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INFO: suspicious RCU usage for 3.5-rc1+

BUG In review Feng Tang 3 participants 8 messages Jun 12, 2012 – Jul 4, 2012 LED

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Feng Tang

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#0 lore raw

During Fengguang's build test, we found a problem here:

(x86_64-allyesdebian config)

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal context switch in RCU read-side critical section!
[ 1526.520230]  
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]  
[ 1526.520230]  
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>] do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>] panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>] rcu_lock_acquire+0x0/0x29
[ 1526.520230]  
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>] __atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

Seems it is caused by doing sleepable option in led_trigger_unregister() inside the panic atomic environment.

The original commit is:
commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4

Author: Alexander Holler <[email protected]>
Date:   Tue May 29 15:07:29 2012 -0700

leds: heartbeat: stop on shutdown

A halted kernel should not show a heartbeat.

Thanks,
Feng

#1 lore raw

Hello Feng,

sorry for the late answer.

Am 12.06.2012 10:26, schrieb Feng Tang:

Quoted 39 lines

During Fengguang's build test, we found a problem here:

(x86_64-allyesdebian config)

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal context switch in RCU read-side critical section!
[ 1526.520230]
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]
[ 1526.520230]
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>] do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>] panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>] rcu_lock_acquire+0x0/0x29
[ 1526.520230]
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>] __atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

Seems it is caused by doing sleepable option in led_trigger_unregister() inside the panic atomic environment.

Quoted 9 lines

The original commit is:
commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4

Author: Alexander Holler <[email protected]>
Date:   Tue May 29 15:07:29 2012 -0700

leds: heartbeat: stop on shutdown

A halted kernel should not show a heartbeat.

Hmm, I'm not very familiar with what happens when a panic occurs and my tests with panics haven't revealed that (or I didn't have seen it).

I will try to get the same error and will have a deeper look at what happens in led_trigger_unregister() (and if and how that might be avoidable) in the next days. Thanks.

Regards,

Alexander

#2 lore raw

PATCH 1/1 leds: heartbeat: fix bug on panic

In reply to Feng Tang

With commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4 I introduced a bug (visible if CONFIG_PROVE_RCU is enabled) which occures when a panic has happened:

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal context switch in RCU read-side critical section!
[ 1526.520230]
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]
[ 1526.520230]
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>] do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>] panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>] rcu_lock_acquire+0x0/0x29
[ 1526.520230]
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>] __atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

So in case of a panic, now just turn of the LED. Other approaches like scheduling a work to unregister the trigger aren't working because there isn't much which still runs after a panic occured (except timers).

Signed-off-by Alexander Holler <[email protected]>
---
 drivers/leds/ledtrig-heartbeat.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
drivers/leds/ledtrig-heartbeat.c +15 -1
index 41dc76d..a019fbb 100644
@@ -21,6 +21,8 @@
 #include <linux/reboot.h>
 #include "leds.h"
 
+static int panic_heartbeats;
+
 struct heartbeat_trig_data {
 	unsigned int phase;
 	unsigned int period;

@@ -34,6 +36,11 @@ static void led_heartbeat_function(unsigned long data)
 	unsigned long brightness = LED_OFF;
 	unsigned long delay = 0;
 
+	if (unlikely(panic_heartbeats)) {
+		led_set_brightness(led_cdev, LED_OFF);
+		return;
+	}
+
 	/* acts like an actual heart beat -- ie thump-thump-pause... */
 	switch (heartbeat_data->phase) {
 	case 0:

@@ -111,12 +118,19 @@ static int heartbeat_reboot_notifier(struct notifier_block *nb,
 	return NOTIFY_DONE;
 }
 
+static int heartbeat_panic_notifier(struct notifier_block *nb,
+				     unsigned long code, void *unused)
+{
+	panic_heartbeats = 1;
+	return NOTIFY_DONE;
+}
+
 static struct notifier_block heartbeat_reboot_nb = {
 	.notifier_call = heartbeat_reboot_notifier,
 };
 
 static struct notifier_block heartbeat_panic_nb = {
-	.notifier_call = heartbeat_reboot_notifier,
+	.notifier_call = heartbeat_panic_notifier,
 };
 
 static int __init heartbeat_trig_init(void)
Signature · 1 line
1.7.6.5
#3 lore raw

Re: [PATCH] leds: heartbeat: fix bug on panic

Quoted 70 lines · Alexander Holler

With commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4 I introduced a bug (visible if CONFIG_PROVE_RCU is enabled) which occures when a panic has happened:

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal context switch in RCU read-side critical section!
[ 1526.520230]
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]
[ 1526.520230]
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>] do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>] panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>] rcu_lock_acquire+0x0/0x29
[ 1526.520230]
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>] __atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

So in case of a panic, now just turn of the LED. Other approaches like scheduling a work to unregister the trigger aren't working because there isn't much which still runs after a panic occured (except timers).

Signed-off-by Alexander Holler <[email protected]>
---
 drivers/leds/ledtrig-heartbeat.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)
drivers/leds/ledtrig-heartbeat.c +7 -0
index 41dc76d..a019fbb 100644
@@ -21,6 +21,8 @@
 #include <linux/reboot.h>
 #include "leds.h"
 
+static int panic_heartbeats;
+
 struct heartbeat_trig_data {
        unsigned int phase;
        unsigned int period;

@@ -34,6 +36,11 @@ static void led_heartbeat_function(unsigned long data)
        unsigned long brightness = LED_OFF;
        unsigned long delay = 0;
 
+       if (unlikely(panic_heartbeats)) {
+               led_set_brightness(led_cdev, LED_OFF);
+               return;
+       }
+
        /* acts like an actual heart beat -- ie thump-thump-pause... */
        switch (heartbeat_data->phase) {
        case 0:

drivers/leds/ledtrig-heartbeat.c static int heartbeat_reboot_notifier(struct notifier_block *nb, · line 124

Quoted 7 lines
drivers/leds/ledtrig-heartbeat.c +4 -0
@@ -111,12 +118,19 @@ static int heartbeat_reboot_notifier(struct notifier_block *nb,
        return NOTIFY_DONE;
 }
 
+static int heartbeat_panic_notifier(struct notifier_block *nb,
+                                    unsigned long code, void *unused)
+{
+       panic_heartbeats = 1;

Can we just set LED as OFF and delete the timer here? because timer is also useless after a kernel panic.
So we don't need this global static variable here.

-Bryan

Quoted 16 lines
drivers/leds/ledtrig-heartbeat.c +4 -2
+       return NOTIFY_DONE;
+}
+
 static struct notifier_block heartbeat_reboot_nb = {
        .notifier_call = heartbeat_reboot_notifier,
 };
 
 static struct notifier_block heartbeat_panic_nb = {
-       .notifier_call = heartbeat_reboot_notifier,
+       .notifier_call = heartbeat_panic_notifier,
 };
 
 static int __init heartbeat_trig_init(void)
--

1.7.6.5

#4 lore raw

Re: [PATCH] leds: heartbeat: fix bug on panic

Am 04.07.2012 09:05, schrieb Bryan Wu:

Quoted 74 lines · Alexander Holler
Quoted 73 lines

With commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4 I introduced a bug (visible if CONFIG_PROVE_RCU is enabled) which occures when a panic has happened:

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal context switch in RCU read-side critical section!
[ 1526.520230]
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]
[ 1526.520230]
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>] do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>] panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>] rcu_lock_acquire+0x0/0x29
[ 1526.520230]
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>] __atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

So in case of a panic, now just turn of the LED. Other approaches like scheduling a work to unregister the trigger aren't working because there isn't much which still runs after a panic occured (except timers).

Signed-off-by Alexander Holler <[email protected]>
---
  drivers/leds/ledtrig-heartbeat.c |   16 +++++++++++++++-
  1 files changed, 15 insertions(+), 1 deletions(-)
drivers/leds/ledtrig-heartbeat.c +7 -0
index 41dc76d..a019fbb 100644
@@ -21,6 +21,8 @@
  #include <linux/reboot.h>
  #include "leds.h"
 
+static int panic_heartbeats;
+
  struct heartbeat_trig_data {
         unsigned int phase;
         unsigned int period;

@@ -34,6 +36,11 @@ static void led_heartbeat_function(unsigned long data)
         unsigned long brightness = LED_OFF;
         unsigned long delay = 0;
 
+       if (unlikely(panic_heartbeats)) {
+               led_set_brightness(led_cdev, LED_OFF);
+               return;
+       }
+
         /* acts like an actual heart beat -- ie thump-thump-pause... */
         switch (heartbeat_data->phase) {
         case 0:

@@ -111,12 +118,19 @@ static int heartbeat_reboot_notifier(struct notifier_block *nb,
         return NOTIFY_DONE;
  }
Quoted 8 lines

drivers/leds/ledtrig-heartbeat.c static int heartbeat_reboot_notifier(struct notifier_block *nb, · line 124

Quoted 4 lines
drivers/leds/ledtrig-heartbeat.c +4 -0
+static int heartbeat_panic_notifier(struct notifier_block *nb,
+                                    unsigned long code, void *unused)
+{
+       panic_heartbeats = 1;

Can we just set LED as OFF and delete the timer here? because timer is also useless after a kernel panic.
So we don't need this global static variable here.

No, the necessary information (heartbeat_trig_data) isn't available here.

Regards,

Alexander

#5 lore raw

Re: [PATCH] leds: heartbeat: fix bug on panic

Quoted 96 lines · Alexander Holler

Am 04.07.2012 09:05, schrieb Bryan Wu:

Quoted 83 lines
Quoted 81 lines · Alexander Holler

With commit 49dca5aebfdeadd4bf27b6cb4c60392147dc35a4 I introduced a bug (visible if CONFIG_PROVE_RCU is enabled) which occures when a panic has happened:

[ 1526.520230] ===============================
[ 1526.520230] [ INFO: suspicious RCU usage. ]
[ 1526.520230] 3.5.0-rc1+ #12 Not tainted
[ 1526.520230] -------------------------------
[ 1526.520230] /c/kernel-tests/mm/include/linux/rcupdate.h:436 Illegal
context switch in RCU read-side critical section!
[ 1526.520230]
[ 1526.520230] other info that might help us debug this:
[ 1526.520230]
[ 1526.520230]
[ 1526.520230] rcu_scheduler_active = 1, debug_locks = 0
[ 1526.520230] 3 locks held by net.agent/3279:
[ 1526.520230]  #0:  (&mm->mmap_sem){++++++}, at: [<ffffffff82f85962>]
do_page_fault+0x193/0x390
[ 1526.520230]  #1:  (panic_lock){+.+...}, at: [<ffffffff82ed2830>]
panic+0x37/0x1d3
[ 1526.520230]  #2:  (rcu_read_lock){.+.+..}, at: [<ffffffff810b9b28>]
rcu_lock_acquire+0x0/0x29
[ 1526.520230]
[ 1526.520230] stack backtrace:
[ 1526.520230] Pid: 3279, comm: net.agent Not tainted 3.5.0-rc1+ #12
[ 1526.520230] Call Trace:
[ 1526.520230]  [<ffffffff810e1570>] lockdep_rcu_suspicious+0x109/0x112
[ 1526.520230]  [<ffffffff810bfe3a>] rcu_preempt_sleep_check+0x45/0x47
[ 1526.520230]  [<ffffffff810bfe5a>] __might_sleep+0x1e/0x19a
[ 1526.520230]  [<ffffffff82f8010e>] down_write+0x26/0x81
[ 1526.520230]  [<ffffffff8276a966>] led_trigger_unregister+0x1f/0x9c
[ 1526.520230]  [<ffffffff8276def5>] heartbeat_reboot_notifier+0x15/0x19
[ 1526.520230]  [<ffffffff82f85bf5>] notifier_call_chain+0x96/0xcd
[ 1526.520230]  [<ffffffff82f85cba>]
__atomic_notifier_call_chain+0x8e/0xff
[ 1526.520230]  [<ffffffff81094b7c>] ? kmsg_dump+0x37/0x1eb
[ 1526.520230]  [<ffffffff82f85d3f>] atomic_notifier_call_chain+0x14/0x16
[ 1526.520230]  [<ffffffff82ed28e1>] panic+0xe8/0x1d3
[ 1526.520230]  [<ffffffff811473e2>] out_of_memory+0x15d/0x1d3

So in case of a panic, now just turn of the LED. Other approaches like scheduling a work to unregister the trigger aren't working because there isn't much which still runs after a panic occured (except timers).

Signed-off-by Alexander Holler <[email protected]>
---
  drivers/leds/ledtrig-heartbeat.c |   16 +++++++++++++++-
  1 files changed, 15 insertions(+), 1 deletions(-)
drivers/leds/ledtrig-heartbeat.c +7 -0
index 41dc76d..a019fbb 100644
@@ -21,6 +21,8 @@
  #include <linux/reboot.h>
  #include "leds.h"
 
+static int panic_heartbeats;
+
  struct heartbeat_trig_data {
         unsigned int phase;
         unsigned int period;

@@ -34,6 +36,11 @@ static void led_heartbeat_function(unsigned long data)
         unsigned long brightness = LED_OFF;
         unsigned long delay = 0;
 
+       if (unlikely(panic_heartbeats)) {
+               led_set_brightness(led_cdev, LED_OFF);
+               return;
+       }
+
         /* acts like an actual heart beat -- ie thump-thump-pause... */
         switch (heartbeat_data->phase) {
         case 0:

@@ -111,12 +118,19 @@ static int heartbeat_reboot_notifier(struct
 notifier_block *nb,
         return NOTIFY_DONE;
  }
Quoted 9 lines

drivers/leds/ledtrig-heartbeat.c static int heartbeat_reboot_notifier(struct notifier_block *nb, · line 124

Quoted 4 lines
drivers/leds/ledtrig-heartbeat.c +4 -0
+static int heartbeat_panic_notifier(struct notifier_block *nb,
+                                    unsigned long code, void *unused)
+{
+       panic_heartbeats = 1;

Can we just set LED as OFF and delete the timer here? because timer is also useless after a kernel panic.
So we don't need this global static variable here.

Quoted 2 lines

No, the necessary information (heartbeat_trig_data) isn't available here.

Yeah, looks like there is no way to pass heartbeat_trig_data information to the notifier call function.
Anyway, I will apply this patch to my for-next branch.

Thanks,

Signature · 4 lines
Bryan Wu <[email protected]>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com
#6 lore raw

Re: [PATCH] leds: heartbeat: fix bug on panic

Am 04.07.2012 09:29, schrieb Bryan Wu:

Quoted 1 line

Anyway, I will apply this patch to my for-next branch.

Is it already too late for 3.5 (where I introduced the bug)? I know I should have reacted faster, but I the bug report got down under a ton of other mails. ;)

Regards,

Alexander

#7 lore raw

Re: [PATCH] leds: heartbeat: fix bug on panic

Quoted 10 lines · Alexander Holler

Am 04.07.2012 09:29, schrieb Bryan Wu:

Quoted 1 line

Anyway, I will apply this patch to my for-next branch.

Is it already too late for 3.5 (where I introduced the bug)? I know I should have reacted faster, but I the bug report got down under a ton of other mails. ;)

OK, I will put it to my fixes-for-3.5 branch, since this is a real bug fixing.

Thanks,

Signature · 4 lines
Bryan Wu <[email protected]>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com