[PATCH v4 14/40] PCI: hv: Optimize hv_get_dom_num() by using find_and_set_bit()

Yury Norov
2024-06-20T17:57:49Z

The function traverses bitmap with for_each_clear_bit() just to allocate
a bit atomically. Simplify it by using dedicated find_and_set_bit().

Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/controller/pci-hyperv.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 5992280e8110..d8a3ca9a7378 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -37,6 +37,7 @@
* the PCI back-end driver in Hyper-V.
*/

+#include <linux/find_atomic.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
@@ -3599,12 +3600,9 @@ 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;
}

/**
--
2.43.0