[PATCH 2/2] mmc: mxs-mmc: fix deadlock caused by recursion loop

[Chris Ball]

Hi,

On Tue, Jul 17 2012, Lauri Hintsala wrote:
> Release the lock before mmc_signal_sdio_irq is called by
> mxs_mmc_enable_sdio_irq.
>
> Backtrace:
> [   65.470000] =============================================
> [   65.470000] [ INFO: possible recursive locking detected ]
> [   65.470000] 3.5.0-rc5 #2 Not tainted
> [   65.470000] ---------------------------------------------
> [   65.470000] ksdioirqd/mmc0/73 is trying to acquire lock:
> [   65.470000]  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
> [   65.470000]
> [   65.470000] but task is already holding lock:
> [   65.470000]  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
> [   65.470000]
> [   65.470000] other info that might help us debug this:
> [   65.470000]  Possible unsafe locking scenario:
> [   65.470000]
> [   65.470000]        CPU0
> [   65.470000]        ----
> [   65.470000]   lock(&(&host->lock)->rlock#2);
> [   65.470000]   lock(&(&host->lock)->rlock#2);
> [   65.470000]
> [   65.470000]  *** DEADLOCK ***
> [   65.470000]
> [   65.470000]  May be due to missing lock nesting notation
> [   65.470000]
> [   65.470000] 1 lock held by ksdioirqd/mmc0/73:
> [   65.470000]  #0:  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
> [   65.470000]
> [   65.470000] stack backtrace:
> [   65.470000] [<c0014990>] (unwind_backtrace+0x0/0xf4) from [<c005ccb8>] (__lock_acquire+0x14f8/0x1b98)
> [   65.470000] [<c005ccb8>] (__lock_acquire+0x14f8/0x1b98) from [<c005d3f8>] (lock_acquire+0xa0/0x108)
> [   65.470000] [<c005d3f8>] (lock_acquire+0xa0/0x108) from [<c02f671c>] (_raw_spin_lock_irqsave+0x48/0x5c)
> [   65.470000] [<c02f671c>] (_raw_spin_lock_irqsave+0x48/0x5c) from [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc])
> [   65.470000] [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]) from [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc])
> [   65.470000] [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc]) from [<c0219b38>] (sdio_irq_thread+0x1bc/0x274)
> [   65.470000] [<c0219b38>] (sdio_irq_thread+0x1bc/0x274) from [<c003c324>] (kthread+0x8c/0x98)
> [   65.470000] [<c003c324>] (kthread+0x8c/0x98) from [<c00101ac>] (kernel_thread_exit+0x0/0x8)
> [   65.470000] BUG: spinlock lockup suspected on CPU#0, ksdioirqd/mmc0/73
> [   65.470000]  lock: 0xc3358724, .magic: dead4ead, .owner: ksdioirqd/mmc0/73, .owner_cpu: 0
> [   65.470000] [<c0014990>] (unwind_backtrace+0x0/0xf4) from [<c01b46b0>] (do_raw_spin_lock+0x100/0x144)
> [   65.470000] [<c01b46b0>] (do_raw_spin_lock+0x100/0x144) from [<c02f6724>] (_raw_spin_lock_irqsave+0x50/0x5c)
> [   65.470000] [<c02f6724>] (_raw_spin_lock_irqsave+0x50/0x5c) from [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc])
> [   65.470000] [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]) from [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc])
> [   65.470000] [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc]) from [<c0219b38>] (sdio_irq_thread+0x1bc/0x274)
> [   65.470000] [<c0219b38>] (sdio_irq_thread+0x1bc/0x274) from [<c003c324>] (kthread+0x8c/0x98)
> [   65.470000] [<c003c324>] (kthread+0x8c/0x98) from [<c00101ac>] (kernel_thread_exit+0x0/0x8)
>
> Reported-by: Attila Kinali <attila at kinali.ch>
> Signed-off-by: Lauri Hintsala <lauri.hintsala at bluegiga.com>
> Acked-by: Shawn Guo <shawn.guo at linaro.org>
> ---
>  drivers/mmc/host/mxs-mmc.c |   10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
> index 20a0550..e1fd2c8 100644
> --- a/drivers/mmc/host/mxs-mmc.c
> +++ b/drivers/mmc/host/mxs-mmc.c
> @@ -637,11 +637,6 @@ static void mxs_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>  		       host->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);
>  		writel(BM_SSP_CTRL1_SDIO_IRQ_EN,
>  		       host->base + HW_SSP_CTRL1(host) + STMP_OFFSET_REG_SET);
> -
> -		if (readl(host->base + HW_SSP_STATUS(host)) &
> -				BM_SSP_STATUS_SDIO_IRQ)
> -			mmc_signal_sdio_irq(host->mmc);
> -
>  	} else {
>  		writel(BM_SSP_CTRL0_SDIO_IRQ_CHECK,
>  		       host->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_CLR);
> @@ -650,6 +645,11 @@ static void mxs_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>  	}
>  
>  	spin_unlock_irqrestore(&host->lock, flags);
> +
> +	if (enable && readl(host->base + HW_SSP_STATUS(host)) &
> +			BM_SSP_STATUS_SDIO_IRQ)
> +		mmc_signal_sdio_irq(host->mmc);
> +
>  }
>  
>  static const struct mmc_host_ops mxs_mmc_ops = {

Thanks, pushed to mmc-next for 3.6 with a stable@ tag.

- Chris.
-- 
Chris Ball   <cjb at laptop.org>   <http://printf.net/>
One Laptop Per Child