gcc-10: avoid shadowing standard library 'free()' in crypto

gcc-10 has started warning about conflicting types for a few new
built-in functions, particularly 'free()'.

This results in warnings like:

   crypto/xts.c:325:13: warning: conflicting types for built-in function ‘free’; expected ‘void(void *)’ [-Wbuiltin-declaration-mismatch]

because the crypto layer had its local freeing functions called
'free()'.

Gcc-10 is in the wrong here, since that function is marked 'static', and
thus there is no chance of confusion with any standard library function
namespace.

But the simplest thing to do is to just use a different name here, and
avoid this gcc mis-feature.

[ Side note: gcc knowing about 'free()' is in itself not the
  mis-feature: the semantics of 'free()' are special enough that a
  compiler can validly do special things when seeing it.

  So the mis-feature here is that gcc thinks that 'free()' is some
  restricted name, and you can't shadow it as a local static function.

  Making the special 'free()' semantics be a function attribute rather
  than tied to the name would be the much better model ]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 6 insertions, 6 deletions

diff --git a/crypto/lrw.c b/crypto/lrw.c
index 376d7ed3f1f8..3c734b81b3a2 100644
--- a/crypto/lrw.c
+++ b/crypto/lrw.c
@@ -287,7 +287,7 @@ static void exit_tfm(struct crypto_skcipher *tfm)
 	crypto_free_skcipher(ctx->child);
 }
 
-static void free(struct skcipher_instance *inst)
+static void free_inst(struct skcipher_instance *inst)
 {
 	crypto_drop_skcipher(skcipher_instance_ctx(inst));
 	kfree(inst);
@@ -400,12 +400,12 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->alg.encrypt = encrypt;
 	inst->alg.decrypt = decrypt;
 
-	inst->free = free;
+	inst->free = free_inst;
 
 	err = skcipher_register_instance(tmpl, inst);
 	if (err) {
 err_free_inst:
-		free(inst);
+		free_inst(inst);
 	}
 	return err;
 }
diff --git a/crypto/xts.c b/crypto/xts.c
index dbdd8af629e6..6d8cea94b3cf 100644
--- a/crypto/xts.c
+++ b/crypto/xts.c
@@ -322,7 +322,7 @@ static void exit_tfm(struct crypto_skcipher *tfm)
 	crypto_free_cipher(ctx->tweak);
 }
 
-static void free(struct skcipher_instance *inst)
+static void free_inst(struct skcipher_instance *inst)
 {
 	crypto_drop_skcipher(skcipher_instance_ctx(inst));
 	kfree(inst);
@@ -434,12 +434,12 @@ static int create(struct crypto_template *tmpl, struct rtattr **tb)
 	inst->alg.encrypt = encrypt;
 	inst->alg.decrypt = decrypt;
 
-	inst->free = free;
+	inst->free = free_inst;
 
 	err = skcipher_register_instance(tmpl, inst);
 	if (err) {
 err_free_inst:
-		free(inst);
+		free_inst(inst);
 	}
 	return err;
 }