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Message-ID: <SN6PR02MB4157D60D59F2461BB595F569D4B6A@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Sat, 18 Nov 2023 17:59:13 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Yury Norov <yury.norov@...il.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"K. Y. Srinivasan" <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof WilczyĆski <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
CC: Jan Kara <jack@...e.cz>,
Mirsad Todorovac <mirsad.todorovac@....unizg.hr>,
Matthew Wilcox <willy@...radead.org>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Maxim Kuvyrkov <maxim.kuvyrkov@...aro.org>,
Alexey Klimov <klimov.linux@...il.com>
Subject: RE: [PATCH 14/34] PCI: hv: switch hv_get_dom_num() to use atomic
find_bit()
From: Yury Norov <yury.norov@...il.com> 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@...il.com>
> ---
> 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@...look.com>
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