Prev: core/hweight changes for v2.6.35
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From: Don Zickus on 17 May 2010 18:10
These options broke during this rewrite. The previous patch cleaned
up the internals. This patch actually uses those changes to allow
one to properly use nmi_watchdog=0 and nosoftlockup from the kernel
commandline and the bash shell.

The downside of these changes is I removed the global option of
'watchdog' that would have enabled/disabled both the hardlockup
and softlockup detector (as if they were one).

Signed-off-by: Don Zickus <dzickus(a)redhat.com>
---
arch/x86/include/asm/nmi.h | 2 -
include/linux/nmi.h | 4 +-
kernel/sysctl.c | 15 +++++-
kernel/watchdog.c | 103 ++++++++++++++++++++++++++-----------------
4 files changed, 76 insertions(+), 48 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 932f0f8..93da9c3 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -17,9 +17,7 @@ int do_nmi_callback(struct pt_regs *regs, int cpu);

extern void die_nmi(char *str, struct pt_regs *regs, int do_panic);
extern int check_nmi_watchdog(void);
-#if !defined(CONFIG_LOCKUP_DETECTOR)
extern int nmi_watchdog_enabled;
-#endif
extern int avail_to_resrv_perfctr_nmi_bit(unsigned int);
extern int reserve_perfctr_nmi(unsigned int);
extern void release_perfctr_nmi(unsigned int);
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 06aab5e..d075b3a 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -54,9 +54,9 @@ static inline bool trigger_all_cpu_backtrace(void)
#ifdef CONFIG_LOCKUP_DETECTOR
int hw_nmi_is_cpu_stuck(struct pt_regs *);
u64 hw_nmi_get_sample_period(void);
-extern int watchdog_enabled;
+extern int softlockup_watchdog_enabled;
struct ctl_table;
-extern int proc_dowatchdog_enabled(struct ctl_table *, int ,
+extern int proc_softlockup_enabled(struct ctl_table *, int ,
void __user *, size_t *, loff_t *);
#endif

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 04bcd8a..e856655 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -688,11 +688,11 @@ static struct ctl_table kern_table[] = {
},
#if defined(CONFIG_LOCKUP_DETECTOR)
{
- .procname = "watchdog",
- .data = &watchdog_enabled,
+ .procname = "softlockup_watchdog",
+ .data = &softlockup_watchdog_enabled,
.maxlen = sizeof (int),
.mode = 0644,
- .proc_handler = proc_dowatchdog_enabled,
+ .proc_handler = proc_softlockup_enabled
},
{
.procname = "watchdog_thresh",
@@ -712,6 +712,15 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
},
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
+ {
+ .procname = "nmi_watchdog",
+ .data = &nmi_watchdog_enabled,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = proc_nmi_enabled,
+ },
+#endif
#endif
#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) && !defined(CONFIG_LOCKUP_DETECTOR)
{
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 0a6bdb7..f3c63a8 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -27,7 +27,6 @@
#include <asm/irq_regs.h>
#include <linux/perf_event.h>

-int watchdog_enabled;
int __read_mostly softlockup_thresh = 60;

typedef void (*callback_t)(void);
@@ -47,7 +46,14 @@ static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
#endif

static int __read_mostly did_panic;
-static int __initdata no_watchdog;
+
+#define LOCKUP_DETECT_DISABLED -1
+#define LOCKUP_DETECT_OFF 0
+#define LOCKUP_DETECT_ON 1
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
+int nmi_watchdog_enabled = LOCKUP_DETECT_OFF;
+#endif
+int softlockup_watchdog_enabled = LOCKUP_DETECT_OFF;


/* boot commands */
@@ -59,8 +65,19 @@ static int hardlockup_panic;

static int __init hardlockup_panic_setup(char *str)
{
- if (!strncmp(str, "panic", 5))
+ unsigned int nmi;
+
+ if (!strncmp(str, "panic", 5)) {
hardlockup_panic = 1;
+ str = strchr(str, ',');
+ if (!str)
+ return 1;
+ ++str;
+ }
+ get_option(&str, &nmi);
+ if (nmi == 0)
+ nmi_watchdog_enabled = LOCKUP_DETECT_DISABLED;
+
return 1;
}
__setup("nmi_watchdog=", hardlockup_panic_setup);
@@ -77,21 +94,12 @@ static int __init softlockup_panic_setup(char *str)
}
__setup("softlockup_panic=", softlockup_panic_setup);

-static int __init nowatchdog_setup(char *str)
-{
- no_watchdog = 1;
- return 1;
-}
-__setup("nowatchdog", nowatchdog_setup);
-
-/* deprecated */
static int __init nosoftlockup_setup(char *str)
{
- no_watchdog = 1;
+ softlockup_watchdog_enabled = LOCKUP_DETECT_DISABLED;
return 1;
}
__setup("nosoftlockup", nosoftlockup_setup);
-/* */


/*
@@ -338,6 +346,7 @@ static int watchdog(void *unused)
HRTIMER_MODE_REL_PINNED);

set_current_state(TASK_INTERRUPTIBLE);
+
/*
* Run briefly once per second to reset the softlockup timestamp.
* If this gets delayed for more than 60 seconds then the
@@ -364,6 +373,10 @@ static int watchdog_nmi_enable(int cpu)
struct perf_event_attr *wd_attr;
struct perf_event *event = per_cpu(watchdog_ev, cpu);

+ /* boot param says don't enable */
+ if (nmi_watchdog_enabled == LOCKUP_DETECT_DISABLED)
+ return 0;
+
/* is it already setup and enabled? */
if (event && event->state > PERF_EVENT_STATE_OFF)
goto out;
@@ -390,6 +403,7 @@ out_save:
out_enable:
perf_event_enable(per_cpu(watchdog_ev, cpu));
out:
+ nmi_watchdog_enabled = LOCKUP_DETECT_ON;
return 0;
}

@@ -414,8 +428,13 @@ static void watchdog_nmi_disable(int cpu) { return; }
static int watchdog_softlockup_enable(int cpu)
{
/* if any cpu succeeds, watchdog is considered enabled for the system */
+ /* skip if DISABLED */
+ if (softlockup_watchdog_enabled == LOCKUP_DETECT_DISABLED)
+ return 0;
+
per_cpu(softlockup_callback, cpu) = watchdog_softlockup_callback;
wake_up_process(per_cpu(watchdog_thread, cpu));
+ softlockup_watchdog_enabled = LOCKUP_DETECT_ON;

return 0;
}
@@ -491,46 +510,51 @@ static void watchdog_disable(int cpu)
}
}

-static void watchdog_enable_all_cpus(void)
+/* sysctl functions */
+#ifdef CONFIG_SYSCTL
+/*
+ * proc handler for /proc/sys/kernel/nmi_watchdog
+ */
+
+#ifdef CONFIG_HARDLOCKUP_DETECTOR
+int proc_nmi_enabled(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
{
int cpu;
- int result;
+ int result=0;
+
+ proc_dointvec(table, write, buffer, length, ppos);

for_each_online_cpu(cpu)
- result += watchdog_enable(cpu);
+ if (nmi_watchdog_enabled)
+ result += watchdog_nmi_enable(cpu);
+ else
+ watchdog_nmi_disable(cpu);

if (result)
- printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
+ printk(KERN_ERR "watchdog: hardlockup failed to be enabled on some cpus\n");

+ return 0;
}
+#endif

-static void watchdog_disable_all_cpus(void)
+int proc_softlockup_enabled(struct ctl_table *table, int write,
+ void __user *buffer, size_t *length, loff_t *ppos)
{
int cpu;
+ int result=0;

- for_each_online_cpu(cpu)
- watchdog_disable(cpu);
-
- /* if all watchdogs are disabled, then they are disabled for the system */
- watchdog_enabled = 0;
-}
-
+ proc_dointvec(table, write, buffer, length, ppos);

-/* sysctl functions */
-#ifdef CONFIG_SYSCTL
-/*
- * proc handler for /proc/sys/kernel/nmi_watchdog
- */
+ for_each_online_cpu(cpu)
+ if (softlockup_watchdog_enabled)
+ result += watchdog_softlockup_enable(cpu);
+ else
+ watchdog_softlockup_disable(cpu);

-int proc_dowatchdog_enabled(struct ctl_table *table, int write,
- void __user *buffer, size_t *length, loff_t *ppos)
-{
- proc_dointvec(table, write, buffer, length, ppos);
+ if (result)
+ printk(KERN_ERR "watchdog: softlockup failed to be enabled on some cpus\n");

- if (watchdog_enabled)
- watchdog_enable_all_cpus();
- else
- watchdog_disable_all_cpus();
return 0;
}

@@ -585,9 +609,6 @@ static int __init spawn_watchdog_task(void)
void *cpu = (void *)(long)smp_processor_id();
int err;

- if (no_watchdog)
- return 0;
-
err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
WARN_ON(err == NOTIFY_BAD);

--
1.7.0.1

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Prev: core/hweight changes for v2.6.35
Next: [PATCH 08/10] rwsem: down_read_critical infrastructure support