linux-kernel - [PATCH] driver core: Fix device link deferred probe

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Date:   Thu,  2 Nov 2017 11:22:53 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>
Subject: [PATCH] driver core: Fix device link deferred probe

A device probe deferred because of a device link is never probed again
because it is not added to the deferred_probe_pending_list. Add it, taking
care of the race with driver_deferred_probe_trigger().

Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
---
 drivers/base/dd.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index ad44b40fe284..e4a5bef93344 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -350,6 +350,15 @@ int device_bind_driver(struct device *dev)
 static atomic_t probe_count = ATOMIC_INIT(0);
 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
 
+static void driver_deferred_probe_add_trigger(struct device *dev,
+					      int local_trigger_count)
+{
+	driver_deferred_probe_add(dev);
+	/* Did a trigger occur while probing? Need to re-trigger if yes */
+	if (local_trigger_count != atomic_read(&deferred_trigger_count))
+		driver_deferred_probe_trigger();
+}
+
 static int really_probe(struct device *dev, struct device_driver *drv)
 {
 	int ret = -EPROBE_DEFER;
@@ -369,6 +378,8 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 	}
 
 	ret = device_links_check_suppliers(dev);
+	if (ret == -EPROBE_DEFER)
+		driver_deferred_probe_add_trigger(dev, local_trigger_count);
 	if (ret)
 		return ret;
 
@@ -469,10 +480,7 @@ static int really_probe(struct device *dev, struct device_driver *drv)
 	case -EPROBE_DEFER:
 		/* Driver requested deferred probing */
 		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
-		driver_deferred_probe_add(dev);
-		/* Did a trigger occur while probing? Need to re-trigger if yes */
-		if (local_trigger_count != atomic_read(&deferred_trigger_count))
-			driver_deferred_probe_trigger();
+		driver_deferred_probe_add_trigger(dev, local_trigger_count);
 		break;
 	case -ENODEV:
 	case -ENXIO:
-- 
1.9.1