From: Tony Lindgren <tony@atomide.com>
To: Paul Cercueil <paul@crapouillou.net>
Cc: Bin Liu <b-liu@ti.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Johan Hovold <johan@kernel.org>,
od@zcrc.me, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] usb: musb: Fix runtime PM race in musb_queue_resume_work
Date: Mon, 17 Aug 2020 13:59:26 +0300 [thread overview]
Message-ID: <20200817105926.GF2994@atomide.com> (raw)
In-Reply-To: <20200809125359.31025-1-paul@crapouillou.net>
* Paul Cercueil <paul@crapouillou.net> [200809 12:54]:
> musb_queue_resume_work() would call the provided callback if the runtime
> PM status was 'active'. Otherwise, it would enqueue the request if the
> hardware was still suspended (musb->is_runtime_suspended is true).
>
> This causes a race with the runtime PM handlers, as it is possible to be
> in the case where the runtime PM status is not yet 'active', but the
> hardware has been awaken (PM resume function has been called).
>
> When hitting the race, the resume work was not enqueued, which probably
> triggered other bugs further down the stack. For instance, a telnet
> connection on Ingenic SoCs would result in a 50/50 chance of a
> segmentation fault somewhere in the musb code.
>
> Rework the code so that either we call the callback directly if
> (musb->is_runtime_suspended == 0), or enqueue the query otherwise.
Yes we should use is_runtime_suspended, thanks for fixing it.
Things still work for me so:
Reviewed-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
next prev parent reply other threads:[~2020-08-17 10:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-09 12:53 [PATCH] usb: musb: Fix runtime PM race in musb_queue_resume_work Paul Cercueil
2020-08-17 10:59 ` Tony Lindgren [this message]
2020-09-28 0:52 ` Paul Cercueil
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