Merge tag 'probes-fixes-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fixes from Masami Hiramatsu:

 - Return NULL if the trace_probe list on trace_probe_event is empty

 - selftests/ftrace: Choose testing symbol name for filtering feature
   from sample data instead of fixed symbol

* tag 'probes-fixes-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  selftests/ftrace: Choose target function for filter test from samples
  tracing/probe: trace_probe_primary_from_call(): checked list_first_entry

Author: torvalds

kernel/trace/trace_probe.h

@@ -308,7 +308,7 @@ trace_probe_primary_from_call(struct trace_event_call *call)
 {
 	struct trace_probe_event *tpe = trace_probe_event_from_call(call);
 
-	return list_first_entry(&tpe->probes, struct trace_probe, list);
+	return list_first_entry_or_null(&tpe->probes, struct trace_probe, list);
 }
 
 static inline struct list_head *trace_probe_probe_list(struct trace_probe *tp)

tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc

@@ -9,18 +9,33 @@ fail() { #msg
     exit_fail
 }
 
-echo "Test event filter function name"
+sample_events() {
+    echo > trace
+    echo 1 > events/kmem/kmem_cache_free/enable
+    echo 1 > tracing_on
+    ls > /dev/null
+    echo 0 > tracing_on
+    echo 0 > events/kmem/kmem_cache_free/enable
+}
+
 echo 0 > tracing_on
 echo 0 > events/enable
+
+echo "Get the most frequently calling function"
+sample_events
+
+target_func=`cut -d: -f3 trace | sed 's/call_site=\([^+]*\)+0x.*/\1/' | sort | uniq -c | sort | tail -n 1 | sed 's/^[ 0-9]*//'`
+if [ -z "$target_func" ]; then
+    exit_fail
+fi
 echo > trace
-echo 'call_site.function == exit_mmap' > events/kmem/kmem_cache_free/filter
-echo 1 > events/kmem/kmem_cache_free/enable
-echo 1 > tracing_on
-ls > /dev/null
-echo 0 > events/kmem/kmem_cache_free/enable
 
-hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
-misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+echo "Test event filter function name"
+echo "call_site.function == $target_func" > events/kmem/kmem_cache_free/filter
+sample_events
+
+hitcnt=`grep kmem_cache_free trace| grep $target_func | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v $target_func | wc -l`
 
 if [ $hitcnt -eq 0 ]; then
 	exit_fail
@@ -30,20 +45,14 @@ if [ $misscnt -gt 0 ]; then
 	exit_fail
 fi
 
-address=`grep ' exit_mmap$' /proc/kallsyms | cut -d' ' -f1`
+address=`grep " ${target_func}\$" /proc/kallsyms | cut -d' ' -f1`
 
 echo "Test event filter function address"
-echo 0 > tracing_on
-echo 0 > events/enable
-echo > trace
 echo "call_site.function == 0x$address" > events/kmem/kmem_cache_free/filter
-echo 1 > events/kmem/kmem_cache_free/enable
-echo 1 > tracing_on
-sleep 1
-echo 0 > events/kmem/kmem_cache_free/enable
+sample_events
 
-hitcnt=`grep kmem_cache_free trace| grep exit_mmap | wc -l`
-misscnt=`grep kmem_cache_free trace| grep -v exit_mmap | wc -l`
+hitcnt=`grep kmem_cache_free trace| grep $target_func | wc -l`
+misscnt=`grep kmem_cache_free trace| grep -v $target_func | wc -l`
 
 if [ $hitcnt -eq 0 ]; then
 	exit_fail