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authorColin Cross <ccross@android.com>2015-01-28 17:02:14 +0530
committerDaniel Thompson <daniel.thompson@linaro.org>2015-02-06 11:21:13 +0000
commit257eaf8518a832f3b4947a8d62bf027943545d78 (patch)
tree4b20fcfd0ba76c9b970150caf86ea7beb5268f4c
parent38a91aa23ef75e36be9e645da4572f6af439685a (diff)
downloadlinux-257eaf8518a832f3b4947a8d62bf027943545d78.tar.gz
debug: prevent entering debug mode on panic/exception.for_jason-3.20merge/for_jason-3.20
On non-developer devices, kgdb prevents the device from rebooting after a panic. Incase of panics and exceptions, to allow the device to reboot, prevent entering debug mode to avoid getting stuck waiting for the user to interact with debugger. To avoid entering the debugger on panic/exception without any extra configuration, panic_timeout is being used which can be set via /proc/sys/kernel/panic at run time and CONFIG_PANIC_TIMEOUT sets the default value. Setting panic_timeout indicates that the user requested machine to perform unattended reboot after panic. We dont want to get stuck waiting for the user input incase of panic. Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: kgdb-bugreport@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org Cc: Android Kernel Team <kernel-team@android.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Signed-off-by: Colin Cross <ccross@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 Modified the commit as per community feedback] Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
-rw-r--r--kernel/debug/debug_core.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 07ce18ca71e0..3db4fe6795e3 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -696,6 +696,14 @@ 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();
@@ -828,6 +836,15 @@ 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();