The patch titled
hpet: fix the possibility of insane return value of hpet_calibrate() against SMI
has been added to the -mm tree. Its filename is
hpet-fix-the-possibility-of-insane-return-value-of-hpet_calibrate-against-smi.patch
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------------------------------------------------------
Subject: hpet: fix the possibility of insane return value of hpet_calibrate() against SMI
From: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
hpet_calibrate() has a possibility of miss-calibration due to SMI. If SMI
interrupts in the while loop of calibration, then return value will be
big. This change calibrates until stabilizing by the return value with a
small value.
Signed-off-by: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
Acked-by: Clemens Ladisch <clemens@xxxxxxxxxx>
Acked-by: Vojtech Pavlik <vojtech@xxxxxxx>
Cc: Robert Picco <Robert.Picco@xxxxxx>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/hpet.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff -puN drivers/char/hpet.c~hpet-fix-the-possibility-of-insane-return-value-of-hpet_calibrate-against-smi drivers/char/hpet.c
--- a/drivers/char/hpet.c~hpet-fix-the-possibility-of-insane-return-value-of-hpet_calibrate-against-smi
+++ a/drivers/char/hpet.c
@@ -713,7 +713,7 @@ static struct ctl_table_header *sysctl_h
*/
#define TICK_CALIBRATE (1000UL)
-static unsigned long hpet_calibrate(struct hpets *hpetp)
+static unsigned long __hpet_calibrate(struct hpets *hpetp)
{
struct hpet_timer __iomem *timer = NULL;
unsigned long t, m, count, i, flags, start;
@@ -750,6 +750,25 @@ static unsigned long hpet_calibrate(stru
return (m - start) / i;
}
+static unsigned long hpet_calibrate(struct hpets *hpetp)
+{
+ unsigned long ret = ~0UL, tmp;
+
+ /*
+ * Try to calibrate until return value becomes stable small value.
+ * If SMI interruption occurs in calibration loop, the return value
+ * will be big. This avoids its impact.
+ */
+ do {
+ tmp = __hpet_calibrate(hpetp);
+ if (ret <= tmp)
+ break;
+ ret = tmp;
+ } while (1);
+
+ return ret;
+}
+
int hpet_alloc(struct hpet_data *hdp)
{
u64 cap, mcfg;
_
Patches currently in -mm which might be from y-goto@xxxxxxxxxxxxxx are
linux-next.patch
hpet-fix-the-possibility-of-insane-return-value-of-hpet_calibrate-against-smi.patch
hpet-fix-the-possibility-of-insane-return-value-of-hpet_calibrate-against-smi-fix.patch
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