On Wed, Nov 26, 2014 at 1:14 AM, Kiran Raparthy <kiran.ku...@linaro.org> wrote:
> From: Colin Cross <ccr...@android.com>
>
> 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 <jason.wes...@windriver.com>
> Cc: kgdb-bugrep...@lists.sourceforge.net
> Cc: linux-kernel@vger.kernel.org
> Cc: Android Kernel Team <kernel-t...@android.com>
> Cc: John Stultz <john.stu...@linaro.org>
> Cc: Sumit Semwal <sumit.sem...@linaro.org>
> Signed-off-by: Colin Cross <ccr...@android.com>
> [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 <kiran.ku...@linaro.org>
> ---
> 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
>
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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?
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