linux-kernel - Re: [PATCH] mmc: sdhci: disable irq in sdhci host suspend ranther than free this irq

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Date:	Thu, 28 Jan 2016 17:27:46 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Ulf Hansson <ulf.hansson@...aro.org>
cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Haibo Chen <haibo.chen@....com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jon Hunter <jonathanh@...dia.com>
Subject: Re: [PATCH] mmc: sdhci: disable irq in sdhci host suspend ranther
 than free this irq

On Thu, 28 Jan 2016, Thomas Gleixner wrote:
> On Thu, 28 Jan 2016, Ulf Hansson wrote:
> > Therefore, the only way we currently can make sure to don't get the
> > IRQ is to free and later re-request it. Now, apparently that has
> > issues when using threaded IRQ handlers.
> 
> What's the issue?

Ah, you mean that one:

> Currently sdhci driver free irq in host suspend, and call
> request_threaded_irq() in host resume. But during host resume,
> Ctrl+C can impact sdhci host resume, see the error log:

> CPU1 is up
> PM: noirq resume of devices complete after 0.637 msecs imx-sdma 30bd0000.sdma: loaded firmware 4.1
> PM: early resume of devices complete after 0.774 msecs
> dpm_run_callback(): platform_pm_resume+0x0/0x44 returns -4
> PM: Device 30b40000.usdhc failed to resume: error -4
> dpm_run_callback(): platform_pm_resume+0x0/0x44 returns -4
> PM: Device 30b50000.usdhc failed to resume: error -4
> dpm_run_callback(): platform_pm_resume+0x0/0x44 returns -4
> PM: Device 30b60000.usdhc failed to resume: error -4 fec 30be0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: Timeout waiting for hardware interrupt.
> mmc0: error -110 during resume (card was removed?)
> mmc2: Timeout waiting for hardware interrupt.
> mmc2: Timeout waiting for hardware interrupt.
> mmc2: error -110 during resume (card was removed?)

In request_threaded_irq-> __setup_irq-> kthread_create
->kthread_create_on_node, the comment shows that SIGKILLed will
impact the kthread create, and return -EINTR.

And how should that thread be SIGKILLed? Hitting Ctrl+C on the console does
not affect any kernel internal thread. Hitting Ctrl+C affects solely the
process which is running on that console.

And if it would, then that would be a completely different, serious bug which
needs to be fixed.

How was verified, that the thread was not created and that the creation failed
due to a SIGKILL?

Thanks,

	tglx