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UAS: fix deadlock in error handling and PM flushing work

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A SCSI error handler and block runtime PM must not allocate
memory with GFP_KERNEL. Furthermore they must not wait for
tasks allocating memory with GFP_KERNEL.
That means that they cannot share a workqueue with arbitrary tasks.

Fix this for UAS using a private workqueue.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Fixes: f9dc024a2d ("uas: pre_reset and suspend: Fix a few races")
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200415141750.811-2-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oliver Neukum 2020-04-15 16:17:50 +02:00 committed by Greg Kroah-Hartman
parent 5963dec98d
commit f6cc6093a7
1 changed files with 40 additions and 3 deletions
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43
drivers/usb/storage/uas.c
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@ -81,6 +81,19 @@ static void uas_free_streams(struct uas_dev_info *devinfo);
static void uas_log_cmd_state(struct scsi_cmnd *cmnd, const char *prefix,
int status);
/*
* This driver needs its own workqueue, as we need to control memory allocation.
*
* In the course of error handling and power management uas_wait_for_pending_cmnds()
* needs to flush pending work items. In these contexts we cannot allocate memory
* by doing block IO as we would deadlock. For the same reason we cannot wait
* for anything allocating memory not heeding these constraints.
*
* So we have to control all work items that can be on the workqueue we flush.
* Hence we cannot share a queue and need our own.
*/
static struct workqueue_struct *workqueue;
static void uas_do_work(struct work_struct *work)
{
struct uas_dev_info *devinfo =
@ -109,7 +122,7 @@ static void uas_do_work(struct work_struct *work)
if (!err)
cmdinfo->state &= ~IS_IN_WORK_LIST;
else
schedule_work(&devinfo->work);
queue_work(workqueue, &devinfo->work);
}
out:
spin_unlock_irqrestore(&devinfo->lock, flags);
@ -134,7 +147,7 @@ static void uas_add_work(struct uas_cmd_info *cmdinfo)
lockdep_assert_held(&devinfo->lock);
cmdinfo->state |= IS_IN_WORK_LIST;
schedule_work(&devinfo->work);
queue_work(workqueue, &devinfo->work);
}
static void uas_zap_pending(struct uas_dev_info *devinfo, int result)
@ -1229,7 +1242,31 @@ static struct usb_driver uas_driver = {
.id_table = uas_usb_ids,
};
module_usb_driver(uas_driver);
static int __init uas_init(void)
{
int rv;
workqueue = alloc_workqueue("uas", WQ_MEM_RECLAIM, 0);
if (!workqueue)
return -ENOMEM;
rv = usb_register(&uas_driver);
if (rv) {
destroy_workqueue(workqueue);
return -ENOMEM;
}
return 0;
}
static void __exit uas_exit(void)
{
usb_deregister(&uas_driver);
destroy_workqueue(workqueue);
}
module_init(uas_init);
module_exit(uas_exit);
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS(USB_STORAGE);