[hare-scsi-devel:tls-upcall.v4 118/156] crypto/hkdf.c:26:5: warning: no previous prototype for 'hkdf_extract'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git tls-upcall.v4
head:   d2416ecdb6b03fc2e4aa40b20cdf919322713224
commit: ea4c6fc32e5e02a1e4c841f462c3a931b8838f33 [118/156] crypto,fs: Separate out hkdf_extract() and hkdf_expand()
config: i386-randconfig-a003 (https://download.01.org/0day-ci/archive/20220313/202203132024.aYz79iM0-lkp@intel.com/config)
compiler: gcc-9 (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git/commit/?id=ea4c6fc32e5e02a1e4c841f462c3a931b8838f33
        git remote add hare-scsi-devel https://git.kernel.org/pub/scm/linux/kernel/git/hare/scsi-devel.git
        git fetch --no-tags hare-scsi-devel tls-upcall.v4
        git checkout ea4c6fc32e5e02a1e4c841f462c3a931b8838f33
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> crypto/hkdf.c:26:5: warning: no previous prototype for 'hkdf_extract' [-Wmissing-prototypes]
      26 | int hkdf_extract(struct crypto_shash *hmac_tfm, const u8 *ikm,
         |     ^~~~~~~~~~~~
>> crypto/hkdf.c:52:5: warning: no previous prototype for 'hkdf_expand' [-Wmissing-prototypes]
      52 | int hkdf_expand(struct crypto_shash *hmac_tfm,
         |     ^~~~~~~~~~~


vim +/hkdf_extract +26 crypto/hkdf.c

    14	
    15	/*
    16	 * HKDF consists of two steps:
    17	 *
    18	 * 1. HKDF-Extract: extract a pseudorandom key of length HKDF_HASHLEN bytes from
    19	 *    the input keying material and optional salt.
    20	 * 2. HKDF-Expand: expand the pseudorandom key into output keying material of
    21	 *    any length, parameterized by an application-specific info string.
    22	 *
    23	 */
    24	
    25	/* HKDF-Extract (RFC 5869 section 2.2), unsalted */
  > 26	int hkdf_extract(struct crypto_shash *hmac_tfm, const u8 *ikm,
    27			 unsigned int ikmlen, u8 *prk)
    28	{
    29		unsigned int prklen = crypto_shash_digestsize(hmac_tfm);
    30		u8 *default_salt;
    31		int err;
    32	
    33		default_salt = kzalloc(prklen, GFP_KERNEL);
    34		if (!default_salt)
    35			return -ENOMEM;
    36		err = crypto_shash_setkey(hmac_tfm, default_salt, prklen);
    37		if (!err)
    38			err = crypto_shash_tfm_digest(hmac_tfm, ikm, ikmlen, prk);
    39	
    40		kfree(default_salt);
    41		return err;
    42	}
    43	EXPORT_SYMBOL_GPL(hkdf_extract);
    44	
    45	/*
    46	 * HKDF-Expand (RFC 5869 section 2.3).
    47	 * This expands the pseudorandom key, which was already keyed into @hmac_tfm,
    48	 * into @okmlen bytes of output keying material parameterized by the
    49	 * application-specific @info of length @infolen bytes.
    50	 * This is thread-safe and may be called by multiple threads in parallel.
    51	 */
  > 52	int hkdf_expand(struct crypto_shash *hmac_tfm,

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