linux-kernel - [PATCH V3 14/25] perf/x86: Remove temporary pmu assignment in event

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Message-Id: <1616785332-165261-15-git-send-email-kan.liang@linux.intel.com>
Date:   Fri, 26 Mar 2021 12:02:01 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     acme@...nel.org, tglx@...utronix.de, bp@...en8.de,
        namhyung@...nel.org, jolsa@...hat.com, ak@...ux.intel.com,
        yao.jin@...ux.intel.com, alexander.shishkin@...ux.intel.com,
        adrian.hunter@...el.com, Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH V3 14/25] perf/x86: Remove temporary pmu assignment in event_init

From: Kan Liang <kan.liang@...ux.intel.com>

The temporary pmu assignment in event_init is unnecessary.

The assignment was introduced by commit 8113070d6639 ("perf_events:
Add fast-path to the rescheduling code"). At that time, event->pmu is
not assigned yet when initializing an event. The assignment is required.
However, from commit 7e5b2a01d2ca ("perf: provide PMU when initing
events"), the event->pmu is provided before event_init is invoked.
The temporary pmu assignment in event_init should be removed.

Reviewed-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/core.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index b79a506..9c931ec 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2299,7 +2299,6 @@ static int validate_group(struct perf_event *event)
 
 static int x86_pmu_event_init(struct perf_event *event)
 {
-	struct pmu *tmp;
 	int err;
 
 	switch (event->attr.type) {
@@ -2314,20 +2313,10 @@ static int x86_pmu_event_init(struct perf_event *event)
 
 	err = __x86_pmu_event_init(event);
 	if (!err) {
-		/*
-		 * we temporarily connect event to its pmu
-		 * such that validate_group() can classify
-		 * it as an x86 event using is_x86_event()
-		 */
-		tmp = event->pmu;
-		event->pmu = &pmu;
-
 		if (event->group_leader != event)
 			err = validate_group(event);
 		else
 			err = validate_event(event);
-
-		event->pmu = tmp;
 	}
 	if (err) {
 		if (event->destroy)
-- 
2.7.4