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authorVlastimil Babka <vbabka@suse.cz>2024-11-05 12:34:57 +0100
committerAndrew Morton <akpm@linux-foundation.org>2024-11-11 17:22:28 -0800
commit9b5c87d47949292ff21ee2fadd1e83820662a430 (patch)
treefda19b186ede122d39e2784814597b07729c23bd /mm/mmap_lock.c
parent9f3310ccc71efff041fed3f8be5ad19b0feab30b (diff)
mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
Since 7d6be67cfdd4 ("mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer") we use trace_mmap_lock_reg()/unreg() only to maintain an atomic reg_refcount which is checked to avoid performing get_mm_memcg_path() in case none of the tracepoints using it is enabled. This can be achieved directly by putting all the work needed for the tracepoint behind the trace_mmap_lock_##type##_enabled(), as suggested by Documentation/trace/tracepoints.rst and with the following advantages: - uses the tracepoint's static key instead of evaluating a branch - the check tracepoint specific, not shared by all of them - we can get rid of trace_mmap_lock_reg()/unreg() completely Thus use the trace_..._enabled() check and remove unnecessary code. Link: https://lkml.kernel.org/r/20241105113456.95066-2-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Axel Rasmussen <axelrasmussen@google.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mmap_lock.c')
-rw-r--r--mm/mmap_lock.c39
1 files changed, 8 insertions, 31 deletions
diff --git a/mm/mmap_lock.c b/mm/mmap_lock.c
index 368b840e7508..f186d57df2c6 100644
--- a/mm/mmap_lock.c
+++ b/mm/mmap_lock.c
@@ -19,43 +19,23 @@ EXPORT_TRACEPOINT_SYMBOL(mmap_lock_released);
#ifdef CONFIG_MEMCG
-static atomic_t reg_refcount;
-
/*
* Size of the buffer for memcg path names. Ignoring stack trace support,
* trace_events_hist.c uses MAX_FILTER_STR_VAL for this, so we also use it.
*/
#define MEMCG_PATH_BUF_SIZE MAX_FILTER_STR_VAL
-int trace_mmap_lock_reg(void)
-{
- atomic_inc(&reg_refcount);
- return 0;
-}
-
-void trace_mmap_lock_unreg(void)
-{
- atomic_dec(&reg_refcount);
-}
-
-#define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \
- do { \
- char buf[MEMCG_PATH_BUF_SIZE]; \
- get_mm_memcg_path(mm, buf, sizeof(buf)); \
- trace_mmap_lock_##type(mm, buf, ##__VA_ARGS__); \
+#define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \
+ do { \
+ if (trace_mmap_lock_##type##_enabled()) { \
+ char buf[MEMCG_PATH_BUF_SIZE]; \
+ get_mm_memcg_path(mm, buf, sizeof(buf)); \
+ trace_mmap_lock_##type(mm, buf, ##__VA_ARGS__); \
+ } \
} while (0)
#else /* !CONFIG_MEMCG */
-int trace_mmap_lock_reg(void)
-{
- return 0;
-}
-
-void trace_mmap_lock_unreg(void)
-{
-}
-
#define TRACE_MMAP_LOCK_EVENT(type, mm, ...) \
trace_mmap_lock_##type(mm, "", ##__VA_ARGS__)
@@ -65,16 +45,13 @@ void trace_mmap_lock_unreg(void)
#ifdef CONFIG_MEMCG
/*
* Write the given mm_struct's memcg path to a buffer. If the path cannot be
- * determined or the trace event is being unregistered, empty string is written.
+ * determined, empty string is written.
*/
static void get_mm_memcg_path(struct mm_struct *mm, char *buf, size_t buflen)
{
struct mem_cgroup *memcg;
buf[0] = '\0';
- /* No need to get path if no trace event is registered. */
- if (!atomic_read(&reg_refcount))
- return;
memcg = get_mem_cgroup_from_mm(mm);
if (memcg == NULL)
return;