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* [PATCH] CDC-ACM: fix poison/unpoison imbalance
@ 2021-04-21  7:45 Oliver Neukum
  2021-04-22 11:35 ` Stefan Agner
  0 siblings, 1 reply; 2+ messages in thread
From: Oliver Neukum @ 2021-04-21  7:45 UTC (permalink / raw)
  To: gregKH, linux-usb; +Cc: Oliver Neukum

suspend() does its poisoning conditionally, resume() does it
unconditionally. On a device with combined interfaces this
will balance, on a device with two interfaces the counter will
go negative and resubmission will fail.

Both actions need to be done conditionally.

Fixes: 6069e3e927c8f ("USB: cdc-acm: untangle a circular dependency between callback and softint")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/class/cdc-acm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 3fda1ec961d7..f5886c512fec 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1634,12 +1634,13 @@ static int acm_resume(struct usb_interface *intf)
 	struct urb *urb;
 	int rv = 0;
 
-	acm_unpoison_urbs(acm);
 	spin_lock_irq(&acm->write_lock);
 
 	if (--acm->susp_count)
 		goto out;
 
+	acm_unpoison_urbs(acm);
+
 	if (tty_port_initialized(&acm->port)) {
 		rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);
 
-- 
2.26.2


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] CDC-ACM: fix poison/unpoison imbalance
  2021-04-21  7:45 [PATCH] CDC-ACM: fix poison/unpoison imbalance Oliver Neukum
@ 2021-04-22 11:35 ` Stefan Agner
  0 siblings, 0 replies; 2+ messages in thread
From: Stefan Agner @ 2021-04-22 11:35 UTC (permalink / raw)
  To: Oliver Neukum; +Cc: gregKH, linux-usb

On 2021-04-21 09:45, Oliver Neukum wrote:
> suspend() does its poisoning conditionally, resume() does it
> unconditionally. On a device with combined interfaces this
> will balance, on a device with two interfaces the counter will
> go negative and resubmission will fail.
> 
> Both actions need to be done conditionally.

FWIW, this relates to the issue reported on the kernel bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=212725

Thanks for addressing this!

> 
> Fixes: 6069e3e927c8f ("USB: cdc-acm: untangle a circular dependency
> between callback and softint")
> Signed-off-by: Oliver Neukum <oneukum@suse.com>

Tested-by: Stefan Agner <stefan@agner.ch>

--
Stefan

> ---
>  drivers/usb/class/cdc-acm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
> index 3fda1ec961d7..f5886c512fec 100644
> --- a/drivers/usb/class/cdc-acm.c
> +++ b/drivers/usb/class/cdc-acm.c
> @@ -1634,12 +1634,13 @@ static int acm_resume(struct usb_interface *intf)
>  	struct urb *urb;
>  	int rv = 0;
>  
> -	acm_unpoison_urbs(acm);
>  	spin_lock_irq(&acm->write_lock);
>  
>  	if (--acm->susp_count)
>  		goto out;
>  
> +	acm_unpoison_urbs(acm);
> +
>  	if (tty_port_initialized(&acm->port)) {
>  		rv = usb_submit_urb(acm->ctrlurb, GFP_ATOMIC);

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2021-04-22 11:42 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2021-04-21  7:45 [PATCH] CDC-ACM: fix poison/unpoison imbalance Oliver Neukum
2021-04-22 11:35 ` Stefan Agner

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