* [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly
@ 2023-12-11 19:27 Robin Murphy
2023-12-12 2:21 ` Ilkka Koskinen
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Robin Murphy @ 2023-12-11 19:27 UTC (permalink / raw)
To: will
Cc: mark.rutland, linux-arm-kernel, linux-kernel, jeremy.linton,
ilkka, renyu.zj
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>
---
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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^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly
2023-12-11 19:27 [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly Robin Murphy
@ 2023-12-12 2:21 ` Ilkka Koskinen
2023-12-12 9:16 ` Will Deacon
2023-12-12 17:22 ` Catalin Marinas
2 siblings, 0 replies; 4+ messages in thread
From: Ilkka Koskinen @ 2023-12-12 2:21 UTC (permalink / raw)
To: Robin Murphy
Cc: will, mark.rutland, linux-arm-kernel, linux-kernel, jeremy.linton,
ilkka, renyu.zj
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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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly
2023-12-11 19:27 [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly Robin Murphy
2023-12-12 2:21 ` Ilkka Koskinen
@ 2023-12-12 9:16 ` Will Deacon
2023-12-12 17:22 ` Catalin Marinas
2 siblings, 0 replies; 4+ messages in thread
From: Will Deacon @ 2023-12-12 9:16 UTC (permalink / raw)
To: Robin Murphy, catalin.marinas
Cc: mark.rutland, linux-arm-kernel, linux-kernel, jeremy.linton,
ilkka, renyu.zj
On Mon, Dec 11, 2023 at 07:27:28PM +0000, 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>
> ---
> 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
Acked-by: Will Deacon <will@kernel.org>
Catalin -- please can you take this one as a fix?
Cheers,
Will
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^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly
2023-12-11 19:27 [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly Robin Murphy
2023-12-12 2:21 ` Ilkka Koskinen
2023-12-12 9:16 ` Will Deacon
@ 2023-12-12 17:22 ` Catalin Marinas
2 siblings, 0 replies; 4+ messages in thread
From: Catalin Marinas @ 2023-12-12 17:22 UTC (permalink / raw)
To: will, Robin Murphy
Cc: mark.rutland, linux-arm-kernel, linux-kernel, jeremy.linton,
ilkka, renyu.zj
On Mon, 11 Dec 2023 19:27:28 +0000, 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.
>
> [...]
Applied to arm64 (for-next/fixes), thanks!
[1/1] perf/arm-cmn: Fail DTC counter allocation correctly
https://git.kernel.org/arm64/c/1892fe103c3a
--
Catalin
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2023-12-11 19:27 [PATCH] perf/arm-cmn: Fail DTC counter allocation correctly Robin Murphy
2023-12-12 2:21 ` Ilkka Koskinen
2023-12-12 9:16 ` Will Deacon
2023-12-12 17:22 ` Catalin Marinas
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