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From: Oliver Neukum <oneukum@suse.com>
To: Johan Hovold <johan@kernel.org>, Oliver Neukum <oneukum@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH 1/2] USB: cdc-acm: fix racy tty buffer accesses
Date: Thu, 30 Sep 2021 11:04:19 +0200	[thread overview]
Message-ID: <de1fd28a-0c7c-23ae-8b9d-83a682c169e3@suse.com> (raw)
In-Reply-To: <20210929090937.7410-2-johan@kernel.org>


On 29.09.21 11:09, Johan Hovold wrote:
> A recent change that started reporting break events to the line
> discipline caused the tty-buffer insertions to no longer be serialised
> by inserting events also from the completion handler for the interrupt
> endpoint.
>
> Completion calls for distinct endpoints are not guaranteed to be
> serialised. For example, in case a host-controller driver uses
> bottom-half completion, the interrupt and bulk-in completion handlers
> can end up running in parallel on two CPUs (high-and low-prio tasklets,
> respectively) thereby breaking the tty layer's single producer
> assumption.
>
> Fix this by holding the read lock also when inserting characters from
> the bulk endpoint.
>
> Fixes: 08dff274edda ("cdc-acm: fix BREAK rx code path adding necessary calls")
> Cc: stable@vger.kernel.org
> Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Oliver Neukum <oneukum@suse.com>


  reply	other threads:[~2021-09-30  9:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29  9:09 [PATCH 0/2] USB: cdc-acm: fix break reporting Johan Hovold
2021-09-29  9:09 ` [PATCH 1/2] USB: cdc-acm: fix racy tty buffer accesses Johan Hovold
2021-09-30  9:04   ` Oliver Neukum [this message]
2021-09-29  9:09 ` [PATCH 2/2] USB: cdc-acm: fix break reporting Johan Hovold
2021-09-30  9:05   ` Oliver Neukum

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