linux-kernel - [PATCH 4.19 33/56] PM: runtime: Fix ordering in pm_runtime_get

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Message-Id: <20210405085023.595776147@linuxfoundation.org>
Date:   Mon,  5 Apr 2021 10:54:04 +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, Adrian Hunter <adrian.hunter@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.19 33/56] PM: runtime: Fix ordering in pm_runtime_get_suppliers()

From: Adrian Hunter <adrian.hunter@...el.com>

commit c0c33442f7203704aef345647e14c2fb86071001 upstream.

rpm_active indicates how many times the supplier usage_count has been
incremented. Consequently it must be updated after pm_runtime_get_sync() of
the supplier, not before.

Fixes: 4c06c4e6cf63 ("driver core: Fix possible supplier PM-usage counter imbalance")
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Cc: 5.1+ <stable@...r.kernel.org> # 5.1+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/base/power/runtime.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1572,8 +1572,8 @@ void pm_runtime_get_suppliers(struct dev
 	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
 		if (link->flags & DL_FLAG_PM_RUNTIME) {
 			link->supplier_preactivated = true;
-			refcount_inc(&link->rpm_active);
 			pm_runtime_get_sync(link->supplier);
+			refcount_inc(&link->rpm_active);
 		}
 
 	device_links_read_unlock(idx);