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authorOliver Neukum <oneukum@suse.com>2020-04-15 16:17:50 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-29 16:31:34 +0200
commite076da135b81df39e95a10a2360eb49c868ae68f (patch)
tree586970f94cffed8c3fdff45fdce24746b59f1693
parent9ca6a4d89872d6c1abb41ded2aa139b703d67ab2 (diff)
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UAS: fix deadlock in error handling and PM flushing work
commit f6cc6093a729ede1ff5658b493237c42b82ba107 upstream. 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: f9dc024a2da1f ("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>
-rw-r--r--drivers/usb/storage/uas.c43
1 files changed, 40 insertions, 3 deletions
diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c
index f7778cf6e436..27d8b4b6ff59 100644
--- a/drivers/usb/storage/uas.c
+++ b/drivers/usb/storage/uas.c
@@ -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)
@@ -1236,7 +1249,31 @@ 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_AUTHOR(