From: Namhyung Kim <namhyung@kernel.org>
Date: Fri, 30 Aug 2024 06:51:49 +0000 (-0700)
Subject: perf lock contention: Simplify spinlock check
X-Git-Tag: v6.12-rc1~109^2~75
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05a5dd1dfd8fdeee6498875c2d78d4385d627bd6;p=thirdparty%2Fkernel%2Fstable.git

perf lock contention: Simplify spinlock check

The LCB_F_SPIN bit is used for spinlock, rwlock and optimistic spinning
in mutex.  In get_tstamp_elem() it needs to check spinlock and rwlock
only.  As mutex sets the LCB_F_MUTEX, it can check those two bits and
reduce the number of operations.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20240830065150.1758962-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c
index e8a6f64630192..4b7237e178bd2 100644
--- a/tools/perf/util/bpf_skel/lock_contention.bpf.c
+++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c
@@ -323,8 +323,7 @@ static inline struct tstamp_data *get_tstamp_elem(__u32 flags)
 	struct tstamp_data *pelem;
 
 	/* Use per-cpu array map for spinlock and rwlock */
-	if (flags == (LCB_F_SPIN | LCB_F_READ) || flags == LCB_F_SPIN ||
-	    flags == (LCB_F_SPIN | LCB_F_WRITE)) {
+	if ((flags & (LCB_F_SPIN | LCB_F_MUTEX)) == LCB_F_SPIN) {
 		__u32 idx = 0;
 
 		pelem = bpf_map_lookup_elem(&tstamp_cpu, &idx);