From: Pranay Srivastava <pranjas@gmail.com>
To: Markus Pargmann <mpa@pengutronix.de>,
nbd-general@lists.sourceforge.net, linux-kernel@vger.kernel.org,
Wouter Verhelst <w@uter.be>
Cc: "Pranay Kr. Srivastava" <pranjas@gmail.com>
Subject: Re: [PATCH v3 1/3]nbd: fix might_sleep warning on socket shutdown
Date: Tue, 28 Jun 2016 11:12:26 +0530 [thread overview]
Message-ID: <CA+aCy1F69v6uD7-9+ff6Gqf0GytB0BgTcnwDyuJZxwRsCGc8HA@mail.gmail.com> (raw)
In-Reply-To: <1466762976-12648-2-git-send-email-pranjas@gmail.com>
Hi Markus,
On Fri, Jun 24, 2016 at 3:39 PM, Pranay Kr. Srivastava
<pranjas@gmail.com> wrote:
> 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 <mikulas@twibright.com>
> Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
>
> Changelog:
> Pranay Kr. Srivastava<pranjas@gmail.com>:
>
> 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 <pranjas@gmail.com>
> ---
> 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 <asm/types.h>
>
> #include <linux/nbd.h>
> +#include <linux/workqueue.h>
>
> 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
>
Do you think this series can be reviewed for 4.7?
--
---P.K.S
next prev parent reply other threads:[~2016-06-28 5:42 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-24 11:26 [PATCH 0/4]nbd: fixes for nbd Pranay Kr. Srivastava
2016-05-24 11:26 ` [PATCH 1/4] fix might_sleep warning on socket shutdown Pranay Kr. Srivastava
2016-05-30 12:06 ` Markus Pargmann
2016-05-24 11:26 ` [PATCH 2/4] fix various coding standard warnings Pranay Kr. Srivastava
2016-05-24 11:26 ` [PATCH 3/4] make nbd device wait for its users Pranay Kr. Srivastava
2016-05-30 10:44 ` Markus Pargmann
2016-05-24 11:26 ` [PATCH 4/4] use device_attr macros for sysfs attribute Pranay Kr. Srivastava
2016-05-30 3:35 ` [PATCH 0/4]nbd: fixes for nbd Pranay Srivastava
2016-05-30 12:27 ` Markus Pargmann
2016-06-02 10:24 ` [PATCH v2 0/5] nbd: " Pranay Kr. Srivastava
2016-06-02 10:24 ` [PATCH v2 1/5] nbd: fix might_sleep warning on socket shutdown Pranay Kr. Srivastava
2016-06-09 10:03 ` Pranay Srivastava
2016-06-14 5:13 ` Pranay Srivastava
2016-06-14 8:52 ` Markus Pargmann
2016-06-14 9:50 ` Pranay Srivastava
2016-06-24 10:09 ` [PATCH v3 0/3] nbd: resolve bugs and limitations Pranay Kr. Srivastava
2016-06-24 10:09 ` [PATCH v3 1/3]nbd: fix might_sleep warning on socket shutdown Pranay Kr. Srivastava
2016-06-28 5:42 ` Pranay Srivastava [this message]
2016-06-29 7:18 ` Markus Pargmann
2016-06-24 10:09 ` [PATCH v3 2/3]nbd: cleanup nbd_set_socket Pranay Kr. Srivastava
2016-06-24 10:09 ` [PATCH 3/3]nbd: make nbd device wait for its users Pranay Kr. Srivastava
2016-06-24 13:42 ` [Nbd] " Eric Blake
2016-06-25 17:56 ` Pranay Srivastava
2016-06-25 18:01 ` Pranay Srivastava
2016-06-29 7:06 ` Markus Pargmann
2016-06-29 7:15 ` Pranay Srivastava
2016-06-02 10:24 ` [PATCH v2 2/5]nbd: cleanup nbd_set_socket Pranay Kr. Srivastava
2016-06-02 10:24 ` [PATCH v2 3/5]nbd: fix various coding standard warnings Pranay Kr. Srivastava
2016-06-02 10:25 ` [PATCH v2 4/5]nbd: make nbd device wait for its users Pranay Kr. Srivastava
2016-06-14 8:59 ` Markus Pargmann
2016-06-14 9:33 ` Pranay Srivastava
2016-06-15 6:30 ` Markus Pargmann
2016-06-15 7:00 ` [Nbd] " Wouter Verhelst
2016-06-15 9:18 ` Pranay Srivastava
2016-06-15 9:17 ` Pranay Srivastava
2016-06-24 9:29 ` [PATCH 1/2] nbd: " Markus Pargmann
2016-06-24 9:29 ` [PATCH 2/2] nbd: Disallow ioctls on disconnected block device Markus Pargmann
2016-07-16 7:42 ` Pranay Srivastava
2016-07-16 9:32 ` [Nbd] " Alex Bligh
2016-07-16 10:08 ` Pranay Srivastava
2016-07-16 11:26 ` Wouter Verhelst
2016-07-16 13:31 ` Pranay Srivastava
2016-06-24 9:39 ` [PATCH 1/2] nbd: make nbd device wait for its users Pranay Srivastava
2016-06-24 13:40 ` [Nbd] " Eric Blake
2016-06-25 17:52 ` Pranay Srivastava
2016-06-29 6:57 ` Markus Pargmann
2016-06-02 10:25 ` [PATCH v2 5/5]nbd: use device_attr macros for sysfs attribute Pranay Kr. Srivastava
[not found] ` <CA+aCy1E0S4ofa04xcO9qxQmuipaF5wdnrv3ubSvETn-rBYYisA@mail.gmail.com>
2016-06-06 11:07 ` [PATCH 0/4]nbd: fixes for nbd Pranay Srivastava
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