[PATCH] mmc: sdhci-pxav3: fix race between runtime pm and irq

From: Jisheng Zhang
Date: Wed Jan 21 2015 - 07:48:32 EST


This patch is to fix a race condition that may cause an unhandled irq,
which results in big sdhci interrupt numbers and endless "mmc1: got irq
while runtime suspended" msgs before v3.15.

Consider following scenario:

CPU0 CPU1
sdhci_pxav3_runtime_suspend()
spin_lock_irqsave(&host->lock, flags);
sdhci_irq()
spining on the &host->lock
host->runtime_suspended = true;
spin_unlock_irqrestore(&host->lock, flags);
get the &host->lock
runtime_suspended is true now
return IRQ_NONE;

Fix this race by using the core sdhci.c supplied sdhci_runtime_suspend_host()
in runtime suspend hook which will disable card interrupts. We also use the
sdhci_runtime_resume_host() in the runtime resume hook accordingly.

Signed-off-by: Jisheng Zhang <jszhang@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.9+
---
drivers/mmc/host/sdhci-pxav3.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pxav3.c b/drivers/mmc/host/sdhci-pxav3.c
index 4de39fb..6975c51 100644
--- a/drivers/mmc/host/sdhci-pxav3.c
+++ b/drivers/mmc/host/sdhci-pxav3.c
@@ -460,17 +460,15 @@ static int sdhci_pxav3_runtime_suspend(struct device *dev)
struct sdhci_host *host = dev_get_drvdata(dev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_pxa *pxa = pltfm_host->priv;
- unsigned long flags;
+ int ret;

- spin_lock_irqsave(&host->lock, flags);
- host->runtime_suspended = true;
- spin_unlock_irqrestore(&host->lock, flags);
+ ret = sdhci_runtime_suspend_host(host);

clk_disable_unprepare(pxa->clk_io);
if (!IS_ERR(pxa->clk_core))
clk_disable_unprepare(pxa->clk_core);

- return 0;
+ return ret;
}

static int sdhci_pxav3_runtime_resume(struct device *dev)
@@ -478,17 +476,12 @@ static int sdhci_pxav3_runtime_resume(struct device *dev)
struct sdhci_host *host = dev_get_drvdata(dev);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_pxa *pxa = pltfm_host->priv;
- unsigned long flags;

clk_prepare_enable(pxa->clk_io);
if (!IS_ERR(pxa->clk_core))
clk_prepare_enable(pxa->clk_core);

- spin_lock_irqsave(&host->lock, flags);
- host->runtime_suspended = false;
- spin_unlock_irqrestore(&host->lock, flags);
-
- return 0;
+ return sdhci_runtime_resume_host(host);
}
#endif

--
2.1.4

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