Messages in this thread | | | Date | Thu, 30 Mar 2023 13:42:46 +0100 | Subject | Re: [PATCH v3 06/13] coresight: Fix loss of connection info when a module is unloaded | From | Suzuki K Poulose <> |
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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
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