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    Subject[PATCHv4 07/18] atomics: prepare for atomic64_fetch_add_unless()
    Date
    Currently all architectures must implement atomic_fetch_add_unless(),
    with common code providing atomic_add_unless(). Architectures must also
    implement atomic64_add_unless() directly, with no corresponding
    atomic64_fetch_add_unless().

    This divergence is unfortunate, and means that the APIs for atomic_t,
    atomic64_t, and atomic_long_t differ.

    In preparation for unifying things, with architectures providing
    atomic64_fetch_add_unless, this patch adds a generic
    atomic64_add_unless() which will use atomic64_fetch_add_unless(). The
    instrumented atomics are updated to take this case into account.

    There should be no functional change as a result of this patch.

    Signed-off-by: Mark Rutland <mark.rutland@arm.com>
    Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Reviewed-by: Will Deacon <will.deacon@arm.com>
    Cc: Boqun Feng <boqun.feng@gmail.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Richard Henderson <rth@twiddle.net>
    Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    Cc: Matt Turner <mattst88@gmail.com>
    Cc: Vineet Gupta <vgupta@synopsys.com>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Palmer Dabbelt <palmer@sifive.com>
    Cc: Albert Ou <albert@sifive.com>
    ---
    include/asm-generic/atomic-instrumented.h | 9 +++++++++
    include/linux/atomic.h | 16 ++++++++++++++++
    2 files changed, 25 insertions(+)

    diff --git a/include/asm-generic/atomic-instrumented.h b/include/asm-generic/atomic-instrumented.h
    index 1f9b2a767d3c..444bf2f9d54d 100644
    --- a/include/asm-generic/atomic-instrumented.h
    +++ b/include/asm-generic/atomic-instrumented.h
    @@ -93,11 +93,20 @@ static __always_inline int atomic_fetch_add_unless(atomic_t *v, int a, int u)
    }
    #endif

    +#ifdef arch_atomic64_fetch_add_unless
    +#define atomic64_fetch_add_unless atomic64_fetch_add_unless
    +static __always_inline s64 atomic64_fetch_add_unless(atomic64_t *v, s64 a, s64 u)
    +{
    + kasan_check_write(v, sizeof(*v));
    + return arch_atomic64_fetch_add_unless(v, a, u);
    +}
    +#else
    static __always_inline bool atomic64_add_unless(atomic64_t *v, s64 a, s64 u)
    {
    kasan_check_write(v, sizeof(*v));
    return arch_atomic64_add_unless(v, a, u);
    }
    +#endif

    static __always_inline void atomic_inc(atomic_t *v)
    {
    diff --git a/include/linux/atomic.h b/include/linux/atomic.h
    index b89ba36cab94..3c03de648007 100644
    --- a/include/linux/atomic.h
    +++ b/include/linux/atomic.h
    @@ -1043,6 +1043,22 @@ static inline int atomic_dec_if_positive(atomic_t *v)
    #endif /* atomic64_try_cmpxchg */

    /**
    + * atomic64_add_unless - add unless the number is already a given value
    + * @v: pointer of type atomic_t
    + * @a: the amount to add to v...
    + * @u: ...unless v is equal to u.
    + *
    + * Atomically adds @a to @v, if @v was not already @u.
    + * Returns true if the addition was done.
    + */
    +#ifdef atomic64_fetch_add_unless
    +static inline bool atomic64_add_unless(atomic64_t *v, long long a, long long u)
    +{
    + return atomic64_fetch_add_unless(v, a, u) != u;
    +}
    +#endif
    +
    +/**
    * atomic64_inc_not_zero - increment unless the number is zero
    * @v: pointer of type atomic64_t
    *
    --
    2.11.0
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