240 lines
7.3 KiB
Diff
240 lines
7.3 KiB
Diff
From: Markus Pargmann <mpa@pengutronix.de>
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Date: Mon, 17 Aug 2015 08:20:00 +0200
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Subject: nbd: Fix timeout detection
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Origin: https://git.kernel.org/linus/7e2893a16d3e71035a38122a77bc55848a29f0e4
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Bug-Debian: https://bugs.debian.org/770479
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At the moment the nbd timeout just detects hanging tcp operations. This
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is not enough to detect a hanging or bad connection as expected of a
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timeout.
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This patch redesigns the timeout detection to include some more cases.
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The timeout is now in relation to replies from the server. If the server
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does not send replies within the timeout the connection will be shut
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down.
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The patch adds a continous timer 'timeout_timer' that is setup in one of
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two cases:
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- The request list is empty and we are sending the first request out to
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the server. We want to have a reply within the given timeout,
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otherwise we consider the connection to be dead.
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- A server response was received. This means the server is still
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communicating with us. The timer is reset to the timeout value.
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The timer is not stopped if the list becomes empty. It will just trigger
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a timeout which will directly leave the handling routine again as the
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request list is empty.
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The whole patch does not use any additional explicit locking. The
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list_empty() calls are safe to be used concurrently. The timer is locked
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internally as we just use mod_timer and del_timer_sync().
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The patch is based on the idea of Michal Belczyk with a previous
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different implementation.
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Cc: Michal Belczyk <belczyk@bsd.krakow.pl>
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Cc: Hermann Lauer <Hermann.Lauer@iwr.uni-heidelberg.de>
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Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
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Tested-by: Hermann Lauer <Hermann.Lauer@iwr.uni-heidelberg.de>
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Signed-off-by: Jens Axboe <axboe@fb.com>
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---
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drivers/block/nbd.c | 98 ++++++++++++++++++++++++++++++++++++++---------------
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1 file changed, 70 insertions(+), 28 deletions(-)
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diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
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index f169faf..f3536e6 100644
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--- a/drivers/block/nbd.c
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+++ b/drivers/block/nbd.c
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@@ -59,6 +59,10 @@ struct nbd_device {
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pid_t pid; /* pid of nbd-client, if attached */
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int xmit_timeout;
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int disconnect; /* a disconnect has been requested by user */
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+
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+ struct timer_list timeout_timer;
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+ struct task_struct *task_recv;
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+ struct task_struct *task_send;
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};
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#define NBD_MAGIC 0x68797548
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@@ -121,6 +125,7 @@ static void sock_shutdown(struct nbd_device *nbd, int lock)
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dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");
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kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
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nbd->sock = NULL;
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+ del_timer_sync(&nbd->timeout_timer);
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}
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if (lock)
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mutex_unlock(&nbd->tx_lock);
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@@ -128,11 +133,23 @@ static void sock_shutdown(struct nbd_device *nbd, int lock)
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static void nbd_xmit_timeout(unsigned long arg)
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{
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- struct task_struct *task = (struct task_struct *)arg;
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+ struct nbd_device *nbd = (struct nbd_device *)arg;
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+ struct task_struct *task;
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+
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+ if (list_empty(&nbd->queue_head))
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+ return;
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+
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+ nbd->disconnect = 1;
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+
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+ task = READ_ONCE(nbd->task_recv);
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+ if (task)
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+ force_sig(SIGKILL, task);
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- printk(KERN_WARNING "nbd: killing hung xmit (%s, pid: %d)\n",
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- task->comm, task->pid);
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- force_sig(SIGKILL, task);
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+ task = READ_ONCE(nbd->task_send);
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+ if (task)
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+ force_sig(SIGKILL, nbd->task_send);
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+
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+ dev_err(nbd_to_dev(nbd), "Connection timed out, killed receiver and sender, shutting down connection\n");
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}
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/*
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@@ -171,33 +188,12 @@ static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
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msg.msg_controllen = 0;
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msg.msg_flags = msg_flags | MSG_NOSIGNAL;
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- if (send) {
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- struct timer_list ti;
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-
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- if (nbd->xmit_timeout) {
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- init_timer(&ti);
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- ti.function = nbd_xmit_timeout;
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- ti.data = (unsigned long)current;
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- ti.expires = jiffies + nbd->xmit_timeout;
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- add_timer(&ti);
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- }
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+ if (send)
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result = kernel_sendmsg(sock, &msg, &iov, 1, size);
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- if (nbd->xmit_timeout)
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- del_timer_sync(&ti);
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- } else
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+ else
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result = kernel_recvmsg(sock, &msg, &iov, 1, size,
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msg.msg_flags);
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- if (signal_pending(current)) {
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- siginfo_t info;
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- printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
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- task_pid_nr(current), current->comm,
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- dequeue_signal_lock(current, ¤t->blocked, &info));
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- result = -EINTR;
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- sock_shutdown(nbd, !send);
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- break;
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- }
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-
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if (result <= 0) {
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if (result == 0)
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result = -EPIPE; /* short read */
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@@ -210,6 +206,9 @@ static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,
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sigprocmask(SIG_SETMASK, &oldset, NULL);
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tsk_restore_flags(current, pflags, PF_MEMALLOC);
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+ if (!send && nbd->xmit_timeout)
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+ mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
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+
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return result;
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}
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@@ -415,12 +414,26 @@ static int nbd_do_it(struct nbd_device *nbd)
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return ret;
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}
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+ nbd->task_recv = current;
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+
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while ((req = nbd_read_stat(nbd)) != NULL)
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nbd_end_request(nbd, req);
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+ nbd->task_recv = NULL;
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+
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+ if (signal_pending(current)) {
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+ siginfo_t info;
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+
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+ ret = dequeue_signal_lock(current, ¤t->blocked, &info);
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+ dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
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+ task_pid_nr(current), current->comm, ret);
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+ sock_shutdown(nbd, 1);
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+ ret = -ETIMEDOUT;
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+ }
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+
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device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
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nbd->pid = 0;
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- return 0;
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+ return ret;
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}
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static void nbd_clear_que(struct nbd_device *nbd)
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@@ -482,6 +495,9 @@ static void nbd_handle_req(struct nbd_device *nbd, struct request *req)
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nbd->active_req = req;
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+ if (nbd->xmit_timeout && list_empty_careful(&nbd->queue_head))
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+ mod_timer(&nbd->timeout_timer, jiffies + nbd->xmit_timeout);
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+
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if (nbd_send_req(nbd, req) != 0) {
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dev_err(disk_to_dev(nbd->disk), "Request send failed\n");
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req->errors++;
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@@ -508,6 +524,8 @@ static int nbd_thread(void *data)
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struct nbd_device *nbd = data;
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struct request *req;
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+ nbd->task_send = current;
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+
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set_user_nice(current, MIN_NICE);
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while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) {
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/* wait for something to do */
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@@ -515,6 +533,18 @@ static int nbd_thread(void *data)
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kthread_should_stop() ||
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!list_empty(&nbd->waiting_queue));
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+ if (signal_pending(current)) {
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+ siginfo_t info;
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+ int ret;
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+
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+ ret = dequeue_signal_lock(current, ¤t->blocked,
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+ &info);
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+ dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n",
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+ task_pid_nr(current), current->comm, ret);
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+ sock_shutdown(nbd, 1);
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+ break;
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+ }
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+
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/* extract request */
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if (list_empty(&nbd->waiting_queue))
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continue;
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@@ -528,6 +558,9 @@ static int nbd_thread(void *data)
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/* handle request */
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nbd_handle_req(nbd, req);
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}
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+
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+ nbd->task_send = NULL;
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+
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return 0;
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}
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@@ -648,6 +681,12 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
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case NBD_SET_TIMEOUT:
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nbd->xmit_timeout = arg * HZ;
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+ if (arg)
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+ mod_timer(&nbd->timeout_timer,
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+ jiffies + nbd->xmit_timeout);
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+ else
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+ del_timer_sync(&nbd->timeout_timer);
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+
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return 0;
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case NBD_SET_FLAGS:
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@@ -842,6 +881,9 @@ static int __init nbd_init(void)
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spin_lock_init(&nbd_dev[i].queue_lock);
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INIT_LIST_HEAD(&nbd_dev[i].queue_head);
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mutex_init(&nbd_dev[i].tx_lock);
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+ init_timer(&nbd_dev[i].timeout_timer);
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+ nbd_dev[i].timeout_timer.function = nbd_xmit_timeout;
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+ nbd_dev[i].timeout_timer.data = (unsigned long)&nbd_dev[i];
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init_waitqueue_head(&nbd_dev[i].active_wq);
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init_waitqueue_head(&nbd_dev[i].waiting_wq);
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nbd_dev[i].blksize = 1024;
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