linux-kernel - [PATCH 5.6 100/126] driver core: Fix handling of SYNC_STATE

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Date:   Tue, 26 May 2020 20:53:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Saravana Kannan <saravanak@...gle.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 5.6 100/126] driver core: Fix handling of SYNC_STATE_ONLY + STATELESS device links

From: Saravana Kannan <saravanak@...gle.com>

commit 44e960490ddf868fc9135151c4a658936e771dc2 upstream.

Commit 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link
implementation") didn't completely fix STATELESS + SYNC_STATE_ONLY
handling.

What looks like an optimization in that commit is actually a bug that
causes an if condition to always take the else path. This prevents
reordering of devices in the dpm_list when a DL_FLAG_STATELESS device
link is create on top of an existing DL_FLAG_SYNC_STATE_ONLY device
link.

Fixes: 21c27f06587d ("driver core: Fix SYNC_STATE_ONLY device link implementation")
Signed-off-by: Saravana Kannan <saravanak@...gle.com>
Cc: stable <stable@...r.kernel.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Link: https://lore.kernel.org/r/20200520043626.181820-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/base/core.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -360,12 +360,14 @@ struct device_link *device_link_add(stru

 		if (flags & DL_FLAG_STATELESS) {
 			kref_get(&link->kref);
-			link->flags |= DL_FLAG_STATELESS;
 			if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
-			    !(link->flags & DL_FLAG_STATELESS))
+			    !(link->flags & DL_FLAG_STATELESS)) {
+				link->flags |= DL_FLAG_STATELESS;
 				goto reorder;
-			else
+			} else {
+				link->flags |= DL_FLAG_STATELESS;
 				goto out;
+			}
 		}

 		/*