* [PATCH] Fix overflow when HZ is smaller than 60
@ 2014-01-24 17:21 Mikulas Patocka
2014-01-24 21:41 ` [PATCH v2] " Mikulas Patocka
0 siblings, 1 reply; 3+ messages in thread
From: Mikulas Patocka @ 2014-01-24 17:21 UTC (permalink / raw)
To: John Stultz, Thomas Gleixner; +Cc: linux-kernel
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: stable@vger.kernel.org
---
kernel/time/jiffies.c | 6 ++++++
1 file changed, 6 insertions(+)
Index: linux-2.6-ia64/kernel/time/jiffies.c
===================================================================
--- linux-2.6-ia64.orig/kernel/time/jiffies.c 2014-01-24 17:48:48.000000000 +0100
+++ linux-2.6-ia64/kernel/time/jiffies.c 2014-01-24 18:14:51.000000000 +0100
@@ -51,7 +51,13 @@
* HZ shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
*/
+#if HZ < 30
+#define JIFFIES_SHIFT 6
+#elif HZ < 60
+#define JIFFIES_SHIFT 7
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v2] Fix overflow when HZ is smaller than 60
2014-01-24 17:21 [PATCH] Fix overflow when HZ is smaller than 60 Mikulas Patocka
@ 2014-01-24 21:41 ` Mikulas Patocka
2014-02-06 15:04 ` [tip:timers/urgent] time: " tip-bot for Mikulas Patocka
0 siblings, 1 reply; 3+ messages in thread
From: Mikulas Patocka @ 2014-01-24 21:41 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: linux-kernel
The patch that I sent before had wrong numbers in it, it could result in
"Clocksource jiffies might overflow on 11% adjustment" message. This is
the patch with correct numbers.
> +#if HZ < 30
> +#define JIFFIES_SHIFT 6
> +#elif HZ < 60
> +#define JIFFIES_SHIFT 7
> +#else
> #define JIFFIES_SHIFT 8
> +#endif
From: Mikulas Patocka <mpatocka@redhat.com>
Fix overflow when HZ is 32
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: stable@vger.kernel.org
---
kernel/time/jiffies.c | 6 ++++++
1 file changed, 6 insertions(+)
Index: linux-2.6-ia64/kernel/time/jiffies.c
===================================================================
--- linux-2.6-ia64.orig/kernel/time/jiffies.c 2014-01-24 22:34:17.000000000 +0100
+++ linux-2.6-ia64/kernel/time/jiffies.c 2014-01-24 22:36:56.000000000 +0100
@@ -51,7 +51,13 @@
* HZ shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
*/
+#if HZ < 34
+#define JIFFIES_SHIFT 6
+#elif HZ < 67
+#define JIFFIES_SHIFT 7
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip:timers/urgent] time: Fix overflow when HZ is smaller than 60
2014-01-24 21:41 ` [PATCH v2] " Mikulas Patocka
@ 2014-02-06 15:04 ` tip-bot for Mikulas Patocka
0 siblings, 0 replies; 3+ messages in thread
From: tip-bot for Mikulas Patocka @ 2014-02-06 15:04 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, mikulas, tglx, mpatocka
Commit-ID: 80d767d770fd9c697e434fd080c2db7b5c60c6dd
Gitweb: http://git.kernel.org/tip/80d767d770fd9c697e434fd080c2db7b5c60c6dd
Author: Mikulas Patocka <mpatocka@redhat.com>
AuthorDate: Fri, 24 Jan 2014 16:41:36 -0500
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 6 Feb 2014 16:01:40 +0100
time: Fix overflow when HZ is smaller than 60
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1401241639100.23871@file01.intranet.prod.int.rdu2.redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/jiffies.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 7a925ba..a6a5bf5 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -51,7 +51,13 @@
* HZ shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
*/
+#if HZ < 34
+#define JIFFIES_SHIFT 6
+#elif HZ < 67
+#define JIFFIES_SHIFT 7
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2014-01-24 17:21 [PATCH] Fix overflow when HZ is smaller than 60 Mikulas Patocka
2014-01-24 21:41 ` [PATCH v2] " Mikulas Patocka
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