[3.16.y-ckt stable] Patch "mmc: sdhci-pxav3: fix race between runtime pm and irq" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 44baa458dcdf872ebd51c1c44276e5d1bdf8a92f Mon Sep 17 00:00:00 2001
From: Jisheng Zhang <jszhang at marvell.com>
Date: Fri, 23 Jan 2015 18:08:21 +0800
Subject: mmc: sdhci-pxav3: fix race between runtime pm and irq

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 at marvell.com>
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.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