Messages in this thread | | | Date | Sat, 25 Apr 2020 10:00:20 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 2/3] tracing/boottime: Fix kprobe event API usage |
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On Sat, 25 Apr 2020 14:49:17 +0900 Masami Hiramatsu <mhiramat@kernel.org> wrote:
> Fix boottime kprobe events to use API correctly for > multiple events. > > For example, when we set a multiprobe kprobe events in > bootconfig like below, > > ftrace.event.kprobes.myevent { > probes = "vfs_read $arg1 $arg2", "vfs_write $arg1 $arg2" > } > > This cause an error; > > trace_boot: Failed to add probe: p:kprobes/myevent (null) vfs_read $arg1 $arg2 vfs_write $arg1 $arg2 > > This shows the 1st argument becomes NULL and multiprobes > are merged to 1 probe. > > Fixes: 29a154810546 ("tracing: Change trace_boot to use kprobe_event interface") > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > Cc: stable@vger.kernel.org > --- > kernel/trace/trace_boot.c | 20 ++++++++------------ > 1 file changed, 8 insertions(+), 12 deletions(-) > > diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c > index 06d7feb5255f..9de29bb45a27 100644 > --- a/kernel/trace/trace_boot.c > +++ b/kernel/trace/trace_boot.c > @@ -95,24 +95,20 @@ 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 ret; > + int ret = 0; > > - kprobe_event_cmd_init(&cmd, buf, MAX_BUF_LEN); > + 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, NULL); > - if (ret) > - return ret; > + ret = kprobe_event_gen_cmd_start(&cmd, event, val); > + if (ret) > + break;
Should we break here? What about just printing an error message and continuing to the next probe. If I start up something with a typo in the first element, I lose all events. But if I have a typo in the last one, I get all but that one. I rather have it just fail on the ones that don't parse properly.
-- Steve
> > - xbc_node_for_each_array_value(node, "probes", anode, val) { > - ret = kprobe_event_add_field(&cmd, val); > + ret = kprobe_event_gen_cmd_end(&cmd); > if (ret) > - return ret; > + pr_err("Failed to add probe: %s\n", buf); > } > > - ret = kprobe_event_gen_cmd_end(&cmd); > - if (ret) > - pr_err("Failed to add probe: %s\n", buf); > - > return ret; > } > #else
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