The patch titled
Subject: rtc: snvs: change timeout to use a fixed number of loop
has been added to the -mm tree. Its filename is
rtc-snvs-add-freescale-rtc-snvs-driver-fix.patch
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From: Shawn Guo <shawn.guo@xxxxxxxxxx>
Subject: rtc: snvs: change timeout to use a fixed number of loop
Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> The timeout code here is fragile. If acquiring the spinlock takes more
> than a millisecond or if this thread gets interrupted or preempted then
> we could easily execute that loop just a single time, and fail.
>
> It would be better to retry a fixed number of times, say 1000? That
> would take around 1 millisecond, but might be overkill.
Take Andrew's suggestion to change the timeout code to retry 1000
times.
Signed-off-by: Shawn Guo <shawn.guo@xxxxxxxxxx>
Cc: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Kim Phillips <kim.phillips@xxxxxxxxxxxxx>
Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-snvs.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN drivers/rtc/rtc-snvs.c~rtc-snvs-add-freescale-rtc-snvs-driver-fix drivers/rtc/rtc-snvs.c
--- a/drivers/rtc/rtc-snvs.c~rtc-snvs-add-freescale-rtc-snvs-driver-fix
+++ a/drivers/rtc/rtc-snvs.c
@@ -83,8 +83,8 @@ static void rtc_write_sync_lp(void __iom
static int snvs_rtc_enable(struct snvs_rtc_data *data, bool enable)
{
- unsigned long timeout = jiffies + msecs_to_jiffies(1);
unsigned long flags;
+ int timeout = 1000;
u32 lpcr;
spin_lock_irqsave(&data->lock, flags);
@@ -98,7 +98,7 @@ static int snvs_rtc_enable(struct snvs_r
spin_unlock_irqrestore(&data->lock, flags);
- while (1) {
+ while (--timeout) {
lpcr = readl(data->ioaddr + SNVS_LPCR);
if (enable) {
@@ -108,11 +108,11 @@ static int snvs_rtc_enable(struct snvs_r
if (!(lpcr & SNVS_LPCR_SRTC_ENV))
break;
}
-
- if (time_after(jiffies, timeout))
- return -ETIMEDOUT;
}
+ if (!timeout)
+ return -ETIMEDOUT;
+
return 0;
}
_
Patches currently in -mm which might be from shawn.guo@xxxxxxxxxx are
linux-next.patch
rtc-snvs-add-freescale-rtc-snvs-driver.patch
rtc-snvs-add-freescale-rtc-snvs-driver-fix.patch
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