use guard(mutex) for scope based resource management of mutex.
This would make the code simpler and easier to maintain.

More details on lock guards can be found at
https://lore.kernel.org/all/20230612093537.614161713@infradead.org/T/#u (local)

There is also an example of using scoped_guard. 

Signed-off-by: Shrikanth Hegde <redacted>
---
 arch/powerpc/platforms/book3s/vas-api.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index 0b6365d85d11..eb1a97271afb 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c

@@ -425,7 +425,7 @@ static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
 		return VM_FAULT_SIGBUS;
 	}
 
-	mutex_lock(&txwin->task_ref.mmap_mutex);
+	guard(mutex)(&txwin->task_ref.mmap_mutex);
 	/*
 	 * The window may be inactive due to lost credit (Ex: core
 	 * removal with DLPAR). If the window is active again when

@@ -437,11 +437,9 @@ static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
 		if (paste_addr) {
 			fault = vmf_insert_pfn(vma, vma->vm_start,
 					(paste_addr >> PAGE_SHIFT));
-			mutex_unlock(&txwin->task_ref.mmap_mutex);
 			return fault;
 		}
 	}
-	mutex_unlock(&txwin->task_ref.mmap_mutex);