ((1<<sk->state)&(TCPF_SYN_SENT|TCPF_SYN_RECV)) { + __set_current_state(TASK_INTERRUPTIBLE); + add_wait_queue(sk->sleep, &wait); + release_sock(sk); - timeo = schedule_timeout(timeo); + + if ((1<<sk->state)&(TCPF_SYN_SENT|TCPF_SYN_RECV)) + timeo = schedule_timeout(timeo); + + __set_current_state(TASK_RUNNING); + remove_wait_queue(sk->sleep, &wait); + lock_sock(sk); if (signal_pending(current) || !timeo) break; - set_current_state(TASK_INTERRUPTIBLE); } - __set_current_state(TASK_RUNNING); - remove_wait_queue(sk->sleep, &wait); return timeo; } --- ./net/ipv4/tcp.c.~1~ Fri Oct 6 15:45:41 2000 +++ ./net/ipv4/tcp.c Wed Nov 8 17:35:31 2000 @@ -826,10 +826,12 @@ release_sock(sk); *timeo_p = schedule_timeout(*timeo_p); - lock_sock(sk); __set_task_state(tsk, TASK_RUNNING); remove_wait_queue(sk->sleep, &wait); + + lock_sock(sk); + sk->tp_pinfo.af_tcp.write_pending--; } return 0; @@ -854,24 +856,31 @@ clear_bit(SOCK_ASYNC_NOSPACE, &sk->socket->flags); - add_wait_queue(sk->sleep, &wait); for (;;) { set_bit(SOCK_NOSPACE, &sk->socket->flags); + add_wait_queue(sk->sleep, &wait); set_current_state(TASK_INTERRUPTIBLE); - if (signal_pending(current)) - break; - if (tcp_memory_free(sk) && !vm_wait) - break; - if (sk->shutdown & SEND_SHUTDOWN) - break; - if (sk->err) + if (signal_pending(current) || + (tcp_memory_free(sk) && !vm_wait) || + (sk->shutdown & SEND_SHUTDOWN) || + sk->err) { + current->state = TASK_RUNNING; + remove_wait_queue(sk->sleep, &wait); break; + } + release_sock(sk); + if (!tcp_memory_free(sk) || vm_wait) current_timeo = schedule_timeout(current_timeo); + + current->state = TASK_RUNNING; + remove_wait_queue(sk->sleep, &wait); + lock_sock(sk); + if (vm_wait) { if (timeo != MAX_SCHEDULE_TIMEOUT && (timeo -= vm_wait-current_timeo) < 0) @@ -881,8 +890,6 @@ timeo = current_timeo; } } - current->state = TASK_RUNNING; - remove_wait_queue(sk->sleep, &wait); return timeo; } @@ -1266,7 +1273,6 @@ DECLARE_WAITQUEUE(wait, current); add_wait_queue(sk->sleep, &wait); - __set_current_state(TASK_INTERRUPTIBLE); set_bit(SOCK_ASYNC_WAITDATA, &sk->socket->flags); @@ -1275,11 +1281,12 @@ if (skb_queue_empty(&sk->receive_queue)) timeo = schedule_timeout(timeo); + remove_wait_queue(sk->sleep, &wait); + __set_current_state(TASK_RUNNING); + lock_sock(sk); clear_bit(SOCK_ASYNC_WAITDATA, &sk->socket->flags); - remove_wait_queue(sk->sleep, &wait); - __set_current_state(TASK_RUNNING); return timeo; } @@ -1826,19 +1833,23 @@ struct task_struct *tsk = current; DECLARE_WAITQUEUE(wait, current); - add_wait_queue(sk->sleep, &wait); - do { + add_wait_queue(sk->sleep, &wait); set_current_state(TASK_INTERRUPTIBLE); - if (!closing(sk)) + if (!closing(sk)) { + tsk->state = TASK_RUNNING; + remove_wait_queue(sk->sleep, &wait); break; + } release_sock(sk); + timeout = schedule_timeout(timeout); + + tsk->state = TASK_RUNNING; + remove_wait_queue(sk->sleep, &wait); + lock_sock(sk); } while (!signal_pending(tsk) && timeout); - - tsk->state = TASK_RUNNING; - remove_wait_queue(sk->sleep, &wait); } adjudge_to_death: @@ -2009,12 +2020,17 @@ * our exclusiveness temporarily when we get woken up without * having to remove and re-insert us on the wait queue. */ - add_wait_queue_exclusive(sk->sleep, &wait); for (;;) { + add_wait_queue_exclusive(sk->sleep, &wait); current->state = TASK_EXCLUSIVE | TASK_INTERRUPTIBLE; + release_sock(sk); if (sk->tp_pinfo.af_tcp.accept_queue == NULL) timeo = schedule_timeout(timeo); + + current->state = TASK_RUNNING; + remove_wait_queue(sk->sleep, &wait); + lock_sock(sk); err = 0; if (sk->tp_pinfo.af_tcp.accept_queue) @@ -2029,8 +2045,6 @@ if (!timeo) break; } - current->state = TASK_RUNNING; - remove_wait_queue(sk->sleep, &wait); return err; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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