[PATCH 2/2] driver core: Guard deferred probe timeout extension with delayed_work_pending()

[Danilo Krummrich <dakr@kernel.org>]

mod_delayed_work() unconditionally queues the work even when it wasn't
previously pending, which can fire the timeout prematurely or restart it
after it already fired. Add a delayed_work_pending() guard to restore
the originally intended semantics.

Premature firing calls fw_devlink_drivers_done() before all built-in
drivers have registered, causing fw_devlink to prematurely relax device
links for suppliers whose drivers haven't loaded yet.

Fixes: 1137838865bf ("driver core: Use mod_delayed_work to prevent lost deferred probe work")
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
 drivers/base/dd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index bebb43acc132..905269ecef9b 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -323,7 +323,8 @@ void deferred_probe_extend_timeout(void)
 	 * If the work hasn't been queued yet or if the work expired, don't
 	 * start a new one.
 	 */
-	if (mod_delayed_work(system_wq, &deferred_probe_timeout_work,
+	if (delayed_work_pending(&deferred_probe_timeout_work) &&
+	    mod_delayed_work(system_wq, &deferred_probe_timeout_work,
 			     secs_to_jiffies(driver_deferred_probe_timeout)))
 		pr_debug("Extended deferred probe timeout by %d secs\n",
 					driver_deferred_probe_timeout);
-- 
2.54.0