tree 75a404f14c2eb3a774adda0364b649ea2e4c39da
parent b2af35a8ab42d54e996f5678c63e490461bffc4e
author Nathan Chancellor <natechancellor@gmail.com> 1558714517 -0700
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1580289865 +0100

misc: sgi-xp: Properly initialize buf in xpc_get_rsvd_page_pa

[ Upstream commit b0576f9ecb5c51e9932531d23c447b2739261841 ]

Clang warns:

drivers/misc/sgi-xp/xpc_partition.c:73:14: warning: variable 'buf' is
uninitialized when used within its own initialization [-Wuninitialized]
        void *buf = buf;
              ~~~   ^~~
1 warning generated.

Arnd's explanation during review:

  /*
   * Returns the physical address of the partition's reserved page through
   * an iterative number of calls.
   *
   * On first call, 'cookie' and 'len' should be set to 0, and 'addr'
   * set to the nasid of the partition whose reserved page's address is
   * being sought.
   * On subsequent calls, pass the values, that were passed back on the
   * previous call.
   *
   * While the return status equals SALRET_MORE_PASSES, keep calling
   * this function after first copying 'len' bytes starting at 'addr'
   * into 'buf'. Once the return status equals SALRET_OK, 'addr' will
   * be the physical address of the partition's reserved page. If the
   * return status equals neither of these, an error as occurred.
   */
  static inline s64
  sn_partition_reserved_page_pa(u64 buf, u64 *cookie, u64 *addr, u64 *len)

  so *len is set to zero on the first call and tells the bios how many
  bytes are accessible at 'buf', and it does get updated by the BIOS to
  tell us how many bytes it needs, and then we allocate that and try again.

Fixes: 279290294662 ("[IA64-SGI] cleanup the way XPC locates the reserved page")
Link: https://github.com/ClangBuiltLinux/linux/issues/466
Suggested-by: Stephen Hines <srhines@google.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>