From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751460AbcFXKJ7 (ORCPT ); Fri, 24 Jun 2016 06:09:59 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:33497 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751001AbcFXKJz (ORCPT ); Fri, 24 Jun 2016 06:09:55 -0400 From: "Pranay Kr. Srivastava" To: mpa@pengutronix.de, nbd-general@lists.sourceforge.net, linux-kernel@vger.kernel.org, w@uter.be Cc: "Pranay Kr. Srivastava" Subject: [PATCH v3 1/3]nbd: fix might_sleep warning on socket shutdown Date: Fri, 24 Jun 2016 13:09:34 +0300 Message-Id: <1466762976-12648-2-git-send-email-pranjas@gmail.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1466762976-12648-1-git-send-email-pranjas@gmail.com> References: <1962682.lYRJ5o9hTF@adelgunde> <1466762976-12648-1-git-send-email-pranjas@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org spinlocked ranges should be small and not contain calls into huge subfunctions. Fix my mistake and just get the pointer to the socket instead of doing everything with spinlock held. Reported-by: Mikulas Patocka Signed-off-by: Markus Pargmann Changelog: Pranay Kr. Srivastava: 1) Use spin_lock instead of irq version for sock_shutdown. 2) Use system work queue to actually trigger the shutdown of socket. This solves the issue when kernel_sendmsg is currently blocked while a timeout occurs. Signed-off-by: Pranay Kr. Srivastava --- drivers/block/nbd.c | 69 ++++++++++++++++++++++++++++++++++------------------- 1 file changed, 44 insertions(+), 25 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 56f7f5d..586d946 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -39,6 +39,7 @@ #include #include +#include struct nbd_device { u32 flags; @@ -69,6 +70,10 @@ struct nbd_device { #if IS_ENABLED(CONFIG_DEBUG_FS) struct dentry *dbg_dir; #endif + /* + *This is specifically for calling sock_shutdown, for now. + */ + struct work_struct ws_shutdown; }; #if IS_ENABLED(CONFIG_DEBUG_FS) @@ -95,6 +100,11 @@ static int max_part; */ static DEFINE_SPINLOCK(nbd_lock); +/* + * Shutdown function for nbd_dev work struct. + */ +static void nbd_ws_func_shutdown(struct work_struct *); + static inline struct device *nbd_to_dev(struct nbd_device *nbd) { return disk_to_dev(nbd->disk); @@ -172,39 +182,35 @@ static void nbd_end_request(struct nbd_device *nbd, struct request *req) */ static void sock_shutdown(struct nbd_device *nbd) { - spin_lock_irq(&nbd->sock_lock); - - if (!nbd->sock) { - spin_unlock_irq(&nbd->sock_lock); - return; - } + struct socket *sock; - dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); - kernel_sock_shutdown(nbd->sock, SHUT_RDWR); - sockfd_put(nbd->sock); + spin_lock(&nbd->sock_lock); + sock = nbd->sock; nbd->sock = NULL; - spin_unlock_irq(&nbd->sock_lock); + spin_unlock(&nbd->sock_lock); + + if (!sock) + return; del_timer(&nbd->timeout_timer); + dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n"); + kernel_sock_shutdown(sock, SHUT_RDWR); + sockfd_put(sock); } static void nbd_xmit_timeout(unsigned long arg) { struct nbd_device *nbd = (struct nbd_device *)arg; - unsigned long flags; if (list_empty(&nbd->queue_head)) return; - - spin_lock_irqsave(&nbd->sock_lock, flags); - nbd->timedout = true; - - if (nbd->sock) - kernel_sock_shutdown(nbd->sock, SHUT_RDWR); - - spin_unlock_irqrestore(&nbd->sock_lock, flags); - + schedule_work(&nbd->ws_shutdown); + /* + * Make sure sender thread sees nbd->timedout. + */ + smp_wmb(); + wake_up(&nbd->waiting_wq); dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n"); } @@ -574,8 +580,8 @@ static int nbd_thread_send(void *data) while (!kthread_should_stop() || !list_empty(&nbd->waiting_queue)) { /* wait for something to do */ wait_event_interruptible(nbd->waiting_wq, - kthread_should_stop() || - !list_empty(&nbd->waiting_queue)); + kthread_should_stop() || + !list_empty(&nbd->waiting_queue)); /* extract request */ if (list_empty(&nbd->waiting_queue)) @@ -583,12 +589,16 @@ static int nbd_thread_send(void *data) spin_lock_irq(&nbd->queue_lock); req = list_entry(nbd->waiting_queue.next, struct request, - queuelist); + queuelist); list_del_init(&req->queuelist); spin_unlock_irq(&nbd->queue_lock); - /* handle request */ nbd_handle_req(nbd, req); + if (nbd->timedout) { + req->errors++; + nbd_end_request(nbd, req); + } else + nbd_handle_req(nbd, req); } nbd->task_send = NULL; @@ -668,6 +678,7 @@ static void nbd_reset(struct nbd_device *nbd) set_capacity(nbd->disk, 0); nbd->flags = 0; nbd->xmit_timeout = 0; + INIT_WORK(&nbd->ws_shutdown, nbd_ws_func_shutdown); queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue); del_timer_sync(&nbd->timeout_timer); } @@ -802,11 +813,11 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, error = nbd_thread_recv(nbd, bdev); nbd_dev_dbg_close(nbd); kthread_stop(thread); + sock_shutdown(nbd); mutex_lock(&nbd->tx_lock); nbd->task_recv = NULL; - sock_shutdown(nbd); nbd_clear_que(nbd); kill_bdev(bdev); nbd_bdev_reset(bdev); @@ -862,6 +873,14 @@ static const struct block_device_operations nbd_fops = { .compat_ioctl = nbd_ioctl, }; +static void nbd_ws_func_shutdown(struct work_struct *ws_nbd) +{ + struct nbd_device *nbd_dev = container_of(ws_nbd, struct nbd_device, + ws_shutdown); + + sock_shutdown(nbd_dev); +} + #if IS_ENABLED(CONFIG_DEBUG_FS) static int nbd_dbg_tasks_show(struct seq_file *s, void *unused) -- 1.9.1