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Message-ID: <20110413060651.GA27823@mtj.dyndns.org>
Date: Wed, 13 Apr 2011 15:06:51 +0900
From: Tejun Heo <tj@...nel.org>
To: James Bottomley <James.Bottomley@...senPartnership.com>
Cc: Steven Whitehouse <swhiteho@...hat.com>,
linux-kernel@...r.kernel.org, Jens Axboe <jaxboe@...ionio.com>
Subject: Re: Strange block/scsi/workqueue issue
On Wed, Apr 13, 2011 at 02:18:46PM +0900, Tejun Heo wrote:
> Steven, can you be enticed to try the combination? I'll prep a
> combined patch and post it but please beware that I'm currently in a
> rather zombish state - sleep deprived, jet lagged and malfunctioning
> digestion - so the likelihood of doing something stupid is pretty
> high.
Does the following completely untested version work?
diff --git a/block/blk-core.c b/block/blk-core.c
index 90f22cc..bb27804 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -359,6 +359,14 @@ void blk_put_queue(struct request_queue *q)
*/
void blk_cleanup_queue(struct request_queue *q)
{
+ /* mark @q stopped and dead */
+ mutex_lock(&q->sysfs_lock);
+ spin_lock_irq(&q->queue_lock);
+ queue_flag_set(QUEUE_FLAG_STOPPED, q);
+ queue_flag_set(QUEUE_FLAG_DEAD, q);
+ spin_unlock_irq(&q->queue_lock);
+ mutex_unlock(&q->sysfs_lock);
+
/*
* We know we have process context here, so we can be a little
* cautious and ensure that pending block actions on this device
@@ -368,9 +376,6 @@ void blk_cleanup_queue(struct request_queue *q)
blk_sync_queue(q);
del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer);
- mutex_lock(&q->sysfs_lock);
- queue_flag_set_unlocked(QUEUE_FLAG_DEAD, q);
- mutex_unlock(&q->sysfs_lock);
if (q->elevator)
elevator_exit(q->elevator);
@@ -1456,7 +1461,7 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors)
* generic_make_request and the drivers it calls may use bi_next if this
* bio happens to be merged with someone else, and may change bi_dev and
* bi_sector for remaps as it sees fit. So the values of these fields
- * should NOT be depended on after the call to generic_make_request.
+ * should NOT be depended on after thes call to generic_make_request.
*/
static inline void __generic_make_request(struct bio *bio)
{
diff --git a/block/blk.h b/block/blk.h
index 6126346..4df474d 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -62,7 +62,8 @@ static inline struct request *__elv_next_request(struct request_queue *q)
return rq;
}
- if (!q->elevator->ops->elevator_dispatch_fn(q, 0))
+ if (test_bit(QUEUE_FLAG_DEAD, &q->queue_flags) ||
+ !q->elevator->ops->elevator_dispatch_fn(q, 0))
return NULL;
}
}
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 2aeb2e9..12ebcbc 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -70,6 +70,11 @@
#define CREATE_TRACE_POINTS
#include <trace/events/scsi.h>
+/*
+ * Utility multithreaded workqueue for SCSI.
+ */
+struct workqueue_struct *scsi_wq;
+
static void scsi_done(struct scsi_cmnd *cmd);
/*
@@ -1306,11 +1311,14 @@ MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
static int __init init_scsi(void)
{
- int error;
+ int error = -ENOMEM;
+ scsi_wq = alloc_workqueue("scsi", 0, 0);
+ if (!scsi_wq)
+ return error;
error = scsi_init_queue();
if (error)
- return error;
+ goto cleanup_wq;
error = scsi_init_procfs();
if (error)
goto cleanup_queue;
@@ -1342,6 +1350,8 @@ cleanup_procfs:
scsi_exit_procfs();
cleanup_queue:
scsi_exit_queue();
+cleanup_wq:
+ destroy_workqueue(scsi_wq);
printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
-error);
return error;
@@ -1356,6 +1366,7 @@ static void __exit exit_scsi(void)
scsi_exit_devinfo();
scsi_exit_procfs();
scsi_exit_queue();
+ destroy_workqueue(scsi_wq);
}
subsys_initcall(init_scsi);
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 087821f..4222b58 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -362,6 +362,16 @@ int scsi_is_target_device(const struct device *dev)
}
EXPORT_SYMBOL(scsi_is_target_device);
+static void scsi_target_reap_usercontext(struct work_struct *work)
+{
+ struct scsi_target *starget =
+ container_of(work, struct scsi_target, reap_work);
+
+ transport_remove_device(&starget->dev);
+ device_del(&starget->dev);
+ scsi_target_destroy(starget);
+}
+
static struct scsi_target *__scsi_find_target(struct device *parent,
int channel, uint id)
{
@@ -427,6 +437,7 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
starget->state = STARGET_CREATED;
starget->scsi_level = SCSI_2;
starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
+ INIT_WORK(&starget->reap_work, scsi_target_reap_usercontext);
retry:
spin_lock_irqsave(shost->host_lock, flags);
@@ -462,21 +473,11 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
}
/* Unfortunately, we found a dying target; need to
* wait until it's dead before we can get a new one */
+ flush_work(&found_target->reap_work);
put_device(&found_target->dev);
- flush_scheduled_work();
goto retry;
}
-static void scsi_target_reap_usercontext(struct work_struct *work)
-{
- struct scsi_target *starget =
- container_of(work, struct scsi_target, ew.work);
-
- transport_remove_device(&starget->dev);
- device_del(&starget->dev);
- scsi_target_destroy(starget);
-}
-
/**
* scsi_target_reap - check to see if target is in use and destroy if not
* @starget: target to be checked
@@ -507,8 +508,7 @@ void scsi_target_reap(struct scsi_target *starget)
if (state == STARGET_CREATED)
scsi_target_destroy(starget);
else
- execute_in_process_context(scsi_target_reap_usercontext,
- &starget->ew);
+ queue_work(scsi_wq, &starget->reap_work);
}
/**
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index e44ff64..e030091 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -300,7 +300,7 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
struct list_head *this, *tmp;
unsigned long flags;
- sdev = container_of(work, struct scsi_device, ew.work);
+ sdev = container_of(work, struct scsi_device, release_work);
parent = sdev->sdev_gendev.parent;
starget = to_scsi_target(parent);
@@ -323,7 +323,6 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
}
if (sdev->request_queue) {
- sdev->request_queue->queuedata = NULL;
/* user context needed to free queue */
scsi_free_queue(sdev->request_queue);
/* temporary expedient, try to catch use of queue lock
@@ -343,8 +342,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
static void scsi_device_dev_release(struct device *dev)
{
struct scsi_device *sdp = to_scsi_device(dev);
- execute_in_process_context(scsi_device_dev_release_usercontext,
- &sdp->ew);
+
+ queue_work(scsi_wq, &sdp->release_work);
}
static struct class sdev_class = {
@@ -937,6 +936,7 @@ void __scsi_remove_device(struct scsi_device *sdev)
if (sdev->host->hostt->slave_destroy)
sdev->host->hostt->slave_destroy(sdev);
transport_destroy_device(dev);
+ sdev->request_queue->queuedata = NULL;
put_device(dev);
}
@@ -1069,6 +1069,8 @@ void scsi_sysfs_device_initialize(struct scsi_device *sdev)
dev_set_name(&sdev->sdev_dev, "%d:%d:%d:%d",
sdev->host->host_no, sdev->channel, sdev->id, sdev->lun);
sdev->scsi_level = starget->scsi_level;
+ INIT_WORK(&sdev->release_work, scsi_device_dev_release_usercontext);
+
transport_setup_device(&sdev->sdev_gendev);
spin_lock_irqsave(shost->host_lock, flags);
list_add_tail(&sdev->same_target_siblings, &starget->devices);
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 2d3ec50..1d11750 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -168,7 +168,7 @@ struct scsi_device {
struct device sdev_gendev,
sdev_dev;
- struct execute_work ew; /* used to get process context on put */
+ struct work_struct release_work; /* for process context on put */
struct scsi_dh_data *scsi_dh_data;
enum scsi_device_state sdev_state;
@@ -259,7 +259,7 @@ struct scsi_target {
#define SCSI_DEFAULT_TARGET_BLOCKED 3
char scsi_level;
- struct execute_work ew;
+ struct work_struct reap_work;
enum scsi_target_state state;
void *hostdata; /* available to low-level driver */
unsigned long starget_data[0]; /* for the transport */
@@ -277,6 +277,8 @@ static inline struct scsi_target *scsi_target(struct scsi_device *sdev)
#define starget_printk(prefix, starget, fmt, a...) \
dev_printk(prefix, &(starget)->dev, fmt, ##a)
+extern struct workqueue_struct *scsi_wq;
+
extern struct scsi_device *__scsi_add_device(struct Scsi_Host *,
uint, uint, uint, void *hostdata);
extern int scsi_add_device(struct Scsi_Host *host, uint channel,
--
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