From: "Jon Medhurst (Tixy)" <jon.medhurst@linaro.org>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: linux-mmc@vger.kernel.org, Lee Jones <lee.jones@linaro.org>,
Ulf Hansson <ulf.hansson@stericsson.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] mmc: mmci: Do not release spinlock in request_end
Date: Thu, 13 Oct 2011 16:59:52 +0100 [thread overview]
Message-ID: <1318521592.2090.16.camel@linaro1> (raw)
In-Reply-To: <20111013142914.GZ21648@n2100.arm.linux.org.uk>
On Thu, 2011-10-13 at 15:29 +0100, Russell King - ARM Linux wrote:
> On Tue, Oct 11, 2011 at 04:06:41PM +0200, Ulf Hansson wrote:
> > The patch "mmc: core: move ->request() call from atomic context",
> > is the reason to why this change is possible. This simplifies the
> > error handling code execution path quite a lot and potentially also
> > fixes some error handling hang problems.
> >
> > Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
>
> This doesn't look right:
>
> void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
> {
> if (err && cmd->retries) {
> host->ops->request(host, mrq);
>
> So, not dropping the spinlock results in calling the request function
> with the spinlock held - and as the request function then goes on to
> lock the spinlock, we will deadlock.
Indeed, deadlock behaviour at this point is what I see with this patch
on a Versatile Express board running 3.0-rc9.
--
Tixy
WARNING: multiple messages have this Message-ID (diff)
From: jon.medhurst@linaro.org (Jon Medhurst (Tixy))
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] mmc: mmci: Do not release spinlock in request_end
Date: Thu, 13 Oct 2011 16:59:52 +0100 [thread overview]
Message-ID: <1318521592.2090.16.camel@linaro1> (raw)
In-Reply-To: <20111013142914.GZ21648@n2100.arm.linux.org.uk>
On Thu, 2011-10-13 at 15:29 +0100, Russell King - ARM Linux wrote:
> On Tue, Oct 11, 2011 at 04:06:41PM +0200, Ulf Hansson wrote:
> > The patch "mmc: core: move ->request() call from atomic context",
> > is the reason to why this change is possible. This simplifies the
> > error handling code execution path quite a lot and potentially also
> > fixes some error handling hang problems.
> >
> > Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
>
> This doesn't look right:
>
> void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
> {
> if (err && cmd->retries) {
> host->ops->request(host, mrq);
>
> So, not dropping the spinlock results in calling the request function
> with the spinlock held - and as the request function then goes on to
> lock the spinlock, we will deadlock.
Indeed, deadlock behaviour at this point is what I see with this patch
on a Versatile Express board running 3.0-rc9.
--
Tixy
next prev parent reply other threads:[~2011-10-13 15:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-11 14:06 [PATCH] mmc: mmci: Do not release spinlock in request_end Ulf Hansson
2011-10-11 14:06 ` Ulf Hansson
2011-10-12 9:41 ` Linus Walleij
2011-10-12 9:41 ` Linus Walleij
2011-10-12 10:33 ` Adrian Hunter
2011-10-12 10:33 ` Adrian Hunter
2011-10-13 14:29 ` Russell King - ARM Linux
2011-10-13 14:29 ` Russell King - ARM Linux
2011-10-13 15:59 ` Jon Medhurst (Tixy) [this message]
2011-10-13 15:59 ` Jon Medhurst (Tixy)
2011-10-14 7:37 ` Ulf Hansson
2011-10-14 7:37 ` Ulf Hansson
2011-10-14 7:42 ` Russell King - ARM Linux
2011-10-14 7:42 ` Russell King - ARM Linux
2011-10-14 7:51 ` Ulf Hansson
2011-10-14 7:51 ` Ulf Hansson
2011-10-14 8:03 ` Russell King - ARM Linux
2011-10-14 8:03 ` Russell King - ARM Linux
2011-10-14 8:22 ` Ulf Hansson
2011-10-14 8:22 ` Ulf Hansson
2011-10-16 20:34 ` Linus Walleij
2011-10-16 20:34 ` Linus Walleij
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