drivers: base: devres: Allow to release group on device release

When releasing a device, if the release action causes a group to be
released, a warning is emitted because it can't find the group. This
happens because devres_release_all() moves the entire list to a todo
list and also move the group markers. Considering r* normal resource
nodes and g1 a group resource node:

		    g1 -----------.
		    v		  v
	r1 -> r2 -> g1[0] -> r3-> g[1] -> r4

After devres_release_all(), dev->devres_head becomes empty and the todo
list it iterates on becomes:

			       g1
			       v
	r1 -> r2 -> r3-> r4 -> g1[0]

When a call to component_del() is made and takes down the aggregate
device, a warning like this happen:

	RIP: 0010:devres_release_group+0x362/0x530
	...
	Call Trace:
	 <TASK>
	 component_unbind+0x156/0x380
	 component_unbind_all+0x1d0/0x270
	 mei_component_master_unbind+0x28/0x80 [mei_hdcp]
	 take_down_aggregate_device+0xc1/0x160
	 component_del+0x1c6/0x3e0
	 intel_hdcp_component_fini+0xf1/0x170 [xe]
	 xe_display_fini+0x1e/0x40 [xe]

Because the devres group corresponding to the hdcp component cannot be
found. Just ignore this corner case: if the dev->devres_head is empty
and the caller is trying to remove a group, it's likely in the process
of device cleanup so just ignore it instead of warning.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250222001051.3012936-2-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 2152eec0c1352cc46bdef703123e9f2d718bf111..68224f2f83fff2653732070da146eecf3e48f8fe 100644 (file)
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -687,6 +687,13 @@ int devres_release_group(struct device *dev, void *id)
                spin_unlock_irqrestore(&dev->devres_lock, flags);
 
                release_nodes(dev, &todo);
+       } else if (list_empty(&dev->devres_head)) {
+               /*
+                * dev is probably dying via devres_release_all(): groups
+                * have already been removed and are on the process of
+                * being released - don't touch and don't warn.
+                */
+               spin_unlock_irqrestore(&dev->devres_lock, flags);
        } else {
                WARN_ON(1);
                spin_unlock_irqrestore(&dev->devres_lock, flags);