linux-kernel - [PATCH V3 2/3] driver core: Add ability to delete device links of unregistered devices

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Date:   Sat, 10 Jul 2021 13:38:18 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Saravana Kannan <saravanak@...gle.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        linux-scsi@...r.kernel.org, Avri Altman <avri.altman@....com>,
        Bean Huo <huobean@...il.com>, Can Guo <cang@...eaurora.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        Bart Van Assche <bvanassche@....org>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH V3 2/3] driver core: Add ability to delete device links of unregistered devices

Managed device links are deleted by device_del(). However it is possible to
add a device link to a consumer before device_add(), and then discover an
error prevents the device from being used. In that case normally references
to the device would be dropped and the device would be deleted. However the
device link holds a reference to the device, so the device link and device
remain indefinitely (unless the supplier is deleted).

Amend device link removal to accept removal of a link with an
unregistered consumer device.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun")
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 drivers/base/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 2de8f7d8cf54..983e895d4ced 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -887,6 +887,8 @@ static void device_link_put_kref(struct device_link *link)
 {
 	if (link->flags & DL_FLAG_STATELESS)
 		kref_put(&link->kref, __device_link_del);
+	else if (!device_is_registered(link->consumer))
+		__device_link_del(&link->kref);
 	else
 		WARN(1, "Unable to drop a managed device link reference\n");
 }
-- 
2.17.1