ubifs: work around high stack usage with clang (f4844b35) · Commits · 戴 / test

Building this file with clang can result in large stack usage as seen from this warning: fs/ubifs/auth.c:78:5: error: stack frame size of 1152 bytes in function 'ubifs_prepare_auth_node' The problem is that inlining ubifs_hash_calc_hmac() leads to two SHASH_DESC_ON_STACK() blocks in the same function, and clang for some reason does not reuse the stack space as it should. Putting the first declaration into a separate basic block avoids this problem and reduces the stack allocation to 640 bytes. Signed-off-by:

Arnd Bergmann <arnd@arndb.de> Reviewed-by:

Nick Desaulniers <ndesaulniers@google.com> Signed-off-by:

Richard Weinberger <richard@nod.at>

fs/ubifs/auth.c

+10 −7

Original line number	Diff line number	Diff line
		@@ -78,7 +78,6 @@ static int ubifs_hash_calc_hmac(const struct ubifs_info c, const u8 hash,
		int ubifs_prepare_auth_node(struct ubifs_info c, void node,
		struct shash_desc *inhash)
		{
		SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);
		struct ubifs_auth_node *auth = node;
		u8 *hash;
		int err;
		@@ -87,6 +86,9 @@ int ubifs_prepare_auth_node(struct ubifs_info c, void node,
		if (!hash)
		return -ENOMEM;

		{
		SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);

		hash_desc->tfm = c->hash_tfm;
		hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
		ubifs_shash_copy_state(c, inhash, hash_desc);
		@@ -94,6 +96,7 @@ int ubifs_prepare_auth_node(struct ubifs_info c, void node,
		err = crypto_shash_final(hash_desc, hash);
		if (err)
		goto out;
		}

		err = ubifs_hash_calc_hmac(c, hash, auth->hmac);
		if (err)

Admin message