hw_random: cleanup in hwrng_register()

My static checker complains that:

drivers/char/hw_random/core.c:341 hwrng_register()
warn: we tested 'old_rng' before and it was 'false'

The problem is that sometimes we test "if (!old_rng)" and sometimes we test "if (must_register_misc)". The static checker knows they are equivalent but a human being reading the code could easily be confused.

I have simplified the code by removing the "must_register_misc" variable and I have removed the redundant check on "if (!old_rng)".

Signed-off-by Dan Carpenter <[email protected]>

drivers/char/hw_random/core.c +3 -7

index b9495a8c05c6..463382036a01 100644
@@ -301,7 +301,6 @@ err_misc_dereg:
 
 int hwrng_register(struct hwrng *rng)
 {
-	int must_register_misc;
 	int err = -EINVAL;
 	struct hwrng *old_rng, *tmp;
 

@@ -326,7 +325,6 @@ int hwrng_register(struct hwrng *rng)
 			goto out_unlock;
 	}
 
-	must_register_misc = (current_rng = NULL);
 	old_rng = current_rng;
 	if (!old_rng) {
 		err = hwrng_init(rng);

@@ -335,13 +333,11 @@ int hwrng_register(struct hwrng *rng)
 		current_rng = rng;
 	}
 	err = 0;
-	if (must_register_misc) {
+	if (!old_rng) {
 		err = register_miscdev();
 		if (err) {
-			if (!old_rng) {
-				hwrng_cleanup(rng);
-				current_rng = NULL;
-			}
+			hwrng_cleanup(rng);
+			current_rng = NULL;
 			goto out_unlock;
 		}
 	}

Quoted 9 lines · Dan Carpenter

My static checker complains that:

drivers/char/hw_random/core.c:341 hwrng_register()
warn: we tested 'old_rng' before and it was 'false'

The problem is that sometimes we test "if (!old_rng)" and sometimes we test "if (must_register_misc)". The static checker knows they are equivalent but a human being reading the code could easily be confused.

Quoted 4 lines

I have simplified the code by removing the "must_register_misc" variable and I have removed the redundant check on "if (!old_rng)".

Signed-off-by Dan Carpenter <[email protected]>

Yeah, clearer too.

Reviewed-by Rusty Russell <[email protected]>