driver core: clear deferred probe reason on probe retry

commit f0acf637d60ffcef3ccb6e279f743e587b3c7359 upstream.

When retrying a deferred probe, any old defer reason string should be
discarded. Otherwise, if the probe is deferred again at a different spot,
but without setting a message, the now incorrect probe reason will remain.

This was observed with the i.MX I2C driver, which ultimately failed
to probe due to lack of the GPIO driver. The probe defer for GPIO
doesn't record a message, but a previous probe defer to clock_get did.
This had the effect that /sys/kernel/debug/devices_deferred listed
a misleading probe deferral reason.

Cc: stable <stable@vger.kernel.org>
Fixes: d090b70ede02 ("driver core: add deferring probe reason to devices_deferred property")
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210319110459.19966-1-a.fatoum@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index 3c94ebc..43130d6 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -97,6 +97,9 @@ static void deferred_probe_work_func(struct work_struct *work)
 
                get_device(dev);
 
+               kfree(dev->p->deferred_probe_reason);
+               dev->p->deferred_probe_reason = NULL;
+
                /*
                 * Drop the mutex while probing each device; the probe path may
                 * manipulate the deferred list