linux-kernel - [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly

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Message-Id: <ed589c0d8e4130dc68b8ad1625226d28bdc185d4.1702322847.git.robin.murphy@arm.com>
Date:   Mon, 11 Dec 2023 19:27:28 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     will@...nel.org
Cc:     mark.rutland@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, jeremy.linton@....com,
        ilkka@...amperecomputing.com, renyu.zj@...ux.alibaba.com
Subject: [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly

Calling arm_cmn_event_clear() before all DTC indices are allocated is
wrong, and can lead to arm_cmn_event_add() erroneously clearing live
counters from full DTCs where allocation fails. Since the DTC counters
are only updated by arm_cmn_init_counter() after all DTC and DTM
allocations succeed, nothing actually needs cleaning up in this case
anyway, and it should just return directly as it did before.

Fixes: 7633ec2c262f ("perf/arm-cmn: Rework DTC counters (again)")
Signed-off-by: Robin Murphy <robin.murphy@....com>
---
 drivers/perf/arm-cmn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 86d970e74129..c584165b13ba 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -1816,7 +1816,7 @@ static int arm_cmn_event_add(struct perf_event *event, int flags)
 			idx = 0;
 			while (cmn->dtc[j].counters[idx])
 				if (++idx == CMN_DT_NUM_COUNTERS)
-					goto free_dtms;
+					return -ENOSPC;
 		}
 		hw->dtc_idx[j] = idx;
 	}
-- 
2.39.2.101.g768bb238c484.dirty