From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: James Clark <james.clark@arm.com>,
coresight@lists.linaro.org, quic_jinlmao@quicinc.com,
mike.leach@linaro.org
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
Leo Yan <leo.yan@linaro.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Maxime Coquelin <mcoquelin.stm32@gmail.com>,
Alexandre Torgue <alexandre.torgue@foss.st.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com
Subject: Re: [PATCH v3 06/13] coresight: Fix loss of connection info when a module is unloaded
Date: Thu, 30 Mar 2023 13:42:46 +0100 [thread overview]
Message-ID: <d398a5c4-90f1-e717-fb73-d621f5ea845b@arm.com> (raw)
In-Reply-To: <20230329115329.2747724-7-james.clark@arm.com>
Hi James
On 29/03/2023 12:53, James Clark wrote:
> child_fwnode should be a read only property based on the DT. If it's
> cleared on the parent device when a child is unloaded, then when the
> child is loaded again the connection won't be remade.
>
> child_dev should be cleared instead which signifies that the connection
> should be remade when the child_fwnode registers a new coresight_device.
>
> Similarly the reference count shouldn't be decremented as long as the
> parent device exists. The correct place to drop the reference is in
> coresight_release_platform_data() which is already done.
>
> Signed-off-by: James Clark <james.clark@arm.com>
This looks like a bug in the existing driver. Please could you keep this
at the beginning of the series, so that it is easier to backport for
stable ?
Also, please add :
Fixes: 37ea1ffddffa ("coresight: Use fwnode handle instead of device names")
Fixes: 2af89ebacf29 ("coresight: Clear the connection field properly")
> ---
> drivers/hwtracing/coresight/coresight-core.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index bfe1b93aca4e..12cbb68e8e1c 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -1414,13 +1414,8 @@ static int coresight_remove_match(struct device *dev, void *data)
> if (csdev->dev.fwnode == conn->dest_fwnode) {
> iterator->orphan = true;
> coresight_remove_links(iterator, conn);
> - /*
> - * Drop the reference to the handle for the remote
> - * device acquired in parsing the connections from
> - * platform data.
> - */
> - fwnode_handle_put(conn->dest_fwnode);
> - conn->dest_fwnode = NULL;
> +
> + conn->dest_dev = NULL;
> /* No need to continue */
> break;
> }
> @@ -1553,7 +1548,6 @@ void coresight_release_platform_data(struct coresight_device *csdev,
> * is going away
> */
> fwnode_handle_put(conns[i].dest_fwnode);
> - pdata->out_conns[i].dest_fwnode = NULL;
This change is not required, as we are freeing the pdata anyway.
Keeping this might be beneficial if someone else comes looking
for references while we are going out. I don't see how we could
hit that, but just to be safe.
Suzuki
next prev parent reply other threads:[~2023-03-30 12:42 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-29 11:53 [PATCH v3 00/13] coresight: Fix CTI module refcount leak by making it a helper device James Clark
2023-03-29 11:53 ` [PATCH v3 01/13] coresight: Use enum type for cs_mode wherever possible James Clark
2023-03-29 11:53 ` [PATCH v3 02/13] coresight: Change name of pdata->conns James Clark
2023-03-29 11:53 ` [PATCH v3 03/13] coresight: Rename nr_outports to nr_outconns James Clark
2023-03-29 11:53 ` [PATCH v3 04/13] coresight: Rename connection members to make the direction explicit James Clark
2023-03-29 11:53 ` [PATCH v3 05/13] coresight: Dynamically add connections James Clark
2023-03-29 11:53 ` [PATCH v3 06/13] coresight: Fix loss of connection info when a module is unloaded James Clark
2023-03-30 12:42 ` Suzuki K Poulose [this message]
2023-03-30 14:01 ` Suzuki K Poulose
2023-03-29 11:53 ` [PATCH v3 07/13] coresight: Store pointers to connections rather than an array of them James Clark
2023-04-03 8:46 ` Suzuki K Poulose
2023-04-03 10:16 ` James Clark
2023-04-03 11:11 ` Suzuki K Poulose
2023-03-29 11:53 ` [PATCH v3 08/13] coresight: Simplify connection fixup mechanism James Clark
2023-04-03 9:18 ` Suzuki K Poulose
2023-03-29 11:53 ` [PATCH v3 09/13] coresight: Store in-connections as well as out-connections James Clark
2023-04-03 10:17 ` Suzuki K Poulose
2023-03-29 11:53 ` [PATCH v3 10/13] coresight: Make refcount a property of the connection James Clark
2023-04-03 11:47 ` Suzuki K Poulose
2023-04-03 14:13 ` James Clark
2023-03-29 11:53 ` [PATCH v3 11/13] coresight: Refactor out buffer allocation function for ETR James Clark
2023-03-29 11:53 ` [PATCH v3 12/13] coresight: Enable and disable helper devices adjacent to the path James Clark
2023-04-03 17:54 ` Suzuki K Poulose
2023-03-29 11:53 ` [PATCH v3 13/13] coresight: Fix CTI module refcount leak by making it a helper device James Clark
2023-04-04 9:21 ` Suzuki K Poulose
2023-04-04 12:55 ` James Clark
2023-04-04 13:04 ` James Clark
2023-04-04 13:59 ` Suzuki K Poulose
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