Re: [Qemu-devel] [PATCH v0 2/7] bitops: add some atomic versions of bitmap operations

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Denis Plotnikov (dplotnikov@virtuozzo.com) wrote:
> 1. test bit
> 2. test and set bit
> 
> Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
> ---
>  include/qemu/bitops.h | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
> index 3f0926cf40..7b1c8c7baf 100644
> --- a/include/qemu/bitops.h
> +++ b/include/qemu/bitops.h
> @@ -94,6 +94,21 @@ static inline int test_and_set_bit(long nr, unsigned long *addr)
>      return (old & mask) != 0;
>  }
>  
> +/**
> + * test_and_set_bit_atomic - Set a bit atomically and return its old value
> + * @nr: Bit to set
> + * @addr: Address to count from
> + */
> +static inline int test_and_set_bit_atomic(long nr, unsigned long *addr)
> +{
> +    unsigned long mask = BIT_MASK(nr);
> +    unsigned long *p = addr + BIT_WORD(nr);
> +    unsigned long old;
> +
> +    old = atomic_fetch_or(p, mask);
> +    return (old & mask) != 0;
> +}
> +
>  /**
>   * test_and_clear_bit - Clear a bit and return its old value
>   * @nr: Bit to clear
> @@ -134,6 +149,15 @@ static inline int test_bit(long nr, const unsigned long *addr)
>      return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
>  }
>  
> +/**
> + * test_bit_atomic - Determine whether a bit is set atomicallly
> + * @nr: bit number to test
> + * @addr: Address to start counting from
> + */
> +static inline int test_bit_atomic(long nr, const unsigned long *addr)
> +{
> +    return 1UL & (atomic_read(&addr[BIT_WORD(nr)]) >> (nr & (BITS_PER_LONG-1)));

Note that fails the style check because it's expecting spaces around the
'-', (which would then take you over 80 chars);  your patch is
consistent with the other places in the file though.
It's probably best if you make the style checker happy.

So,

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> +}
>  /**
>   * find_last_bit - find the last set bit in a memory region
>   * @addr: The address to start the search at
> -- 
> 2.17.0
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK