linux-kernel - [PATCH 3.16.y-ckt 054/183] mmc: sdhci-pxav3: fix race between runtime pm and irq

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Message-Id: <1425635874-19087-55-git-send-email-luis.henriques@canonical.com>
Date:	Fri,  6 Mar 2015 09:55:45 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jisheng Zhang <jszhang@...vell.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 054/183] mmc: sdhci-pxav3: fix race between runtime pm and irq

3.16.7-ckt8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jisheng Zhang <jszhang@...vell.com>

commit 3bb10f60933e84abfe2be69f60b3486f9b96348b upstream.

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@...vell.com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/mmc/host/sdhci-pxav3.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/host/sdhci-pxav3.c b/drivers/mmc/host/sdhci-pxav3.c
index f62655bc1604..a30f42003fb8 100644
--- a/drivers/mmc/host/sdhci-pxav3.c
+++ b/drivers/mmc/host/sdhci-pxav3.c
@@ -448,11 +448,11 @@ 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);
-	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);
+	if (ret)
+		return ret;
 
 	clk_disable_unprepare(pltfm_host->clk);
 
@@ -463,15 +463,10 @@ 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);
-	unsigned long flags;
 
 	clk_prepare_enable(pltfm_host->clk);
 
-	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
 
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