From: Colin Cross <[email protected]>
debug: prevent entering debug mode on errors
On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
device after a panic.
In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
entering debug mode to avoid getting stuck waiting for the user to interact
with debugger.
Cc: Jason Wessel <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Android Kernel Team <[email protected]>
Cc: John Stultz <[email protected]>
Cc: Sumit Semwal <[email protected]>
Signed-off-by: Colin Cross <[email protected]>
[Kiran: Added context to commit message.
panic_timeout is used instead of break_on_panic and
break_on_exception to honor CONFIG_PANIC_TIMEOUT]
Signed-off-by: Kiran Raparthy <[email protected]>
---
kernel/debug/debug_core.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 1adf62b..0012a1f 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
if (arch_kgdb_ops.enable_nmi)
arch_kgdb_ops.enable_nmi(0);
+ /*
+ * Avoid entering the debugger if we were triggered due to an oops
+ * but panic_timeout indicates the system should automatically
+ * reboot on panic. We don't want to get stuck waiting for input
+ * on such systems, especially if its "just" an oops.
+ */
+ if (signo != SIGTRAP && panic_timeout)
+ return 1;
memset(ks, 0, sizeof(struct kgdb_state));
ks->cpu = raw_smp_processor_id();
@@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
unsigned long val,
void *data)
{
+ /*
+ * Avoid entering the debugger if we were triggered due to a panic
+ * We don't want to get stuck waiting for input from user in such case.
+ * panic_timeout indicates the system should automatically
+ * reboot on panic.
+ */
+ if (panic_timeout)
+ return NOTIFY_DONE;
+
if (dbg_kdb_mode)
kdb_printf("PANIC: %s\n", (char *)data);
kgdb_breakpoint();
--
1.8.2.1
On 26/11/14 09:14, Kiran Raparthy wrote:
> From: Colin Cross <[email protected]>
>
> debug: prevent entering debug mode on errors
>
> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
> device after a panic.
>
> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
> entering debug mode to avoid getting stuck waiting for the user to interact
> with debugger.
>
> Cc: Jason Wessel <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: Android Kernel Team <[email protected]>
> Cc: John Stultz <[email protected]>
> Cc: Sumit Semwal <[email protected]>
> Signed-off-by: Colin Cross <[email protected]>
> [Kiran: Added context to commit message.
> panic_timeout is used instead of break_on_panic and
> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
> Signed-off-by: Kiran Raparthy <[email protected]>
When this gets upgrade from RFC to PATCH then feel free to add:
Reviewed-by: Daniel Thompson <[email protected]>
> ---
> kernel/debug/debug_core.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
> index 1adf62b..0012a1f 100644
> --- a/kernel/debug/debug_core.c
> +++ b/kernel/debug/debug_core.c
> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>
> if (arch_kgdb_ops.enable_nmi)
> arch_kgdb_ops.enable_nmi(0);
> + /*
> + * Avoid entering the debugger if we were triggered due to an oops
> + * but panic_timeout indicates the system should automatically
> + * reboot on panic. We don't want to get stuck waiting for input
> + * on such systems, especially if its "just" an oops.
> + */
> + if (signo != SIGTRAP && panic_timeout)
> + return 1;
>
> memset(ks, 0, sizeof(struct kgdb_state));
> ks->cpu = raw_smp_processor_id();
> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
> unsigned long val,
> void *data)
> {
> + /*
> + * Avoid entering the debugger if we were triggered due to a panic
> + * We don't want to get stuck waiting for input from user in such case.
> + * panic_timeout indicates the system should automatically
> + * reboot on panic.
> + */
> + if (panic_timeout)
> + return NOTIFY_DONE;
> +
> if (dbg_kdb_mode)
> kdb_printf("PANIC: %s\n", (char *)data);
> kgdb_breakpoint();
>
On 26 November 2014 at 14:56, Daniel Thompson
<[email protected]> wrote:
> On 26/11/14 09:14, Kiran Raparthy wrote:
>> From: Colin Cross <[email protected]>
>>
>> debug: prevent entering debug mode on errors
>>
>> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
>> device after a panic.
>>
>> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
>> entering debug mode to avoid getting stuck waiting for the user to interact
>> with debugger.
>>
>> Cc: Jason Wessel <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: Android Kernel Team <[email protected]>
>> Cc: John Stultz <[email protected]>
>> Cc: Sumit Semwal <[email protected]>
>> Signed-off-by: Colin Cross <[email protected]>
>> [Kiran: Added context to commit message.
>> panic_timeout is used instead of break_on_panic and
>> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
>> Signed-off-by: Kiran Raparthy <[email protected]>
>
> When this gets upgrade from RFC to PATCH then feel free to add:
> Reviewed-by: Daniel Thompson <[email protected]>
Sure.
Regards,
Kiran
>
>> ---
>> kernel/debug/debug_core.c | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
>> index 1adf62b..0012a1f 100644
>> --- a/kernel/debug/debug_core.c
>> +++ b/kernel/debug/debug_core.c
>> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>>
>> if (arch_kgdb_ops.enable_nmi)
>> arch_kgdb_ops.enable_nmi(0);
>> + /*
>> + * Avoid entering the debugger if we were triggered due to an oops
>> + * but panic_timeout indicates the system should automatically
>> + * reboot on panic. We don't want to get stuck waiting for input
>> + * on such systems, especially if its "just" an oops.
>> + */
>> + if (signo != SIGTRAP && panic_timeout)
>> + return 1;
>>
>> memset(ks, 0, sizeof(struct kgdb_state));
>> ks->cpu = raw_smp_processor_id();
>> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
>> unsigned long val,
>> void *data)
>> {
>> + /*
>> + * Avoid entering the debugger if we were triggered due to a panic
>> + * We don't want to get stuck waiting for input from user in such case.
>> + * panic_timeout indicates the system should automatically
>> + * reboot on panic.
>> + */
>> + if (panic_timeout)
>> + return NOTIFY_DONE;
>> +
>> if (dbg_kdb_mode)
>> kdb_printf("PANIC: %s\n", (char *)data);
>> kgdb_breakpoint();
>>
>
On Wed, Nov 26, 2014 at 1:14 AM, Kiran Raparthy <[email protected]> wrote:
> From: Colin Cross <[email protected]>
>
> debug: prevent entering debug mode on errors
>
> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
> device after a panic.
>
> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
> entering debug mode to avoid getting stuck waiting for the user to interact
> with debugger.
>
> Cc: Jason Wessel <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: Android Kernel Team <[email protected]>
> Cc: John Stultz <[email protected]>
> Cc: Sumit Semwal <[email protected]>
> Signed-off-by: Colin Cross <[email protected]>
> [Kiran: Added context to commit message.
> panic_timeout is used instead of break_on_panic and
> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
> Signed-off-by: Kiran Raparthy <[email protected]>
> ---
> kernel/debug/debug_core.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
> index 1adf62b..0012a1f 100644
> --- a/kernel/debug/debug_core.c
> +++ b/kernel/debug/debug_core.c
> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>
> if (arch_kgdb_ops.enable_nmi)
> arch_kgdb_ops.enable_nmi(0);
> + /*
> + * Avoid entering the debugger if we were triggered due to an oops
> + * but panic_timeout indicates the system should automatically
> + * reboot on panic. We don't want to get stuck waiting for input
> + * on such systems, especially if its "just" an oops.
> + */
> + if (signo != SIGTRAP && panic_timeout)
> + return 1;
>
> memset(ks, 0, sizeof(struct kgdb_state));
> ks->cpu = raw_smp_processor_id();
> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
> unsigned long val,
> void *data)
> {
> + /*
> + * Avoid entering the debugger if we were triggered due to a panic
> + * We don't want to get stuck waiting for input from user in such case.
> + * panic_timeout indicates the system should automatically
> + * reboot on panic.
> + */
> + if (panic_timeout)
> + return NOTIFY_DONE;
> +
> if (dbg_kdb_mode)
> kdb_printf("PANIC: %s\n", (char *)data);
> kgdb_breakpoint();
> --
> 1.8.2.1
>
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
The original patch was more useful as it allowed re-enabling break on
panic on specific devices where you were trying to debug a
reproducible issue. What about using a module_param similar to
kgdbreboot, but setting the default based on CONFIG_PANIC_TIMEOUT to
avoid extra configuration?
On 26/11/14 17:45, Colin Cross wrote:
> On Wed, Nov 26, 2014 at 1:14 AM, Kiran Raparthy <[email protected]> wrote:
>> From: Colin Cross <[email protected]>
>>
>> debug: prevent entering debug mode on errors
>>
>> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
>> device after a panic.
>>
>> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
>> entering debug mode to avoid getting stuck waiting for the user to interact
>> with debugger.
>>
>> Cc: Jason Wessel <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Cc: Android Kernel Team <[email protected]>
>> Cc: John Stultz <[email protected]>
>> Cc: Sumit Semwal <[email protected]>
>> Signed-off-by: Colin Cross <[email protected]>
>> [Kiran: Added context to commit message.
>> panic_timeout is used instead of break_on_panic and
>> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
>> Signed-off-by: Kiran Raparthy <[email protected]>
>> ---
>> kernel/debug/debug_core.c | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
>> index 1adf62b..0012a1f 100644
>> --- a/kernel/debug/debug_core.c
>> +++ b/kernel/debug/debug_core.c
>> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>>
>> if (arch_kgdb_ops.enable_nmi)
>> arch_kgdb_ops.enable_nmi(0);
>> + /*
>> + * Avoid entering the debugger if we were triggered due to an oops
>> + * but panic_timeout indicates the system should automatically
>> + * reboot on panic. We don't want to get stuck waiting for input
>> + * on such systems, especially if its "just" an oops.
>> + */
>> + if (signo != SIGTRAP && panic_timeout)
>> + return 1;
>>
>> memset(ks, 0, sizeof(struct kgdb_state));
>> ks->cpu = raw_smp_processor_id();
>> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
>> unsigned long val,
>> void *data)
>> {
>> + /*
>> + * Avoid entering the debugger if we were triggered due to a panic
>> + * We don't want to get stuck waiting for input from user in such case.
>> + * panic_timeout indicates the system should automatically
>> + * reboot on panic.
>> + */
>> + if (panic_timeout)
>> + return NOTIFY_DONE;
>> +
>> if (dbg_kdb_mode)
>> kdb_printf("PANIC: %s\n", (char *)data);
>> kgdb_breakpoint();
>
> The original patch was more useful as it allowed re-enabling break on
> panic on specific devices where you were trying to debug a
> reproducible issue. What about using a module_param similar to
> kgdbreboot, but setting the default based on CONFIG_PANIC_TIMEOUT to
> avoid extra configuration?
This change was due to my review so perhaps I'd better answer this...
panic_timeout is the value of the panic sysctl. In addition to the
normal sysctl tooling (which I don't think is available on most android
systems), its value can be set using panic=0 on the kernel command line
or via /proc/sys/kernel/panic at runtime.
CONFIG_PANIC_TIMEOUT merely sets the default value of the sysctl. I
guess perhaps the patch description could be improved to make this clearer.
Therefore, the only loss of function I expected versus the original is
that it would be hard to get as far as a reproducible panic if the
system also has a ton of reproducible oopses that we don't want to fix.
Is such a use-case important?
Hi Jason,
On 27 November 2014 at 15:19, Daniel Thompson
<[email protected]> wrote:
> On 26/11/14 17:45, Colin Cross wrote:
>> On Wed, Nov 26, 2014 at 1:14 AM, Kiran Raparthy <[email protected]> wrote:
>>> From: Colin Cross <[email protected]>
>>>
>>> debug: prevent entering debug mode on errors
>>>
>>> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
>>> device after a panic.
>>>
>>> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
>>> entering debug mode to avoid getting stuck waiting for the user to interact
>>> with debugger.
>>>
>>> Cc: Jason Wessel <[email protected]>
>>> Cc: [email protected]
>>> Cc: [email protected]
>>> Cc: Android Kernel Team <[email protected]>
>>> Cc: John Stultz <[email protected]>
>>> Cc: Sumit Semwal <[email protected]>
>>> Signed-off-by: Colin Cross <[email protected]>
>>> [Kiran: Added context to commit message.
>>> panic_timeout is used instead of break_on_panic and
>>> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
>>> Signed-off-by: Kiran Raparthy <[email protected]>
>>> ---
>>> kernel/debug/debug_core.c | 17 +++++++++++++++++
>>> 1 file changed, 17 insertions(+)
>>>
>>> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
>>> index 1adf62b..0012a1f 100644
>>> --- a/kernel/debug/debug_core.c
>>> +++ b/kernel/debug/debug_core.c
>>> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>>>
>>> if (arch_kgdb_ops.enable_nmi)
>>> arch_kgdb_ops.enable_nmi(0);
>>> + /*
>>> + * Avoid entering the debugger if we were triggered due to an oops
>>> + * but panic_timeout indicates the system should automatically
>>> + * reboot on panic. We don't want to get stuck waiting for input
>>> + * on such systems, especially if its "just" an oops.
>>> + */
>>> + if (signo != SIGTRAP && panic_timeout)
>>> + return 1;
>>>
>>> memset(ks, 0, sizeof(struct kgdb_state));
>>> ks->cpu = raw_smp_processor_id();
>>> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
>>> unsigned long val,
>>> void *data)
>>> {
>>> + /*
>>> + * Avoid entering the debugger if we were triggered due to a panic
>>> + * We don't want to get stuck waiting for input from user in such case.
>>> + * panic_timeout indicates the system should automatically
>>> + * reboot on panic.
>>> + */
>>> + if (panic_timeout)
>>> + return NOTIFY_DONE;
>>> +
>>> if (dbg_kdb_mode)
>>> kdb_printf("PANIC: %s\n", (char *)data);
>>> kgdb_breakpoint();
>>
>> The original patch was more useful as it allowed re-enabling break on
>> panic on specific devices where you were trying to debug a
>> reproducible issue. What about using a module_param similar to
>> kgdbreboot, but setting the default based on CONFIG_PANIC_TIMEOUT to
>> avoid extra configuration?
>
> This change was due to my review so perhaps I'd better answer this...
>
> panic_timeout is the value of the panic sysctl. In addition to the
> normal sysctl tooling (which I don't think is available on most android
> systems), its value can be set using panic=0 on the kernel command line
> or via /proc/sys/kernel/panic at runtime.
>
> CONFIG_PANIC_TIMEOUT merely sets the default value of the sysctl. I
> guess perhaps the patch description could be improved to make this clearer.
>
> Therefore, the only loss of function I expected versus the original is
> that it would be hard to get as far as a reproducible panic if the
> system also has a ton of reproducible oopses that we don't want to fix.
> Is such a use-case important?
Could you please let me know if this patch is good to move from RFC to PATCH?
Regards,
Kiran
On Thu, Nov 27, 2014 at 1:49 AM, Daniel Thompson
<[email protected]> wrote:
> On 26/11/14 17:45, Colin Cross wrote:
>> The original patch was more useful as it allowed re-enabling break on
>> panic on specific devices where you were trying to debug a
>> reproducible issue. What about using a module_param similar to
>> kgdbreboot, but setting the default based on CONFIG_PANIC_TIMEOUT to
>> avoid extra configuration?
>
> This change was due to my review so perhaps I'd better answer this...
>
> panic_timeout is the value of the panic sysctl. In addition to the
> normal sysctl tooling (which I don't think is available on most android
> systems), its value can be set using panic=0 on the kernel command line
> or via /proc/sys/kernel/panic at runtime.
>
> CONFIG_PANIC_TIMEOUT merely sets the default value of the sysctl. I
> guess perhaps the patch description could be improved to make this clearer.
>
> Therefore, the only loss of function I expected versus the original is
> that it would be hard to get as far as a reproducible panic if the
> system also has a ton of reproducible oopses that we don't want to fix.
> Is such a use-case important?
OK, works for me.
Hi Jason,
On 1 December 2014 at 11:32, Kiran Raparthy <[email protected]> wrote:
> Hi Jason,
>
> On 27 November 2014 at 15:19, Daniel Thompson
> <[email protected]> wrote:
>> On 26/11/14 17:45, Colin Cross wrote:
>>> On Wed, Nov 26, 2014 at 1:14 AM, Kiran Raparthy <[email protected]> wrote:
>>>> From: Colin Cross <[email protected]>
>>>>
>>>> debug: prevent entering debug mode on errors
>>>>
>>>> On non-developer devices kgdb prevents CONFIG_PANIC_TIMEOUT from rebooting the
>>>> device after a panic.
>>>>
>>>> In case of panics and exceptions, to honor CONFIG_PANIC_TIMEOUT, prevent
>>>> entering debug mode to avoid getting stuck waiting for the user to interact
>>>> with debugger.
>>>>
>>>> Cc: Jason Wessel <[email protected]>
>>>> Cc: [email protected]
>>>> Cc: [email protected]
>>>> Cc: Android Kernel Team <[email protected]>
>>>> Cc: John Stultz <[email protected]>
>>>> Cc: Sumit Semwal <[email protected]>
>>>> Signed-off-by: Colin Cross <[email protected]>
>>>> [Kiran: Added context to commit message.
>>>> panic_timeout is used instead of break_on_panic and
>>>> break_on_exception to honor CONFIG_PANIC_TIMEOUT]
>>>> Signed-off-by: Kiran Raparthy <[email protected]>
>>>> ---
>>>> kernel/debug/debug_core.c | 17 +++++++++++++++++
>>>> 1 file changed, 17 insertions(+)
>>>>
>>>> diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
>>>> index 1adf62b..0012a1f 100644
>>>> --- a/kernel/debug/debug_core.c
>>>> +++ b/kernel/debug/debug_core.c
>>>> @@ -689,6 +689,14 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
>>>>
>>>> if (arch_kgdb_ops.enable_nmi)
>>>> arch_kgdb_ops.enable_nmi(0);
>>>> + /*
>>>> + * Avoid entering the debugger if we were triggered due to an oops
>>>> + * but panic_timeout indicates the system should automatically
>>>> + * reboot on panic. We don't want to get stuck waiting for input
>>>> + * on such systems, especially if its "just" an oops.
>>>> + */
>>>> + if (signo != SIGTRAP && panic_timeout)
>>>> + return 1;
>>>>
>>>> memset(ks, 0, sizeof(struct kgdb_state));
>>>> ks->cpu = raw_smp_processor_id();
>>>> @@ -821,6 +829,15 @@ static int kgdb_panic_event(struct notifier_block *self,
>>>> unsigned long val,
>>>> void *data)
>>>> {
>>>> + /*
>>>> + * Avoid entering the debugger if we were triggered due to a panic
>>>> + * We don't want to get stuck waiting for input from user in such case.
>>>> + * panic_timeout indicates the system should automatically
>>>> + * reboot on panic.
>>>> + */
>>>> + if (panic_timeout)
>>>> + return NOTIFY_DONE;
>>>> +
>>>> if (dbg_kdb_mode)
>>>> kdb_printf("PANIC: %s\n", (char *)data);
>>>> kgdb_breakpoint();
>>>
>>> The original patch was more useful as it allowed re-enabling break on
>>> panic on specific devices where you were trying to debug a
>>> reproducible issue. What about using a module_param similar to
>>> kgdbreboot, but setting the default based on CONFIG_PANIC_TIMEOUT to
>>> avoid extra configuration?
>>
>> This change was due to my review so perhaps I'd better answer this...
>>
>> panic_timeout is the value of the panic sysctl. In addition to the
>> normal sysctl tooling (which I don't think is available on most android
>> systems), its value can be set using panic=0 on the kernel command line
>> or via /proc/sys/kernel/panic at runtime.
>>
>> CONFIG_PANIC_TIMEOUT merely sets the default value of the sysctl. I
>> guess perhaps the patch description could be improved to make this clearer.
>>
>> Therefore, the only loss of function I expected versus the original is
>> that it would be hard to get as far as a reproducible panic if the
>> system also has a ton of reproducible oopses that we don't want to fix.
>> Is such a use-case important?
>
> Could you please let me know if this patch is good to move from RFC to PATCH?
Just a gentle reminder.
Regards,
Kiran
> Regards,
> Kiran