From: Sascha Ortmann sascha.ortmann@stud.uni-hannover.de
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@stud.uni-han...
Cc: stable@vger.kernel.org Cc: linux-kernel@i4.cs.fau.de Co-developed-by: Maximilian Werner maximilian.werner96@gmail.com Fixes: da0f1f4167e3 ("tracing/boottime: Fix kprobe event API usage") Acked-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Maximilian Werner maximilian.werner96@gmail.com Signed-off-by: Sascha Ortmann sascha.ortmann@stud.uni-hannover.de Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/trace/trace_boot.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c index 9de29bb45a27f..fdc5abc00bf84 100644 --- a/kernel/trace/trace_boot.c +++ b/kernel/trace/trace_boot.c @@ -101,12 +101,16 @@ trace_boot_add_kprobe_event(struct xbc_node *node, const char *event) 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;