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authorFeng Tang <feng.tang@intel.com>2019-05-17 14:31:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-18 15:52:26 -0700
commitde6da1e8bcf0dd2058b950b127491821207679dc (patch)
tree2d54c823763d46cd070e5a721040bc1514df52ed /kernel
parent5d59aa8f9ce972b472201aed86e904bb75879ff0 (diff)
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panic: add an option to replay all the printk message in buffer
Currently on panic, kernel will lower the loglevel and print out pending printk msg only with console_flush_on_panic(). Add an option for users to configure the "panic_print" to replay all dmesg in buffer, some of which they may have never seen due to the loglevel setting, which will help panic debugging . [feng.tang@intel.com: keep the original console_flush_on_panic() inside panic()] Link: http://lkml.kernel.org/r/1556199137-14163-1-git-send-email-feng.tang@intel.com [feng.tang@intel.com: use logbuf lock to protect the console log index] Link: http://lkml.kernel.org/r/1556269868-22654-1-git-send-email-feng.tang@intel.com Link: http://lkml.kernel.org/r/1556095872-36838-1-git-send-email-feng.tang@intel.com Signed-off-by: Feng Tang <feng.tang@intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Aaro Koskinen <aaro.koskinen@nokia.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Borislav Petkov <bp@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/panic.c6
-rw-r--r--kernel/printk/printk.c12
2 files changed, 16 insertions, 2 deletions
diff --git a/kernel/panic.c b/kernel/panic.c
index 8779d64bace0..b4543a31a495 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -51,6 +51,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
#define PANIC_PRINT_TIMER_INFO 0x00000004
#define PANIC_PRINT_LOCK_INFO 0x00000008
#define PANIC_PRINT_FTRACE_INFO 0x00000010
+#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
unsigned long panic_print;
ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
@@ -134,6 +135,9 @@ EXPORT_SYMBOL(nmi_panic);
static void panic_print_sys_info(void)
{
+ if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
+ console_flush_on_panic(CONSOLE_REPLAY_ALL);
+
if (panic_print & PANIC_PRINT_TASK_INFO)
show_state();
@@ -277,7 +281,7 @@ void panic(const char *fmt, ...)
* panic() is not being callled from OOPS.
*/
debug_locks_off();
- console_flush_on_panic();
+ console_flush_on_panic(CONSOLE_FLUSH_PENDING);
panic_print_sys_info();
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 17102fd4c136..a6e06fe38e41 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2535,10 +2535,11 @@ void console_unblank(void)
/**
* console_flush_on_panic - flush console content on panic
+ * @mode: flush all messages in buffer or just the pending ones
*
* Immediately output all pending messages no matter what.
*/
-void console_flush_on_panic(void)
+void console_flush_on_panic(enum con_flush_mode mode)
{
/*
* If someone else is holding the console lock, trylock will fail
@@ -2549,6 +2550,15 @@ void console_flush_on_panic(void)
*/
console_trylock();
console_may_schedule = 0;
+
+ if (mode == CONSOLE_REPLAY_ALL) {
+ unsigned long flags;
+
+ logbuf_lock_irqsave(flags);
+ console_seq = log_first_seq;
+ console_idx = log_first_idx;
+ logbuf_unlock_irqrestore(flags);
+ }
console_unlock();
}