RE: [PATCH 14/34] PCI: hv: switch hv_get_dom_num() to use atomic find_bit()

[Michael Kelley]

From: Yury Norov <yury.norov@xxxxxxxxx> Sent: Saturday, November 18, 2023 7:51 AM
> 
> The function traverses bitmap with for_each_clear_bit() just to allocate
> a bit atomically. We can do it better with a dedicated find_and_set_bit().
> 
> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
> ---
>  drivers/pci/controller/pci-hyperv.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-
> hyperv.c
> index 30c7dfeccb16..033b1fb7f4eb 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -3605,12 +3605,9 @@ static u16 hv_get_dom_num(u16 dom)
>  	if (test_and_set_bit(dom, hvpci_dom_map) == 0)
>  		return dom;
> 
> -	for_each_clear_bit(i, hvpci_dom_map, HVPCI_DOM_MAP_SIZE) {
> -		if (test_and_set_bit(i, hvpci_dom_map) == 0)
> -			return i;
> -	}
> +	i = find_and_set_bit(hvpci_dom_map, HVPCI_DOM_MAP_SIZE);
> 
> -	return HVPCI_DOM_INVALID;
> +	return i < HVPCI_DOM_MAP_SIZE ? i : HVPCI_DOM_INVALID;
>  }
> 
>  /**
> --
> 2.39.2

Reviewed-by: Michael Kelley <mhklinux@xxxxxxxxxxx>