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SubjectRe: [PATCH v2] panic: add an option to replay all the printk message in buffer
On (04/18/19 09:45), Petr Mladek wrote:
> The following functions are currently called from panic_print_sys_info():
>
> + show_state():
> printk(KERN_INFO
> " task PC stack pid father\n");
> + show_mem():
> printk("Mem-Info:\n");
>
> + sysrq_timer_list_show()
> no global header; but each section can be easily distinguished
> because there are several static strings that explains the
> content
>
> + debug_show_all_locks()
> pr_warn("\nShowing all locks held in the system:\n");
>
> + ftrace_dump():
> printk(KERN_TRACE "Dumping ftrace buffer:\n");

Oh, thanks.

> The person that enabled the debugging option might know what it did
> when it process the log the very same day. It might be less clear
> for others reading the log.
>
> Also it still might be convenient to find the beginning easily.
> Or it might help to orientate when several test runs
> (over night test) are squashed in a single file. I see
> such logs pretty often.

OK, well since we are talking here about serial log, then we probably
can just add printk("dump logbuf:\n"). It will appear before the
FLUSH_ALL output. Or we can just tweak panic code a bit - anything
panic_print_sys_info() prints can be "after" end of panic marker.

Basically, just move pr_emerg("---[ end Kernel panic...") a bit. I don't
quite understand why is it at the bottom - we don't always print end of
panic maker, e.g. when panic_timeout != 0. Not sure if this was
intentional.

---
diff --git a/kernel/panic.c b/kernel/panic.c
index 50eacfc9bc7e..1940a142c26e 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -282,6 +282,7 @@ void panic(const char *fmt, ...)
*/
debug_locks_off();
console_flush_on_panic(CONSOLE_FLUSH_PENDING);
+ pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);

panic_print_sys_info();

@@ -331,7 +332,6 @@ void panic(const char *fmt, ...)
disabled_wait(caller);
}
#endif
- pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);

/* Do not scroll important messages printed above */
suppress_printk = 1;
---
-ss

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