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authorUlrich Obergfell <uobergfe@redhat.com>2015-09-04 15:45:28 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-04 16:54:41 -0700
commitec6a90661a0d6ce1461d05c7a58a0a151154e14a (patch)
tree54dcb55b4d38eb60c4eef1366b7d5d8ef4ea2d5d
parent999bbe49ea0118b70ddf3f5d679f51dc7a97ae55 (diff)
watchdog: rename watchdog_suspend() and watchdog_resume()
Rename watchdog_suspend() to lockup_detector_suspend() and watchdog_resume() to lockup_detector_resume() to avoid confusion with the watchdog subsystem and to be consistent with the existing name lockup_detector_init(). Also provide comment blocks to explain the watchdog_running and watchdog_suspended variables and their relationship. Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Reviewed-by: Aaron Tomlin <atomlin@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Stephane Eranian <eranian@google.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel.c4
-rw-r--r--include/linux/nmi.h8
-rw-r--r--kernel/watchdog.c26
3 files changed, 28 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 144ab91951a7..cd9b6d0b10bf 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -3627,7 +3627,7 @@ static __init int fixup_ht_bug(void)
return 0;
}
- if (watchdog_suspend() != 0) {
+ if (lockup_detector_suspend() != 0) {
pr_debug("failed to disable PMU erratum BJ122, BV98, HSD29 workaround\n");
return 0;
}
@@ -3638,7 +3638,7 @@ static __init int fixup_ht_bug(void)
x86_pmu.commit_scheduling = NULL;
x86_pmu.stop_scheduling = NULL;
- watchdog_resume();
+ lockup_detector_resume();
get_online_cpus();
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index e5afe8bae202..a91adf6e02f2 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -78,15 +78,15 @@ extern int proc_watchdog_thresh(struct ctl_table *, int ,
void __user *, size_t *, loff_t *);
extern int proc_watchdog_cpumask(struct ctl_table *, int,
void __user *, size_t *, loff_t *);
-extern int watchdog_suspend(void);
-extern void watchdog_resume(void);
+extern int lockup_detector_suspend(void);
+extern void lockup_detector_resume(void);
#else
-static inline int watchdog_suspend(void)
+static inline int lockup_detector_suspend(void)
{
return 0;
}
-static inline void watchdog_resume(void)
+static inline void lockup_detector_resume(void)
{
}
#endif
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 69666f4b8e8f..64ed1c37bd1f 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -67,8 +67,26 @@ unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
#define for_each_watchdog_cpu(cpu) \
for_each_cpu_and((cpu), cpu_online_mask, &watchdog_cpumask)
-static int __read_mostly watchdog_suspended;
+/*
+ * The 'watchdog_running' variable is set to 1 when the watchdog threads
+ * are registered/started and is set to 0 when the watchdog threads are
+ * unregistered/stopped, so it is an indicator whether the threads exist.
+ */
static int __read_mostly watchdog_running;
+/*
+ * If a subsystem has a need to deactivate the watchdog temporarily, it
+ * can use the suspend/resume interface to achieve this. The content of
+ * the 'watchdog_suspended' variable reflects this state. Existing threads
+ * are parked/unparked by the lockup_detector_{suspend|resume} functions
+ * (see comment blocks pertaining to those functions for further details).
+ *
+ * 'watchdog_suspended' also prevents threads from being registered/started
+ * or unregistered/stopped via parameters in /proc/sys/kernel, so the state
+ * of 'watchdog_running' cannot change while the watchdog is deactivated
+ * temporarily (see related code in 'proc' handlers).
+ */
+static int __read_mostly watchdog_suspended;
+
static u64 __read_mostly sample_period;
static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
@@ -669,7 +687,7 @@ static void watchdog_unpark_threads(void)
/*
* Suspend the hard and soft lockup detector by parking the watchdog threads.
*/
-int watchdog_suspend(void)
+int lockup_detector_suspend(void)
{
int ret = 0;
@@ -679,7 +697,7 @@ int watchdog_suspend(void)
* the 'watchdog_suspended' variable). If the watchdog threads are
* running, the first caller takes care that they will be parked.
* The state of 'watchdog_running' cannot change while a suspend
- * request is active (see related changes in 'proc' handlers).
+ * request is active (see related code in 'proc' handlers).
*/
if (watchdog_running && !watchdog_suspended)
ret = watchdog_park_threads();
@@ -695,7 +713,7 @@ int watchdog_suspend(void)
/*
* Resume the hard and soft lockup detector by unparking the watchdog threads.
*/
-void watchdog_resume(void)
+void lockup_detector_resume(void)
{
mutex_lock(&watchdog_proc_mutex);