The patch titled
oprofile: fix hang while offline the cpu
has been removed from the -mm tree. Its filename was
oprofile-fix-hang-while-offline-the-cpu.patch
This patch was dropped because an alternative patch was merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: oprofile: fix hang while offline the cpu
From: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
The kernel is built with CONFIG_OPROFILE and CPU_HOTPLUG enabled.
oprofile is initialised using system timer in absence of hardware counters
supports. Oprofile isn't started from userland.
In this setup while doing a CPU offline the kernel hangs in an infinite
loop in lock_hrtimer_base().
This happens because as part of oprofile_cpu_notify(, it tries to stop an
hrtimer which was never started. These per-cpu hrtimers are started when
the oprfile is started.
echo 1 > /dev/oprofile/enable
Fix this issue by adding a state variable so that these hrtimer start/stop
is only attempted when oprofile is started
Reported-by: Jan Sebastien <s-jan@xxxxxx>
Signed-off-by: sricharan <r.sricharan@xxxxxx>
Tested-by: sricharan <r.sricharan@xxxxxx>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>
Cc: Robert Richter <robert.richter@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/oprofile/timer_int.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff -puN drivers/oprofile/timer_int.c~oprofile-fix-hang-while-offline-the-cpu drivers/oprofile/timer_int.c
--- a/drivers/oprofile/timer_int.c~oprofile-fix-hang-while-offline-the-cpu
+++ a/drivers/oprofile/timer_int.c
@@ -21,6 +21,7 @@
#include "oprof.h"
static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
+static int oprofile_hrtimer_started;
static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
{
@@ -33,6 +34,9 @@ static void __oprofile_hrtimer_start(voi
{
struct hrtimer *hrtimer = &__get_cpu_var(oprofile_hrtimer);
+ if (!oprofile_hrtimer_started)
+ return;
+
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = oprofile_hrtimer_notify;
@@ -42,6 +46,7 @@ static void __oprofile_hrtimer_start(voi
static int oprofile_hrtimer_start(void)
{
+ oprofile_hrtimer_started = 1;
on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
return 0;
}
@@ -50,6 +55,9 @@ static void __oprofile_hrtimer_stop(int
{
struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);
+ if (!oprofile_hrtimer_started)
+ return;
+
hrtimer_cancel(hrtimer);
}
@@ -59,6 +67,7 @@ static void oprofile_hrtimer_stop(void)
for_each_online_cpu(cpu)
__oprofile_hrtimer_stop(cpu);
+ oprofile_hrtimer_started = 0;
}
static int __cpuinit oprofile_cpu_notify(struct notifier_block *self,
_
Patches currently in -mm which might be from santosh.shilimkar@xxxxxx are
origin.patch
linux-next.patch
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