From: Peter Hilber <peter.hilber@opensynergy.com>
To: Cristian Marussi <cristian.marussi@arm.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
virtualization@lists.linux-foundation.org,
virtio-dev@lists.oasis-open.org, sudeep.holla@arm.com,
james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com,
f.fainelli@gmail.com, etienne.carriere@linaro.org,
vincent.guittot@linaro.org, souvik.chakravarty@arm.com,
igor.skalkin@opensynergy.com, alex.bennee@linaro.org,
jean-philippe@linaro.org, mikhail.golubev@opensynergy.com,
anton.yakovlev@opensynergy.com, Vasyl.Vavrychuk@opensynergy.com,
Andriy.Tryshnivskyy@opensynergy.com
Subject: Re: [PATCH v6 07/17] firmware: arm_scmi: Handle concurrent and out-of-order messages
Date: Thu, 22 Jul 2021 10:32:58 +0200 [thread overview]
Message-ID: <85868de4-54bf-cca8-3786-61a404b80117@opensynergy.com> (raw)
In-Reply-To: <20210719091451.GF49078@e120937-lin>
On 19.07.21 11:14, Cristian Marussi wrote:
> On Thu, Jul 15, 2021 at 06:36:03PM +0200, Peter Hilber wrote:
>> On 12.07.21 16:18, Cristian Marussi wrote:
[snip]
>>> @@ -608,6 +755,7 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
>>> xfer->hdr.protocol_id, xfer->hdr.seq,
>>> xfer->hdr.poll_completion);
>>> + xfer->state = SCMI_XFER_SENT_OK;
>>
>> To be completely safe, this assignment could also be protected by the
>> xfer->lock.
>>
>
> In fact this would be true being xfer->lock meant to protect the state but it
> seemed to me unnecessary here given that this is a brand new xfer with a
> brand new (monotonic) seq number so that any possibly late-received msg will
> carry an old stale seq number certainly different from this such that cannot be
> possibly mapped to this same xfer. (but just discarded on xfer lookup in
> xfer_command_acquire)
>
> The issue indeed could still exist only for do_xfer loops (as you pointed out
> already early on) where the seq_num is used, but in that case on a timeout we
> would have already bailed out of the loop and reported an error so any timed-out
> late received response would have been anyway discarded; so at the end I thought
> I could avoid spinlocking here.
>
> Thanks,
> Cristian
>
I mostly meant to refer to the possibility of a very fast response not
seeing this assignment, since the next line is
> ret = info->desc->ops->send_message(cinfo, xfer);
and during that a regular scmi_rx_callback(), reading xfer->state, can
already arrive. But maybe this is too theoretical.
Best regards,
Peter
WARNING: multiple messages have this Message-ID (diff)
From: Peter Hilber <peter.hilber@opensynergy.com>
To: Cristian Marussi <cristian.marussi@arm.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
virtualization@lists.linux-foundation.org,
virtio-dev@lists.oasis-open.org, sudeep.holla@arm.com,
james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com,
f.fainelli@gmail.com, etienne.carriere@linaro.org,
vincent.guittot@linaro.org, souvik.chakravarty@arm.com,
igor.skalkin@opensynergy.com, alex.bennee@linaro.org,
jean-philippe@linaro.org, mikhail.golubev@opensynergy.com,
anton.yakovlev@opensynergy.com, Vasyl.Vavrychuk@opensynergy.com,
Andriy.Tryshnivskyy@opensynergy.com
Subject: Re: [PATCH v6 07/17] firmware: arm_scmi: Handle concurrent and out-of-order messages
Date: Thu, 22 Jul 2021 10:32:58 +0200 [thread overview]
Message-ID: <85868de4-54bf-cca8-3786-61a404b80117@opensynergy.com> (raw)
In-Reply-To: <20210719091451.GF49078@e120937-lin>
On 19.07.21 11:14, Cristian Marussi wrote:
> On Thu, Jul 15, 2021 at 06:36:03PM +0200, Peter Hilber wrote:
>> On 12.07.21 16:18, Cristian Marussi wrote:
[snip]
>>> @@ -608,6 +755,7 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
>>> xfer->hdr.protocol_id, xfer->hdr.seq,
>>> xfer->hdr.poll_completion);
>>> + xfer->state = SCMI_XFER_SENT_OK;
>>
>> To be completely safe, this assignment could also be protected by the
>> xfer->lock.
>>
>
> In fact this would be true being xfer->lock meant to protect the state but it
> seemed to me unnecessary here given that this is a brand new xfer with a
> brand new (monotonic) seq number so that any possibly late-received msg will
> carry an old stale seq number certainly different from this such that cannot be
> possibly mapped to this same xfer. (but just discarded on xfer lookup in
> xfer_command_acquire)
>
> The issue indeed could still exist only for do_xfer loops (as you pointed out
> already early on) where the seq_num is used, but in that case on a timeout we
> would have already bailed out of the loop and reported an error so any timed-out
> late received response would have been anyway discarded; so at the end I thought
> I could avoid spinlocking here.
>
> Thanks,
> Cristian
>
I mostly meant to refer to the possibility of a very fast response not
seeing this assignment, since the next line is
> ret = info->desc->ops->send_message(cinfo, xfer);
and during that a regular scmi_rx_callback(), reading xfer->state, can
already arrive. But maybe this is too theoretical.
Best regards,
Peter
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Peter Hilber <peter.hilber@opensynergy.com>
To: Cristian Marussi <cristian.marussi@arm.com>
Cc: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
virtualization@lists.linux-foundation.org,
virtio-dev@lists.oasis-open.org, sudeep.holla@arm.com,
james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com,
f.fainelli@gmail.com, etienne.carriere@linaro.org,
vincent.guittot@linaro.org, souvik.chakravarty@arm.com,
igor.skalkin@opensynergy.com, alex.bennee@linaro.org,
jean-philippe@linaro.org, mikhail.golubev@opensynergy.com,
anton.yakovlev@opensynergy.com, Vasyl.Vavrychuk@opensynergy.com,
Andriy.Tryshnivskyy@opensynergy.com
Subject: [virtio-dev] Re: [PATCH v6 07/17] firmware: arm_scmi: Handle concurrent and out-of-order messages
Date: Thu, 22 Jul 2021 10:32:58 +0200 [thread overview]
Message-ID: <85868de4-54bf-cca8-3786-61a404b80117@opensynergy.com> (raw)
In-Reply-To: <20210719091451.GF49078@e120937-lin>
On 19.07.21 11:14, Cristian Marussi wrote:
> On Thu, Jul 15, 2021 at 06:36:03PM +0200, Peter Hilber wrote:
>> On 12.07.21 16:18, Cristian Marussi wrote:
[snip]
>>> @@ -608,6 +755,7 @@ static int do_xfer(const struct scmi_protocol_handle *ph,
>>> xfer->hdr.protocol_id, xfer->hdr.seq,
>>> xfer->hdr.poll_completion);
>>> + xfer->state = SCMI_XFER_SENT_OK;
>>
>> To be completely safe, this assignment could also be protected by the
>> xfer->lock.
>>
>
> In fact this would be true being xfer->lock meant to protect the state but it
> seemed to me unnecessary here given that this is a brand new xfer with a
> brand new (monotonic) seq number so that any possibly late-received msg will
> carry an old stale seq number certainly different from this such that cannot be
> possibly mapped to this same xfer. (but just discarded on xfer lookup in
> xfer_command_acquire)
>
> The issue indeed could still exist only for do_xfer loops (as you pointed out
> already early on) where the seq_num is used, but in that case on a timeout we
> would have already bailed out of the loop and reported an error so any timed-out
> late received response would have been anyway discarded; so at the end I thought
> I could avoid spinlocking here.
>
> Thanks,
> Cristian
>
I mostly meant to refer to the possibility of a very fast response not
seeing this assignment, since the next line is
> ret = info->desc->ops->send_message(cinfo, xfer);
and during that a regular scmi_rx_callback(), reading xfer->state, can
already arrive. But maybe this is too theoretical.
Best regards,
Peter
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next prev parent reply other threads:[~2021-07-22 8:33 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-12 14:18 [PATCH v6 00/17] Introduce SCMI transport based on VirtIO Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 01/17] firmware: arm_scmi: Avoid padding in sensor message structure Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 02/17] firmware: arm_scmi: Fix max pending messages boundary check Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-14 16:46 ` Sudeep Holla
2021-07-14 16:46 ` Sudeep Holla
2021-07-12 14:18 ` [PATCH v6 03/17] firmware: arm_scmi: Add support for type handling in common functions Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 04/17] firmware: arm_scmi: Remove scmi_dump_header_dbg() helper Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 05/17] firmware: arm_scmi: Add transport optional init/exit support Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-28 11:40 ` Sudeep Holla
2021-07-28 11:40 ` Sudeep Holla
2021-07-28 12:28 ` Cristian Marussi
2021-07-28 12:28 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 06/17] firmware: arm_scmi: Introduce monotonically increasing tokens Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-28 14:17 ` Sudeep Holla
2021-07-28 14:17 ` Sudeep Holla
2021-07-28 16:54 ` Cristian Marussi
2021-07-28 16:54 ` [virtio-dev] " Cristian Marussi
2021-07-28 16:54 ` Cristian Marussi
2021-08-02 10:24 ` Sudeep Holla
2021-08-02 10:24 ` Sudeep Holla
2021-08-03 12:52 ` Cristian Marussi
2021-08-03 12:52 ` [virtio-dev] " Cristian Marussi
2021-08-03 12:52 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 07/17] firmware: arm_scmi: Handle concurrent and out-of-order messages Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-15 16:36 ` Peter Hilber
2021-07-15 16:36 ` [virtio-dev] " Peter Hilber
2021-07-15 16:36 ` Peter Hilber
2021-07-19 9:14 ` Cristian Marussi
2021-07-19 9:14 ` Cristian Marussi
2021-07-22 8:32 ` Peter Hilber [this message]
2021-07-22 8:32 ` [virtio-dev] " Peter Hilber
2021-07-22 8:32 ` Peter Hilber
2021-07-28 8:31 ` Cristian Marussi
2021-07-28 8:31 ` Cristian Marussi
2021-08-02 10:10 ` Sudeep Holla
2021-08-02 10:10 ` Sudeep Holla
2021-08-02 10:27 ` Cristian Marussi
2021-08-02 10:27 ` [virtio-dev] " Cristian Marussi
2021-08-02 10:27 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 08/17] firmware: arm_scmi: Add priv parameter to scmi_rx_callback Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-28 14:26 ` Sudeep Holla
2021-07-28 14:26 ` Sudeep Holla
2021-07-28 17:25 ` Cristian Marussi
2021-07-28 17:25 ` [virtio-dev] " Cristian Marussi
2021-07-28 17:25 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 09/17] firmware: arm_scmi: Make .clear_channel optional Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 10/17] firmware: arm_scmi: Make polling mode optional Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-15 16:36 ` Peter Hilber
2021-07-15 16:36 ` [virtio-dev] " Peter Hilber
2021-07-15 16:36 ` Peter Hilber
2021-07-19 9:15 ` Cristian Marussi
2021-07-19 9:15 ` Cristian Marussi
2021-07-28 14:34 ` Sudeep Holla
2021-07-28 14:34 ` Sudeep Holla
2021-07-28 17:41 ` Cristian Marussi
2021-07-28 17:41 ` [virtio-dev] " Cristian Marussi
2021-07-28 17:41 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 11/17] firmware: arm_scmi: Make SCMI transports configurable Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-28 14:50 ` Sudeep Holla
2021-07-28 14:50 ` Sudeep Holla
2021-07-29 16:18 ` Cristian Marussi
2021-07-29 16:18 ` [virtio-dev] " Cristian Marussi
2021-07-29 16:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 12/17] firmware: arm_scmi: Make shmem support optional for transports Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 13/17] firmware: arm_scmi: Add method to override max message number Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 14/17] firmware: arm_scmi: Add message passing abstractions for transports Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-15 16:36 ` Peter Hilber
2021-07-15 16:36 ` [virtio-dev] " Peter Hilber
2021-07-15 16:36 ` Peter Hilber
2021-07-19 9:16 ` Cristian Marussi
2021-07-19 9:16 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 15/17] firmware: arm_scmi: Add optional link_supplier() transport op Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-28 15:36 ` Sudeep Holla
2021-07-28 15:36 ` Sudeep Holla
2021-07-29 16:19 ` Cristian Marussi
2021-07-29 16:19 ` [virtio-dev] " Cristian Marussi
2021-07-29 16:19 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 16/17] dt-bindings: arm: Add virtio transport for SCMI Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-12 14:18 ` [PATCH v6 17/17] firmware: arm_scmi: Add virtio transport Cristian Marussi
2021-07-12 14:18 ` Cristian Marussi
2021-07-15 16:35 ` [PATCH v6 00/17] Introduce SCMI transport based on VirtIO Peter Hilber
2021-07-15 16:35 ` [virtio-dev] " Peter Hilber
2021-07-15 16:35 ` Peter Hilber
2021-07-19 11:36 ` Cristian Marussi
2021-07-19 11:36 ` Cristian Marussi
2021-07-22 8:30 ` Peter Hilber
2021-07-22 8:30 ` [virtio-dev] " Peter Hilber
2021-07-22 8:30 ` Peter Hilber
2021-08-11 9:31 ` Floris Westermann
2021-08-11 9:31 ` Floris Westermann
2021-08-11 15:26 ` Cristian Marussi
2021-08-11 15:26 ` [virtio-dev] " Cristian Marussi
2021-08-11 15:26 ` Cristian Marussi
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