From: Alan Stern <stern@rowland.harvard.edu>
To: Michal Nazarewicz <mina86@mina86.com>
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>,
<linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>,
<stable@vger.kernel.org>
Subject: Re: [PATCHv2] usb: f_mass_storage: test whether thread is running before starting another
Date: Fri, 8 Apr 2016 11:19:45 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1604081119260.2069-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <1460103851-16102-1-git-send-email-mina86@mina86.com>
On Fri, 8 Apr 2016, Michal Nazarewicz wrote:
> When binding the function to usb_configuration, check whether the thread
> is running before starting another one. Without that, when function
> instance is added to multiple configurations, fsg_bing starts multiple
> threads with all but the latest one being forgotten by the driver. This
> leads to obvious thread leaks, possible lockups when trying to halt the
> machine and possible more issues.
>
> This fixes issues with legacy/multi¹ gadget as well as configfs gadgets
> when mass_storage function is added to multiple configurations.
>
> This change also simplifies API since the legacy gadgets no longer need
> to worry about starting the thread by themselves (which was where bug
> in legacy/multi was in the first place).
>
> N.B., this patch doesn’t address adding single mass_storage function
> instance to a single configuration twice. Thankfully, there’s no
> legitimate reason for such setup plus, if I’m not mistaken, configfs
> gadget doesn’t even allow it to be expressed.
>
> ¹ I have no example failure though. Conclusion that legacy/multi has
> a bug is based purely on me reading the code.
>
> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
> Tested-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
> Cc: Alan Stern <stern@rowland.harvard.edu>
> Cc: stable@vger.kernel.org
Acked-by: Alan Stern <stern@rowland.harvard.edu>
prev parent reply other threads:[~2016-04-08 15:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-08 8:24 [PATCHv2] usb: f_mass_storage: test whether thread is running before starting another Michal Nazarewicz
2016-04-08 8:27 ` Michal Nazarewicz
2016-04-08 15:19 ` Alan Stern [this message]
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