On Wed, 17 Jun 2020 11:05:21 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Wed, 17 Jun 2020 16:08:17 +0200 > Sascha Ortmann <sascha.ortmann@xxxxxxxxxxxxxxxxxxxx> wrote: > > > Fix boottime kprobe events to add multiple events even if one fails > > and report probe generation failures. > > > > 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 like expected. After commit > > da0f1f4167e3af69e1d8b32d6d65195ddd2bfb64 ("tracing/boottime: > > Fix kprobe event API usage"), the function > > trace_boot_add_kprobe_event will not produce any error message, > > aborting the function and stopping subsequent probes from getting > > installed when adding a probe fails at kprobe_event_gen_cmd_start. > > Furthermore, probes continue 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 continues even when > > one of the multiple events fails. Each failure is now reported > > individually. Since the function can only return one result to the > > caller, the function returns now the last failure (or none, if > > nothing fails). > > > > Cc: linux-kernel@xxxxxxxxxxxx > > Signed-off-by: Maximilian Werner <maximilian.werner96@xxxxxxxxx> > > Signed-off-by: Sascha Ortmann <sascha.ortmann@xxxxxxxxxxxxxxxxxxxx> > > Why the double signed off by? > > Masami, I'm fine with this, but needs your review. [ It appears that Masami wasn't in the Cc ] > > -- Steve > > > --- > > kernel/trace/trace_boot.c | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c > > index 9de29bb45a27..dbb50184e060 100644 > > --- a/kernel/trace/trace_boot.c > > +++ b/kernel/trace/trace_boot.c > > @@ -95,18 +95,24 @@ trace_boot_add_kprobe_event(struct xbc_node *node, const char *event) > > struct xbc_node *anode; > > char buf[MAX_BUF_LEN]; > > const char *val; > > + int error = 0; > > int ret = 0; > > > > xbc_node_for_each_array_value(node, "probes", anode, val) { > > kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN); > > > > - ret = kprobe_event_gen_cmd_start(&cmd, event, val); > > - if (ret) > > - break; > > + error = kprobe_event_gen_cmd_start(&cmd, event, val); > > + if (error) { > > + pr_err("Failed to generate probe: %s\n", buf); > > + ret = error; > > + continue; > > + } > > > > - ret = kprobe_event_gen_cmd_end(&cmd); > > - if (ret) > > + error = kprobe_event_gen_cmd_end(&cmd); > > + if (error) { > > pr_err("Failed to add probe: %s\n", buf); > > + ret = error; > > + } > > } > > > > return ret; >