>From 5cfcd26b872719089dd714b5b1047d4d6e985889 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@xxxxxxx>
Date: Tue, 20 Jan 2015 15:28:53 +0100
Subject: [PATCH] cdc-wdm: fix deadlock in scheduled work
The scheduled work can deadlock in the error
handling case.
kmalloc with GFP_KERNEL in the work
VM layer decides to page to storage interface
task blocks waiting for completion of IO
SCSI layer sees an error
SCSI error handling starts
SCSI layer requests a bus reset
USB layer calls pre_reset() of cdc-wdm
wdm_pre_reset() calls cancel_work_sync()
cancel_work_sync() waits for work to finish
DEADLOCK
Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
---
drivers/usb/class/cdc-wdm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index e24bad6..93dd8b8 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -738,7 +738,7 @@ static void wdm_rxwork(struct work_struct *work)
responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
spin_unlock_irqrestore(&desc->iuspin, flags);
if (!responding)
- rv = usb_submit_urb(desc->response, GFP_KERNEL);
+ rv = usb_submit_urb(desc->response, GFP_NOIO);
if (rv < 0 && rv != -EPERM) {
spin_lock_irqsave(&desc->iuspin, flags);
clear_bit(WDM_RESPONDING, &desc->flags);
--
1.8.4.5
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