linux-kernel - [PATCH 1/1] driver core: Remove warning on driver unbinding

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Message-ID: <20231110080241.702999-1-herve.codina@bootlin.com>
Date:   Fri, 10 Nov 2023 09:02:40 +0100
From:   Herve Codina <herve.codina@...tlin.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Saravana Kannan <saravanak@...gle.com>
Cc:     linux-kernel@...r.kernel.org,
        Allan Nielsen <allan.nielsen@...rochip.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Steen Hegelund <steen.hegelund@...rochip.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Herve Codina <herve.codina@...tlin.com>, stable@...r.kernel.org
Subject: [PATCH 1/1] driver core: Remove warning on driver unbinding

During driver unbinding, __device_links_no_driver() can raise the
following warning:
   --- 8< ---
   WARNING: CPU: 0 PID: 166 at drivers/base/core.c:1426 __device_links_no_driver+0xac/0xb4
   ...
   Call trace:
   __device_links_no_driver+0xac/0xb4
   device_links_driver_cleanup+0xa8/0xf0
   device_release_driver_internal+0x204/0x240
   device_release_driver+0x18/0x24
   bus_remove_device+0xcc/0x10c
   device_del+0x158/0x414
   platform_device_del.part.0+0x1c/0x88
   platform_device_unregister+0x24/0x40
   of_platform_device_destroy+0xfc/0x10c
   device_for_each_child_reverse+0x64/0xb4
   devm_of_platform_populate_release+0x4c/0x84
   release_nodes+0x5c/0x90
   devres_release_all+0x8c/0xdc
   device_unbind_cleanup+0x18/0x68
   device_release_driver_internal+0x20c/0x240
   device_links_unbind_consumers+0xe0/0x108
   device_release_driver_internal+0xf0/0x240
   driver_detach+0x50/0x9c
   bus_remove_driver+0x6c/0xbc
   driver_unregister+0x30/0x60
   ...
   --- 8< ---

This warning is raised because, during device removal, we unlink a
consumer while its supplier links.status is DL_DEV_UNBINDING.
Even if the link is not a SYNC_STATE_ONLY, the warning should not
appear in that case.

Filter out this warning in case of the supplier driver is unbinding.

Fixes: 8c3e315d4296 ("driver core: Update device link status correctly for SYNC_STATE_ONLY links")
Cc: stable@...r.kernel.org
Signed-off-by: Herve Codina <herve.codina@...tlin.com>
---
 drivers/base/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 17f2568e0a79..f4b09691998e 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1423,7 +1423,8 @@ static void __device_links_no_driver(struct device *dev)
 		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
 		} else {
-			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY) &&
+				link->supplier->links.status != DL_DEV_UNBINDING);
 			WRITE_ONCE(link->status, DL_STATE_DORMANT);
 		}
 	}
-- 
2.41.0