drivers/hv: Replace binary semaphore with mutex

At a slight footprint cost (24 vs 32 bytes), mutexes are more optimal
than semaphores; it's also a nicer interface for mutual exclusion,
which is why they are encouraged over binary semaphores, when possible.

Replace the hyperv_mmio_lock, its semantics implies traditional lock
ownership; that is, the lock owner is the same for both lock/unlock
operations. Therefore it is safe to convert.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 5d2304b4b9c8018f11275c1f93b9061a892a2d44..845d2a9423ea9c9f1ef3ba5fee4af0f28b75b1eb 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -79,7 +79,7 @@ static struct notifier_block hyperv_panic_block = {
 static const char *fb_mmio_name = "fb_range";
 static struct resource *fb_mmio;
 static struct resource *hyperv_mmio;
-static DEFINE_SEMAPHORE(hyperv_mmio_lock);
+static DEFINE_MUTEX(hyperv_mmio_lock);
 
 static int vmbus_exists(void)
 {
@@ -2018,7 +2018,7 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
        int retval;
 
        retval = -ENXIO;
-       down(&hyperv_mmio_lock);
+       mutex_lock(&hyperv_mmio_lock);
 
        /*
         * If overlaps with frame buffers are allowed, then first attempt to
@@ -2065,7 +2065,7 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
        }
 
 exit:
-       up(&hyperv_mmio_lock);
+       mutex_unlock(&hyperv_mmio_lock);
        return retval;
 }
 EXPORT_SYMBOL_GPL(vmbus_allocate_mmio);
@@ -2082,7 +2082,7 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
 {
        struct resource *iter;
 
-       down(&hyperv_mmio_lock);
+       mutex_lock(&hyperv_mmio_lock);
        for (iter = hyperv_mmio; iter; iter = iter->sibling) {
                if ((iter->start >= start + size) || (iter->end <= start))
                        continue;
@@ -2090,7 +2090,7 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
                __release_region(iter, start, size);
        }
        release_mem_region(start, size);
-       up(&hyperv_mmio_lock);
+       mutex_unlock(&hyperv_mmio_lock);
 
 }
 EXPORT_SYMBOL_GPL(vmbus_free_mmio);