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    Subject[PATCH 4.9 29/62] s390/uaccess: avoid (false positive) compiler warnings
    Date
    From: Christian Borntraeger <borntraeger@de.ibm.com>

    [ Upstream commit 062795fcdcb2d22822fb42644b1d76a8ad8439b3 ]

    Depending on inlining decisions by the compiler, __get/put_user_fn
    might become out of line. Then the compiler is no longer able to tell
    that size can only be 1,2,4 or 8 due to the check in __get/put_user
    resulting in false positives like

    ./arch/s390/include/asm/uaccess.h: In function ‘__put_user_fn’:
    ./arch/s390/include/asm/uaccess.h:113:9: warning: ‘rc’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    113 | return rc;
    | ^~
    ./arch/s390/include/asm/uaccess.h: In function ‘__get_user_fn’:
    ./arch/s390/include/asm/uaccess.h:143:9: warning: ‘rc’ may be used uninitialized in this function [-Wmaybe-uninitialized]
    143 | return rc;
    | ^~

    These functions are supposed to be always inlined. Mark it as such.

    Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
    Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/s390/include/asm/uaccess.h | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
    index a7ef702201260..31b2913372b56 100644
    --- a/arch/s390/include/asm/uaccess.h
    +++ b/arch/s390/include/asm/uaccess.h
    @@ -151,7 +151,7 @@ unsigned long __must_check __copy_to_user(void __user *to, const void *from,
    __rc; \
    })

    -static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
    +static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
    {
    unsigned long spec = 0x810000UL;
    int rc;
    @@ -181,7 +181,7 @@ static inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)
    return rc;
    }

    -static inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
    +static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsigned long size)
    {
    unsigned long spec = 0x81UL;
    int rc;
    --
    2.20.1


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