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Subject[PATCH] tracing/kprobes: Simplify the logic of enable_trace_kprobe()

[ Note this is applied on top of the other patch to quiet gcc ]

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

The function enable_trace_kprobe() performs slightly differently if the file
parameter is passed in as NULL on non-NULL. Instead of checking file twice,
move the code between the two tests into a static inline helper function to
make the code easier to follow.

Link: http://lkml.kernel.org/r/20180725224728.7b1d5db2@vmware.local.home

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 42 ++++++++++++++++++++++++------------------
1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 6b71860f3998..1dec0855a59a 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -393,6 +393,20 @@ static struct trace_kprobe *find_trace_kprobe(const char *event,
return NULL;
}

+static inline int enable_probe(struct trace_kprobe *tk)
+{
+ int ret = 0;
+
+ if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
+ if (trace_kprobe_is_return(tk))
+ ret = enable_kretprobe(&tk->rp);
+ else
+ ret = enable_kprobe(&tk->rp.kp);
+ }
+
+ return ret;
+}
+
/*
* Enable trace_probe
* if the file is NULL, enable "perf" handler, or enable "trace" handler.
@@ -400,7 +414,7 @@ static struct trace_kprobe *find_trace_kprobe(const char *event,
static int
enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
{
- struct event_file_link *link = NULL;
+ struct event_file_link *link;
int ret = 0;

if (file) {
@@ -414,26 +428,18 @@ enable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file)
list_add_tail_rcu(&link->list, &tk->tp.files);

tk->tp.flags |= TP_FLAG_TRACE;
- } else
- tk->tp.flags |= TP_FLAG_PROFILE;
-
- if (trace_probe_is_registered(&tk->tp) && !trace_kprobe_has_gone(tk)) {
- if (trace_kprobe_is_return(tk))
- ret = enable_kretprobe(&tk->rp);
- else
- ret = enable_kprobe(&tk->rp.kp);
- }
-
- if (ret) {
- if (file) {
- /* Notice the if is true on not WARN() */
- if (!WARN_ON_ONCE(!link))
- list_del_rcu(&link->list);
+ ret = enable_probe(tk);
+ if (ret) {
+ list_del_rcu(&link->list);
kfree(link);
tk->tp.flags &= ~TP_FLAG_TRACE;
- } else {
- tk->tp.flags &= ~TP_FLAG_PROFILE;
}
+
+ } else {
+ tk->tp.flags |= TP_FLAG_PROFILE;
+ ret = enable_probe(tk);
+ if (ret)
+ tk->tp.flags &= ~TP_FLAG_PROFILE;
}
out:
return ret;
--
2.13.6
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