From: Chuck Ebbert <cebbert@redhat.com>
Date: Wed, 16 Apr 2008 02:45:05 +0000 (+0000)
Subject: acpi: bus: check once more for an empty list after locking it
X-Git-Tag: v2.6.24.5~5
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bcf7b3914e9cd04e09685a1460da8b90e46a8001;p=thirdparty%2Fkernel%2Fstable.git

acpi: bus: check once more for an empty list after locking it

upstream commit: f0a37e008750ead1751b7d5e89d220a260a46147

List could have become empty after the unlocked check that was made earlier,
so check again inside the lock.

Should fix https://bugzilla.redhat.com/show_bug.cgi?id=427765

Signed-off-by: Chuck Ebbert <cebbert@redhat.com>
Cc: <stable@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---

diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index f4487c38d9f29..3401e2cfd3ab0 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -350,10 +350,11 @@ int acpi_bus_receive_event(struct acpi_bus_event *event)
 	}
 
 	spin_lock_irqsave(&acpi_bus_event_lock, flags);
-	entry =
-	    list_entry(acpi_bus_event_list.next, struct acpi_bus_event, node);
-	if (entry)
+	if (!list_empty(&acpi_bus_event_list)) {
+		entry = list_entry(acpi_bus_event_list.next,
+				   struct acpi_bus_event, node);
 		list_del(&entry->node);
+	}
 	spin_unlock_irqrestore(&acpi_bus_event_lock, flags);
 
 	if (!entry)