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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>
This commit is contained in:
Davidlohr Bueso 2019-11-01 13:00:04 -07:00 committed by Sasha Levin
parent d7f0b2e450
commit 8aea7f8215
1 changed files with 5 additions and 5 deletions
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10
drivers/hv/vmbus_drv.c
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@ -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);