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Subject[RESEND PATCH]nbd: fix might_sleep warning on socket shutdown
Date
This patch fixes the warning generated when a timeout occurs
on the request and socket is closed from a non-sleep context
by

1. Moving the socket closing on a timeout to nbd_thread_send

2. Make sock lock to be a mutex instead of a spin lock, since
nbd_xmit_timeout doesn't need to hold it anymore.

3. Move sock_shutdown outside the tx_lock in NBD_DO_IT.
---
drivers/block/nbd.c | 85 +++++++++++++++++++++++++++++++----------------------
1 file changed, 50 insertions(+), 35 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 31e73a7..a52cc16 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -3,7 +3,7 @@
*
* Note that you can not swap over this thing, yet. Seems to work but
* deadlocks sometimes - you can not swap over TCP in general.
- *
+ *
* Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
* Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
*
@@ -35,14 +35,14 @@
#include <linux/types.h>
#include <linux/debugfs.h>

-#include <asm/uaccess.h>
+#include <linux/uaccess.h>
#include <asm/types.h>

#include <linux/nbd.h>

struct nbd_device {
u32 flags;
- struct socket * sock; /* If == NULL, device is not ready, yet */
+ struct socket *sock; /* If == NULL, device is not ready, yet */
int magic;

spinlock_t queue_lock;
@@ -57,12 +57,12 @@ struct nbd_device {
int blksize;
loff_t bytesize;
int xmit_timeout;
- bool timedout;
+ atomic_t timedout;
bool disconnect; /* a disconnect has been requested by user */

struct timer_list timeout_timer;
/* protects initialization and shutdown of the socket */
- spinlock_t sock_lock;
+ struct mutex sock_lock;
struct task_struct *task_recv;
struct task_struct *task_send;

@@ -172,10 +172,9 @@ 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);
-
+ mutex_lock(&nbd->sock_lock);
if (!nbd->sock) {
- spin_unlock_irq(&nbd->sock_lock);
+ mutex_unlock(&nbd->sock_lock);
return;
}

@@ -183,27 +182,19 @@ static void sock_shutdown(struct nbd_device *nbd)
kernel_sock_shutdown(nbd->sock, SHUT_RDWR);
sockfd_put(nbd->sock);
nbd->sock = NULL;
- spin_unlock_irq(&nbd->sock_lock);
-
+ mutex_unlock(&nbd->sock_lock);
del_timer(&nbd->timeout_timer);
}

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);
+ atomic_inc(&nbd->timedout);
+ wake_up(&nbd->waiting_wq);

dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n");
}
@@ -266,6 +257,7 @@ static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,
{
int result;
void *kaddr = kmap(bvec->bv_page);
+
result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,
bvec->bv_len, flags);
kunmap(bvec->bv_page);
@@ -278,6 +270,7 @@ static int nbd_send_req(struct nbd_device *nbd, struct request *req)
int result, flags;
struct nbd_request request;
unsigned long size = blk_rq_bytes(req);
+
u32 type;

if (req->cmd_type == REQ_TYPE_DRV_PRIV)
@@ -363,6 +356,7 @@ static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)
{
int result;
void *kaddr = kmap(bvec->bv_page);
+
result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,
MSG_WAITALL);
kunmap(bvec->bv_page);
@@ -579,7 +573,27 @@ static int nbd_thread_send(void *data)
/* wait for something to do */
wait_event_interruptible(nbd->waiting_wq,
kthread_should_stop() ||
- !list_empty(&nbd->waiting_queue));
+ !list_empty(&nbd->waiting_queue) ||
+ atomic_read(&nbd->timedout));
+
+ if (atomic_read(&nbd->timedout)) {
+ mutex_lock(&nbd->sock_lock);
+ if (nbd->sock) {
+ struct request sreq;
+
+ blk_rq_init(NULL, &sreq);
+ sreq.cmd_type = REQ_TYPE_DRV_PRIV;
+ mutex_lock(&nbd->tx_lock);
+ nbd->disconnect = true;
+ nbd_send_req(nbd, &sreq);
+ mutex_unlock(&nbd->tx_lock);
+ dev_err(disk_to_dev(nbd->disk),
+ "Device Timeout occured.Shutting down"
+ " socket.");
+ }
+ mutex_unlock(&nbd->sock_lock);
+ sock_shutdown(nbd);
+ }

/* extract request */
if (list_empty(&nbd->waiting_queue))
@@ -592,7 +606,11 @@ static int nbd_thread_send(void *data)
spin_unlock_irq(&nbd->queue_lock);

/* handle request */
- nbd_handle_req(nbd, req);
+ if (atomic_read(&nbd->timedout)) {
+ req->errors++;
+ nbd_end_request(nbd, req);
+ } else
+ nbd_handle_req(nbd, req);
}

nbd->task_send = NULL;
@@ -601,8 +619,8 @@ static int nbd_thread_send(void *data)
}

/*
- * We always wait for result of write, for now. It would be nice to make it optional
- * in future
+ * We always wait for result of write, for now.
+ * It would be nice to make it optional in future
* if ((rq_data_dir(req) == WRITE) && (nbd->flags & NBD_WRITE_NOCHK))
* { printk( "Warning: Ignoring result!\n"); nbd_end_request( req ); }
*/
@@ -611,7 +629,7 @@ static void nbd_request_handler(struct request_queue *q)
__releases(q->queue_lock) __acquires(q->queue_lock)
{
struct request *req;
-
+
while ((req = blk_fetch_request(q)) != NULL) {
struct nbd_device *nbd;

@@ -647,7 +665,7 @@ static int nbd_set_socket(struct nbd_device *nbd, struct socket *sock)
{
int ret = 0;

- spin_lock_irq(&nbd->sock_lock);
+ mutex_lock(&nbd->sock_lock);

if (nbd->sock) {
ret = -EBUSY;
@@ -657,7 +675,7 @@ static int nbd_set_socket(struct nbd_device *nbd, struct socket *sock)
nbd->sock = sock;

out:
- spin_unlock_irq(&nbd->sock_lock);
+ mutex_unlock(&nbd->sock_lock);

return ret;
}
@@ -666,7 +684,7 @@ out:
static void nbd_reset(struct nbd_device *nbd)
{
nbd->disconnect = false;
- nbd->timedout = false;
+ atomic_set(&nbd->timedout, 0);
nbd->blksize = 1024;
nbd->bytesize = 0;
set_capacity(nbd->disk, 0);
@@ -729,7 +747,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd_send_req(nbd, &sreq);
return 0;
}
-
+
case NBD_CLEAR_SOCK:
sock_shutdown(nbd);
nbd_clear_que(nbd);
@@ -803,17 +821,15 @@ 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);
-
- mutex_lock(&nbd->tx_lock);
-
sock_shutdown(nbd);
+ mutex_lock(&nbd->tx_lock);
nbd_clear_que(nbd);
kill_bdev(bdev);
nbd_bdev_reset(bdev);

if (nbd->disconnect) /* user requested, ignore socket errors */
error = 0;
- if (nbd->timedout)
+ if (atomic_read(&nbd->timedout))
error = -ETIMEDOUT;

nbd_reset(nbd);
@@ -856,8 +872,7 @@ static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
return error;
}

-static const struct block_device_operations nbd_fops =
-{
+static const struct block_device_operations nbd_fops = {
.owner = THIS_MODULE,
.ioctl = nbd_ioctl,
.compat_ioctl = nbd_ioctl,
@@ -1075,7 +1090,7 @@ static int __init nbd_init(void)
nbd_dev[i].magic = NBD_MAGIC;
INIT_LIST_HEAD(&nbd_dev[i].waiting_queue);
spin_lock_init(&nbd_dev[i].queue_lock);
- spin_lock_init(&nbd_dev[i].sock_lock);
+ mutex_init(&nbd_dev[i].sock_lock);
INIT_LIST_HEAD(&nbd_dev[i].queue_head);
mutex_init(&nbd_dev[i].tx_lock);
init_timer(&nbd_dev[i].timeout_timer);
--
2.6.2
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