The patch titled
time: fix msecs_to_jiffies() bug
has been removed from the -mm tree. Its filename is
time-fix-msecs_to_jiffies-bug.patch
This patch was dropped because an updated version was merged
------------------------------------------------------
Subject: time: fix msecs_to_jiffies() bug
From: Ingo Molnar <mingo@xxxxxxx>
Fix multiple conversion bugs in msecs_to_jiffies().
The main problem is that this condition:
if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
overflows if HZ is smaller than 1000!
This change is user-visible: for HZ=250 SUS-compliant poll()-timeout value of
-20 is mistakenly converted to 'immediate timeout'.
(The new dyntick code also triggered this, as it frequently creates 'lagging
timer wheel' scenarios.)
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: john stultz <johnstul@xxxxxxxxxx>
Cc: Roman Zippel <zippel@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/time.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 42 insertions(+), 1 deletion(-)
diff -puN kernel/time.c~time-fix-msecs_to_jiffies-bug kernel/time.c
--- a/kernel/time.c~time-fix-msecs_to_jiffies-bug
+++ a/kernel/time.c
@@ -500,15 +500,56 @@ unsigned int jiffies_to_usecs(const unsi
}
EXPORT_SYMBOL(jiffies_to_usecs);
+/*
+ * When we convert to jiffies then we interpret incoming values
+ * the following way:
+ *
+ * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
+ *
+ * - 'too large' values [that would result in larger than
+ * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
+ *
+ * - all other values are converted to jiffies by either multiplying
+ * the input value by a factor or dividing it with a factor
+ *
+ * We must also be careful about 32-bit overflows.
+ */
unsigned long msecs_to_jiffies(const unsigned int m)
{
- if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
+ /*
+ * Negative value, means infinite timeout:
+ */
+ if ((int)m < 0)
return MAX_JIFFY_OFFSET;
+
#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
+ /*
+ * HZ is equal to or smaller than 1000, and 1000 is a nice
+ * round multiple of HZ, divide with the factor between them,
+ * but round upwards:
+ */
return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
+ /*
+ * HZ is larger than 1000, and HZ is a nice round multiple of
+ * 1000 - simply multiply with the factor between them.
+ *
+ * But first make sure the multiplication result cannot
+ * overflow:
+ */
+ if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
+ return MAX_JIFFY_OFFSET;
+
return m * (HZ / MSEC_PER_SEC);
#else
+ /*
+ * Generic case - multiply, round and divide. But first
+ * check that if we are doing a net multiplication, that
+ * we wouldnt overflow:
+ */
+ if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
+ return MAX_JIFFY_OFFSET;
+
return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
#endif
}
_
Patches currently in -mm which might be from mingo@xxxxxxx are
forcedeth-hardirq-lockdep-warning.patch
bonding-lockdep-annotation.patch
spinlock-debug-all-cpu-backtrace.patch
spinlock-debug-all-cpu-backtrace-fix.patch
spinlock-debug-all-cpu-backtrace-fix-2.patch
spinlock-debug-all-cpu-backtrace-fix-3.patch
remove-the-old-bd_mutex-lockdep-annotation.patch
new-bd_mutex-lockdep-annotation.patch
sched-add-above-background-load-function.patch
mm-implement-swap-prefetching.patch
sched-cleanup-remove-task_t-convert-to-struct-task_struct-prefetch.patch
time-fix-msecs_to_jiffies-bug.patch
time-fix-timeout-overflow.patch
cleanup-uninline-irq_enter-and-move-it-into-a.patch
dynticks-extend-next_timer_interrupt-to-use-a.patch
hrtimers-namespace-and-enum-cleanup.patch
hrtimers-clean-up-locking.patch
hrtimers-state-tracking.patch
hrtimers-state-tracking-fix.patch
hrtimers-clean-up-callback-tracking.patch
hrtimers-move-and-add-documentation.patch
clockevents-core.patch
clockevents-drivers-for-i386.patch
clockevents-drivers-for-i386-fix.patch
clockevents-drivers-for-i386-fix-2.patch
clockevents-drivers-for-i386-mystery-fix.patch
high-res-timers-core.patch
high-res-timers-core-fix.patch
high-res-timers-core-fix-2.patch
dynticks-core.patch
dynticks-core-nmi-watchdog-fix.patch
dynticks-core-nmi-watchdog-fix-2.patch
dynticks-core-fix-idle-time-accounting.patch
dyntick-add-nohz-stats-to-proc-stat.patch
dynticks-i386-arch-code.patch
high-res-timers-dynticks-enable-i386-support.patch
debugging-feature-timer-stats.patch
debugging-feature-timer-stats-fix.patch
detect-atomic-counter-underflows.patch
debug-shared-irqs.patch
make-frame_pointer-default=y.patch
mutex-subsystem-synchro-test-module.patch
vdso-print-fatal-signals.patch
vdso-improve-print_fatal_signals-support-by-adding-memory-maps.patch
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