From: Ilkka Koskinen <ilkka@os.amperecomputing.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: will@kernel.org, mark.rutland@arm.com,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, jeremy.linton@arm.com,
ilkka@os.amperecomputing.com, renyu.zj@linux.alibaba.com
Subject: Re: [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly
Date: Mon, 11 Dec 2023 18:21:34 -0800 (PST) [thread overview]
Message-ID: <bf20c32f-6426-f4ba-3bcc-41aadd89968@os.amperecomputing.com> (raw)
In-Reply-To: <ed589c0d8e4130dc68b8ad1625226d28bdc185d4.1702322847.git.robin.murphy@arm.com>
On Mon, 11 Dec 2023, Robin Murphy wrote:
> 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@arm.com>
That's a good catch.
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Cheers, Ilkka
> ---
> 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
>
>
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next prev parent reply other threads:[~2023-12-12 2:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-11 19:27 [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly Robin Murphy
2023-12-12 2:21 ` Ilkka Koskinen [this message]
2023-12-12 9:16 ` Will Deacon
2023-12-12 17:22 ` Catalin Marinas
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