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    IB/mlx5: avoid bogus -Wmaybe-uninitialized warning · 14ab8896
    Arnd Bergmann 提交于
    We get a false-positive warning in linux-next for the mlx5 driver:
    
    infiniband/hw/mlx5/mr.c: In function ‘mlx5_ib_reg_user_mr’:
    infiniband/hw/mlx5/mr.c:1172:5: error: ‘order’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
    infiniband/hw/mlx5/mr.c:1161:6: note: ‘order’ was declared here
    infiniband/hw/mlx5/mr.c:1173:6: error: ‘ncont’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
    infiniband/hw/mlx5/mr.c:1160:6: note: ‘ncont’ was declared here
    infiniband/hw/mlx5/mr.c:1173:6: error: ‘page_shift’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
    infiniband/hw/mlx5/mr.c:1158:6: note: ‘page_shift’ was declared here
    infiniband/hw/mlx5/mr.c:1143:13: error: ‘npages’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
    infiniband/hw/mlx5/mr.c:1159:6: note: ‘npages’ was declared here
    
    I had a trivial workaround for gcc-5 or higher, but that didn't work
    on gcc-4.9 unfortunately.
    
    The only way I found to avoid the warnings for gcc-4.9, short of
    initializing each of the arguments first was to change the calling
    conventions to separate the error code from the umem pointer. This
    avoids casting the error codes from one pointer to another incompatible
    pointer, and lets gcc figure out when that the data is actually valid
    whenever we return successfully.
    Acked-by: NLeon Romanovsky <leonro@mellanox.com>
    Signed-off-by: NArnd Bergmann <arnd@arndb.de>
    Signed-off-by: NDoug Ledford <dledford@redhat.com>
    14ab8896
mr.c 45.1 KB