linux-kernel - [PATCH 2/3] perf/hw_breakpoint: Parse before reserving slots

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Message-ID: <20250903075144.3722848-2-wangjinchao600@gmail.com>
Date: Wed,  3 Sep 2025 15:51:39 +0800
From: Jinchao Wang <wangjinchao600@...il.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	linux-perf-users@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Jinchao Wang <wangjinchao600@...il.com>
Subject: [PATCH 2/3] perf/hw_breakpoint: Parse before reserving slots

Reserve operations update global slot accounting across CPUs and are more
expensive than local parsing. Parsing only validates and decodes attributes
for the given breakpoint.

By moving parsing ahead of reserving, invalid attributes are rejected
before touching global state. This not only fails fast but also avoids
unnecessary reserve and release cycles.

Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
---
 kernel/events/hw_breakpoint.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 6066aff38eec..1db2c5e24d0e 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -706,15 +706,13 @@ int register_perf_hw_breakpoint(struct perf_event *bp)
 	struct arch_hw_breakpoint hw = { };
 	int err;
 
-	err = reserve_bp_slot(bp);
+	err = hw_breakpoint_parse(bp, &bp->attr, &hw);
 	if (err)
 		return err;
 
-	err = hw_breakpoint_parse(bp, &bp->attr, &hw);
-	if (err) {
-		release_bp_slot(bp);
+	err = reserve_bp_slot(bp);
+	if (err)
 		return err;
-	}
 
 	bp->hw.info = hw;
 
-- 
2.43.0