dca: check against empty dca_domains list before unregister provider

commit c419fcfd071cf34ba00f9f65282583772d2655e7 upstream.

When providers get blocked unregister_dca_providers() is called ending up
with dca_providers and dca_domain lists emptied. Dca should be prevented from
trying to unregister any provider if dca_domain list is found empty.

Reported-by: Jiang Liu <jiang.liu@huawei.com>
Tested-by: Gaohuai Han <hangaohuai@huawei.com>
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <djbw@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/dca/dca-core.c b/drivers/dca/dca-core.c
index 4abd089a094..7065851d0b7 100644
--- a/drivers/dca/dca-core.c
+++ b/drivers/dca/dca-core.c
@@ -409,6 +409,11 @@ void unregister_dca_provider(struct dca_provider *dca, struct device *dev)
 
         spin_lock_irqsave(&dca_lock, flags);
 
+        if (list_empty(&dca_domains)) {
+                raw_spin_unlock_irqrestore(&dca_lock, flags);
+                return;
+        }
+
         list_del(&dca->node);
 
         pci_rc = dca_pci_rc_from_dev(dev);