The patch titled
Subject: rtc: armada38x: fix concurrency access in armada38x_rtc_set_time
has been added to the -mm tree. Its filename is
rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time.patch
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------------------------------------------------------
From: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Subject: rtc: armada38x: fix concurrency access in armada38x_rtc_set_time
While setting the time, the RTC TIME register should not be accessed.
However due to hardware constraints, setting the RTC time involves
sleeping during 100ms. This sleep was done outside the critical section
protected by the spinlock, so it was possible to read the RTC TIME
register and get an incorrect value. This patch introduces a mutex for
protecting the RTC TIME access, unlike the spinlock it is allowed to sleep
in a critical section protected by a mutex. The RTC STATUS register can
still be used from the interrupt handler but it has no effect on setting
the time.
Signed-off-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx>
Acked-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Acked-by: Andrew Lunn <andrew@xxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.0]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-armada38x.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff -puN drivers/rtc/rtc-armada38x.c~rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time drivers/rtc/rtc-armada38x.c
--- a/drivers/rtc/rtc-armada38x.c~rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time
+++ a/drivers/rtc/rtc-armada38x.c
@@ -40,6 +40,13 @@ struct armada38x_rtc {
void __iomem *regs;
void __iomem *regs_soc;
spinlock_t lock;
+ /*
+ * While setting the time, the RTC TIME register should not be
+ * accessed. Setting the RTC time involves sleeping during
+ * 100ms, so a mutex instead of a spinlock is used to protect
+ * it
+ */
+ struct mutex mutex_time;
int irq;
};
@@ -59,8 +66,7 @@ static int armada38x_rtc_read_time(struc
struct armada38x_rtc *rtc = dev_get_drvdata(dev);
unsigned long time, time_check, flags;
- spin_lock_irqsave(&rtc->lock, flags);
-
+ mutex_lock(&rtc->mutex_time);
time = readl(rtc->regs + RTC_TIME);
/*
* WA for failing time set attempts. As stated in HW ERRATA if
@@ -71,7 +77,7 @@ static int armada38x_rtc_read_time(struc
if ((time_check - time) > 1)
time_check = readl(rtc->regs + RTC_TIME);
- spin_unlock_irqrestore(&rtc->lock, flags);
+ mutex_unlock(&rtc->mutex_time);
rtc_time_to_tm(time_check, tm);
@@ -94,19 +100,12 @@ static int armada38x_rtc_set_time(struct
* then wait for 100ms before writing to the time register to be
* sure that the data will be taken into account.
*/
- spin_lock_irqsave(&rtc->lock, flags);
-
+ mutex_lock(&rtc->mutex_time);
rtc_delayed_write(0, rtc, RTC_STATUS);
-
- spin_unlock_irqrestore(&rtc->lock, flags);
-
msleep(100);
-
- spin_lock_irqsave(&rtc->lock, flags);
-
rtc_delayed_write(time, rtc, RTC_TIME);
+ mutex_unlock(&rtc->mutex_time);
- spin_unlock_irqrestore(&rtc->lock, flags);
out:
return ret;
}
@@ -230,6 +229,7 @@ static __init int armada38x_rtc_probe(st
return -ENOMEM;
spin_lock_init(&rtc->lock);
+ mutex_init(&rtc->mutex_time);
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rtc");
rtc->regs = devm_ioremap_resource(&pdev->dev, res);
_
Patches currently in -mm which might be from gregory.clement@xxxxxxxxxxxxxxxxxx are
rtc-armada38x-fix-concurrency-access-in-armada38x_rtc_set_time.patch
linux-next.patch
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