linux-kernel - [PATCH 5/5] perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify

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Date:   Mon, 27 Aug 2018 11:12:28 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Milind Chabbi <chabbi.milind@...il.com>,
        Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH 5/5] perf/hw_breakpoint: Simplify breakpoint enable in perf_event_modify_breakpoint

We can safely enable the breakpoint back for both the fail
and success paths by checking only the bp->attr.disabled,
which either holds the new 'requested' disabled state or
the original breakpoint state.

Suggested-by: Oleg Nesterov <oleg@...hat.com>
Acked-by: Oleg Nesterov <oleg@...hat.com>
Link: http://lkml.kernel.org/n/tip-vo1jm1u2nar6lj6hnd9g73ug@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 kernel/events/core.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index f6ea33a9f904..22ede28ec07d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2867,16 +2867,11 @@ static int perf_event_modify_breakpoint(struct perf_event *bp,
 	_perf_event_disable(bp);
 
 	err = modify_user_hw_breakpoint_check(bp, attr, true);
-	if (err) {
-		if (!bp->attr.disabled)
-			_perf_event_enable(bp);
 
-		return err;
-	}
-
-	if (!attr->disabled)
+	if (!bp->attr.disabled)
 		_perf_event_enable(bp);
-	return 0;
+
+	return err;
 }
 
 static int perf_event_modify_attr(struct perf_event *event,
-- 
2.17.1