Patch "tracing: Fix tp_printk option related with tp_printk_stop_on_boot" has been added to the 4.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    tracing: Fix tp_printk option related with tp_printk_stop_on_boot

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tracing-fix-tp_printk-option-related-with-tp_printk_.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 839dbba17adc0258ab025722d0cfdf94e83893c8
Author: JaeSang Yoo <js.yoo.5b@xxxxxxxxx>
Date:   Wed Feb 9 04:54:22 2022 +0900

    tracing: Fix tp_printk option related with tp_printk_stop_on_boot
    
    [ Upstream commit 3203ce39ac0b2a57a84382ec184c7d4a0bede175 ]
    
    The kernel parameter "tp_printk_stop_on_boot" starts with "tp_printk" which is
    the same as another kernel parameter "tp_printk". If "tp_printk" setup is
    called before the "tp_printk_stop_on_boot", it will override the latter
    and keep it from being set.
    
    This is similar to other kernel parameter issues, such as:
      Commit 745a600cf1a6 ("um: console: Ignore console= option")
    or init/do_mounts.c:45 (setup function of "ro" kernel param)
    
    Fix it by checking for a "_" right after the "tp_printk" and if that
    exists do not process the parameter.
    
    Link: https://lkml.kernel.org/r/20220208195421.969326-1-jsyoo5b@xxxxxxxxx
    
    Signed-off-by: JaeSang Yoo <jsyoo5b@xxxxxxxxx>
    [ Fixed up change log and added space after if condition ]
    Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 01c646a1d9e76..12bee7043be6f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -228,6 +228,10 @@ __setup("trace_clock=", set_trace_boot_clock);
 
 static int __init set_tracepoint_printk(char *str)
 {
+	/* Ignore the "tp_printk_stop_on_boot" param */
+	if (*str == '_')
+		return 0;
+
 	if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0))
 		tracepoint_printk = 1;
 	return 1;