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From: James Hogan <jhogan@kernel.org>
To: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Cc: Ulf Hansson <ulf.hansson@linaro.org>,
	Paul Cercueil <paul@crapouillou.net>,
	linux-mmc@vger.kernel.org, linux-mips@linux-mips.org,
	Alex Smith <alex.smith@imgtec.com>
Subject: Re: [PATCH 09/14] mmc: jz4740: Fix race condition in IRQ mask update
Date: Fri, 9 Mar 2018 22:49:38 +0000	[thread overview]
Message-ID: <20180309224937.GI24558@saruman> (raw)
In-Reply-To: <20180309151219.18723-10-ezequiel@vanguardiasur.com.ar>

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On Fri, Mar 09, 2018 at 12:12:14PM -0300, Ezequiel Garcia wrote:
> From: Alex Smith <alex.smith@imgtec.com>
> 
> A spinlock is held while updating the internal copy of the IRQ mask,
> but not while writing it to the actual IMASK register. After the lock
> is released, an IRQ can occur before the IMASK register is written.
> If handling this IRQ causes the mask to be changed, when the handler
> returns back to the middle of the first mask update, a stale value
> will be written to the mask register.
> 
> If this causes an IRQ to become unmasked that cannot have its status
> cleared by writing a 1 to it in the IREG register, e.g. the SDIO IRQ,
> then we can end up stuck with the same IRQ repeatedly being fired but
> not handled. Normally the MMC IRQ handler attempts to clear any
> unexpected IRQs by writing IREG, but for those that cannot be cleared
> in this way then the IRQ will just repeatedly fire.
> 
> This was resulting in lockups after a while of using Wi-Fi on the
> CI20 (GitHub issue #19).
> 
> Resolve by holding the spinlock until after the IMASK register has
> been updated.
> 

Maybe have a Link tag instead of referencing "github issue #19", i.e.:
Link: https://github.com/MIPS/CI20_linux/issues/19

Since this fixes an older commit, it'd be worth adding:

Fixes: 61bfbdb85687 ("MMC: Add support for the controller on JZ4740 SoCs.")

> Signed-off-by: Alex Smith <alex.smith@imgtec.com>

... and presumably is worthy of backporting (the driver was introduced
in 2.6.36), i.e.:
Cc: stable@vger.kernel.org

Cheers
James

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  reply	other threads:[~2018-03-09 22:49 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-09 15:12 [PATCH 00/14] Enable SD/MMC on JZ4780 SoCs Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 01/14] mmc: jz4780: Order headers alphabetically Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 02/14] mmc: jz4740: Use dev_get_platdata Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 03/14] mmc: jz4740: Fix error exit path in driver's probe Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 04/14] mmc: jz4740: Reset the device requesting the interrupt Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 05/14] mmc: jz4740: Introduce devicetree probe Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 06/14] mmc: dt-bindings: add MMC support to JZ4740 SoC Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 07/14] mmc: jz4740: Set clock rate to mmc->f_max rather than JZ_MMC_CLK_RATE Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 08/14] mmc: jz4740: Add support for the JZ4780 Ezequiel Garcia
2018-03-09 17:51   ` [PATCH 08/14] mmc: jz4740: Add support for the JZ4780, Paul Cercueil
2018-03-09 22:31     ` your mail James Hogan
2018-03-09 22:31       ` James Hogan
2018-03-10 22:44     ` [PATCH 08/14] mmc: jz4740: Add support for the JZ4780 Ezequiel Garcia
2018-03-10 17:04   ` Mathieu Malaterre
2018-03-10 17:11   ` Mathieu Malaterre
2018-03-09 15:12 ` [PATCH 09/14] mmc: jz4740: Fix race condition in IRQ mask update Ezequiel Garcia
2018-03-09 22:49   ` James Hogan [this message]
2018-03-10 22:46     ` Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 10/14] mmc: jz4740: Use dma_request_chan() Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 11/14] MIPS: dts: jz4780: Add DMA controller node to the devicetree Ezequiel Garcia
2018-03-09 23:13   ` James Hogan
2018-03-11  1:31     ` Ezequiel Garcia
2018-03-09 15:12 ` [PATCH 12/14] MIPS: dts: jz4780: Add MMC " Ezequiel Garcia
2018-03-09 23:24   ` James Hogan
2018-03-09 15:12 ` [PATCH 13/14] MIPS: dts: ci20: Enable DMA and MMC in " Ezequiel Garcia
2018-03-09 23:39   ` James Hogan
2018-03-09 15:12 ` [PATCH 14/14] MIPS: configs: ci20: Enable DMA and MMC support Ezequiel Garcia
2018-03-09 23:30   ` James Hogan
2018-03-10 17:02 ` [PATCH 00/14] Enable SD/MMC on JZ4780 SoCs Mathieu Malaterre
2018-03-10 22:17   ` Ezequiel Garcia
2018-03-12 16:26     ` James Hogan
2018-03-12 17:15     ` Mathieu Malaterre

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