From: Mike Turquette <mturquette@linaro.org>
To: Tomasz Figa <t.figa@samsung.com>
Cc: Daniel Drake <drake@endlessm.com>,
linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
linux-mmc@vger.kernel.org, Ben Dooks <ben-linux@fluff.org>,
Tomasz Figa <tomasz.figa@gmail.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
Chris Ball <chris@printf.net>
Subject: Re: sdhci_s3c_consider_clock scheduling while atomic - clk_round_rate
Date: Mon, 18 Aug 2014 08:46:25 -0700 [thread overview]
Message-ID: <CAPtuhTiTTLqd1UGoVAnRa0EUHqbGTHm+=Avb=aS8sECOjOqAVQ@mail.gmail.com> (raw)
In-Reply-To: <53A99EB5.6010907@samsung.com>
On Tue, Jun 24, 2014 at 8:52 AM, Tomasz Figa <t.figa@samsung.com> wrote:
> Hi Daniel,
>
> [adding Ulf, Chris and Mike to the discussion]
>
> On 24.06.2014 11:48, Daniel Drake wrote:
>> sdhci_s3c_set_clock is called from sdhci_do_set_ios with interrupts
>> disabled, and this calls into sdhci_s3c_consider_clock().
>>
>> The patch "mmc: sdhci-s3c: Cache bus clock rates" addressed some
>> scheduling while atomic in this function, but there are more issues
>> here, seen while testing 3.16-rc2 on exynos4412:
>>
>> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:103
>> in_atomic(): 1, irqs_disabled(): 128, pid: 75, name: mmcqd/0
>> Preemption disabled at:[< (null)>] (null)
>>
>> CPU: 0 PID: 75 Comm: mmcqd/0 Not tainted 3.16.0-rc2-00028-ge9fe7eb-dirty #77
>> [<c0016140>] (unwind_backtrace) from [<c0011e14>] (show_stack+0x10/0x14)
>> [<c0011e14>] (show_stack) from [<c05ce8a8>] (dump_stack+0x84/0xc4)
>> [<c05ce8a8>] (dump_stack) from [<c05d2de0>] (mutex_lock+0x1c/0x3c)
>> [<c05d2de0>] (mutex_lock) from [<c046214c>] (clk_prepare_lock+0x6c/0xf4)
>> [<c046214c>] (clk_prepare_lock) from [<c04625ac>] (clk_round_rate+0x10/0x2c)
>> [<c04625ac>] (clk_round_rate) from [<c0447628>] (sdhci_s3c_set_clock+0x4c/0x1e8)
>> [<c0447628>] (sdhci_s3c_set_clock) from [<c0447818>]
>> (sdhci_cmu_set_clock+0x54/0x140)
>> [<c0447818>] (sdhci_cmu_set_clock) from [<c0443a38>]
>> (sdhci_do_set_ios+0x138/0x58c)
>> [<c0443a38>] (sdhci_do_set_ios) from [<c0443864>] (sdhci_set_ios+0x28/0x34)
>>
>> clk_round_rate cannot be called here because it takes a mutex.
>>
>> sdhci_s3c_set_clock() also calls into clk_prepare_enable() which looks
>> like it could trigger this problem too.
Perhaps this clk_prepare_enable could be converted simply to
clk_enable? Of course a call to clk_prepare call would still be
required before entering into the section where clk_enable is called.
Regards,
Mike
>
> Apparently this is related to generic sdhci code calling .set_clock()
> under spin_lock_irqsave(). For reference, see sdhci_do_set_ios() and
> sdhci_tasklet_finish().
>
> Chris, Ulf, any suggestions?
>
> Best regards,
> Tomasz
prev parent reply other threads:[~2014-08-18 15:46 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-24 9:48 sdhci_s3c_consider_clock scheduling while atomic - clk_round_rate Daniel Drake
2014-06-24 15:52 ` Tomasz Figa
2014-07-15 6:33 ` Jaehoon Chung
2014-08-13 9:10 ` Ulf Hansson
2014-08-18 15:46 ` Mike Turquette [this message]
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