patch "cdc-acm: close race betrween suspend() and acm_softint" added to usb-linus

This is a note to let you know that I've just added the patch titled

cdc-acm: close race betrween suspend() and acm_softint

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 0afccd7601514c4b83d8cc58c740089cc447051d Mon Sep 17 00:00:00 2001
From: Oliver Neukum <[email protected]>
Date: Wed, 15 Apr 2020 17:13:57 +0200
Subject: cdc-acm: close race betrween suspend() and acm_softint

Suspend increments a counter, then kills the URBs, then kills the scheduled work. The scheduled work, however, may reschedule the URBs. Fix this by having the work check the counter.

---
 drivers/usb/class/cdc-acm.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

index 84d6f7df09a4..4ef68e6671aa 100644
@@ -557,14 +557,14 @@ static void acm_softint(struct work_struct *work)
 	struct acm *acm = container_of(work, struct acm, work);
 
 	if (test_bit(EVENT_RX_STALL, &acm->flags)) {
-		if (!(usb_autopm_get_interface(acm->data))) {
+		smp_mb(); /* against acm_suspend() */
+		if (!acm->susp_count) {
 			for (i = 0; i < acm->rx_buflimit; i++)
 				usb_kill_urb(acm->read_urbs[i]);
 			usb_clear_halt(acm->dev, acm->in);
 			acm_submit_read_urbs(acm, GFP_KERNEL);
-			usb_autopm_put_interface(acm->data);
+			clear_bit(EVENT_RX_STALL, &acm->flags);
 		}
-		clear_bit(EVENT_RX_STALL, &acm->flags);
 	}
 
 	if (test_and_clear_bit(EVENT_TTY_WAKEUP, &acm->flags))

2.26.1