Commit bde1e7d9 authored Jun 02, 2021 by Leo Yan Committed by Arnaldo Carvalho de Melo Jun 08, 2021

perf auxtrace: Change to use SMP memory barriers



The kernel and the userspace tool can access the AUX ring buffer head
and tail from different CPUs, thus SMP class of barriers are required
on SMP system.

This patch changes to use SMP barriers to replace mb() and rmb()
barriers.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/20210602103007.184993-6-leo.yan@linaro.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent f54cad25

tools/perf/util/auxtrace.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -452,7 +452,7 @@ static inline u64 auxtrace_mmap__read_snapshot_head(struct auxtrace_mmap *mm)
		u64 head = READ_ONCE(pc->aux_head);

		/* Ensure all reads are done after we read the head */
		rmb();
		smp_rmb();
		return head;
		}

		@@ -466,7 +466,7 @@ static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
		#endif

		/* Ensure all reads are done after we read the head */
		rmb();
		smp_rmb();
		return head;
		}

		@@ -478,7 +478,7 @@ static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
		#endif

		/* Ensure all reads are done before we write the tail out */
		mb();
		smp_mb();
		#if BITS_PER_LONG == 64 \|\| !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
		pc->aux_tail = tail;
		#else