This is a note to let you know that I've just added the patch titled
tracing/boottime: Fix kprobe multiple events
to the 5.7-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-boottime-fix-kprobe-multiple-events.patch
and it can be found in the queue-5.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 20dc3847cc2fc886ee4eb9112e6e2fad9419b0c7 Mon Sep 17 00:00:00 2001
From: Sascha Ortmann <sascha.ortmann@xxxxxxxxxxxxxxxxxxxx>
Date: Thu, 18 Jun 2020 18:33:01 +0200
Subject: tracing/boottime: Fix kprobe multiple events
From: Sascha Ortmann <sascha.ortmann@xxxxxxxxxxxxxxxxxxxx>
commit 20dc3847cc2fc886ee4eb9112e6e2fad9419b0c7 upstream.
Fix boottime kprobe events to report and abort after each failure when
adding probes.
As an example, when we try to set multiprobe kprobe events in
bootconfig like this:
ftrace.event.kprobes.vfsevents {
probes = "vfs_read $arg1 $arg2,,
!error! not reported;?", // leads to error
"vfs_write $arg1 $arg2"
}
This will not work as expected. After
commit da0f1f4167e3af69e ("tracing/boottime: Fix kprobe event API usage"),
the function trace_boot_add_kprobe_event will not produce any error
message when adding a probe fails at kprobe_event_gen_cmd_start.
Furthermore, we continue to add probes when kprobe_event_gen_cmd_end fails
(and kprobe_event_gen_cmd_start did not fail). In this case the function
even returns successfully when the last call to kprobe_event_gen_cmd_end
is successful.
The behaviour of reporting and aborting after failures is not
consistent.
The function trace_boot_add_kprobe_event now reports each failure and
stops adding probes immediately.
Link: https://lkml.kernel.org/r/20200618163301.25854-1-sascha.ortmann@xxxxxxxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxx
Co-developed-by: Maximilian Werner <maximilian.werner96@xxxxxxxxx>
Fixes: da0f1f4167e3 ("tracing/boottime: Fix kprobe event API usage")
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Signed-off-by: Maximilian Werner <maximilian.werner96@xxxxxxxxx>
Signed-off-by: Sascha Ortmann <sascha.ortmann@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace_boot.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -101,12 +101,16 @@ trace_boot_add_kprobe_event(struct xbc_n
kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN);
ret = kprobe_event_gen_cmd_start(&cmd, event, val);
- if (ret)
+ if (ret) {
+ pr_err("Failed to generate probe: %s\n", buf);
break;
+ }
ret = kprobe_event_gen_cmd_end(&cmd);
- if (ret)
+ if (ret) {
pr_err("Failed to add probe: %s\n", buf);
+ break;
+ }
}
return ret;
Patches currently in stable-queue which might be from sascha.ortmann@xxxxxxxxxxxxxxxxxxxx are
queue-5.7/tracing-boottime-fix-kprobe-multiple-events.patch
