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From: Jinchao Wang <wangjinchao600@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Jinchao Wang <wangjinchao600@gmail.com>
Subject: [PATCH 2/3] perf/hw_breakpoint: Parse before reserving slots
Date: Wed,  3 Sep 2025 15:51:39 +0800	[thread overview]
Message-ID: <20250903075144.3722848-2-wangjinchao600@gmail.com> (raw)
In-Reply-To: <20250903075144.3722848-1-wangjinchao600@gmail.com>

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@gmail.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


  reply	other threads:[~2025-09-03  7:52 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-03  7:51 [PATCH 1/3] perf/hw_breakpoint: Optimize __modify_bp_slot() handling Jinchao Wang
2025-09-03  7:51 ` Jinchao Wang [this message]
2025-09-03  7:51 ` [PATCH 3/3] perf/hw_breakpoint: Skip modify_bp_slot() if slot index unchanged Jinchao Wang

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