[for-next][PATCH 04/11] tracing: Move open coded processing of tgid_map into helper function

Steven Rostedt
2024-02-21T14:06:40Z

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

In preparation of moving the saved_cmdlines logic out of trace.c and into
trace_sched_switch.c, replace the open coded manipulation of tgid_map in
set_tracer_flag() into a helper function trace_alloc_tgid_map() so that it
can be easily moved into trace_sched_switch.c without changing existing
functions in trace.c.

No functional changes.

Link: https://lore.kernel.org/linux-trace-kernel/20240220140703.338116216@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 38 +++++++++++++++++++++++---------------
1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 52faa30e64ed..06c593fc93d0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5432,10 +5432,31 @@ int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set)
return 0;
}

-int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
+static int trace_alloc_tgid_map(void)
{
int *map;

+ if (tgid_map)
+ return 0;
+
+ tgid_map_max = pid_max;
+ map = kvcalloc(tgid_map_max + 1, sizeof(*tgid_map),
+ GFP_KERNEL);
+ if (!map)
+ return -ENOMEM;
+
+ /*
+ * Pairs with smp_load_acquire() in
+ * trace_find_tgid_ptr() to ensure that if it observes
+ * the tgid_map we just allocated then it also observes
+ * the corresponding tgid_map_max value.
+ */
+ smp_store_release(&tgid_map, map);
+ return 0;
+}
+
+int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
+{
if ((mask == TRACE_ITER_RECORD_TGID) ||
(mask == TRACE_ITER_RECORD_CMD))
lockdep_assert_held(&event_mutex);
@@ -5458,20 +5479,7 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled)
trace_event_enable_cmd_record(enabled);

if (mask == TRACE_ITER_RECORD_TGID) {
- if (!tgid_map) {
- tgid_map_max = pid_max;
- map = kvcalloc(tgid_map_max + 1, sizeof(*tgid_map),
- GFP_KERNEL);
-
- /*
- * Pairs with smp_load_acquire() in
- * trace_find_tgid_ptr() to ensure that if it observes
- * the tgid_map we just allocated then it also observes
- * the corresponding tgid_map_max value.
- */
- smp_store_release(&tgid_map, map);
- }
- if (!tgid_map) {
+ if (trace_alloc_tgid_map() < 0) {
tr->trace_flags &= ~TRACE_ITER_RECORD_TGID;
return -ENOMEM;
}
--
2.43.0