diff options
author | Vlastimil Babka <vbabka@suse.cz> | 2024-11-05 12:34:57 +0100 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2024-11-11 17:22:28 -0800 |
commit | 9b5c87d47949292ff21ee2fadd1e83820662a430 (patch) | |
tree | fda19b186ede122d39e2784814597b07729c23bd /mm/mmap_lock.c | |
parent | 9f3310ccc71efff041fed3f8be5ad19b0feab30b (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.c | 39 |
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(®_refcount); - return 0; -} - -void trace_mmap_lock_unreg(void) -{ - atomic_dec(®_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(®_refcount)) - return; memcg = get_mem_cgroup_from_mm(mm); if (memcg == NULL) return; |