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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/printk
parent5d59aa8f9ce972b472201aed86e904bb75879ff0 (diff)
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/printk')
-rw-r--r--kernel/printk/printk.c12
1 files changed, 11 insertions, 1 deletions
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();
}