From: Dharanitharan R <dharanitharan725@gmail.com>
To: gregkh@linuxfoundation.org
Cc: linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org,
Dharanitharan R <dharanitharan725@gmail.com>,
David Laight <david.laight.linux@gmail.com>
Subject: [PATCH v2] staging: vme_user: simplify bus number allocation using ffz()
Date: Sun, 7 Dec 2025 16:43:17 +0000 [thread overview]
Message-ID: <20251207164317.4835-1-dharanitharan725@gmail.com> (raw)
David Laight pointed out that the loop in vme_register_bridge()
is effectively searching for the first zero bit in vme_bus_numbers.
Replace the manual loop with ffz() and use BIT(n) for consistency.
Suggested-by: David Laight <david.laight.linux@gmail.com>
Signed-off-by: Dharanitharan R <dharanitharan725@gmail.com>
---
drivers/staging/vme_user/vme.c | 15 +++++++++++++----------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/vme_user/vme.c b/drivers/staging/vme_user/vme.c
index 2095de72596a..45381e677475 100644
--- a/drivers/staging/vme_user/vme.c
+++ b/drivers/staging/vme_user/vme.c
@@ -1765,16 +1765,19 @@ int vme_register_bridge(struct vme_bridge *bridge)
int ret = -1;
mutex_lock(&vme_buses_lock);
- for (i = 0; i < sizeof(vme_bus_numbers) * 8; i++){
- if ((vme_bus_numbers & (1 << i)) == 0) {
- vme_bus_numbers |= (1 << i);
- bridge->num = i;
- INIT_LIST_HEAD(&bridge->devices);
- list_add_tail(&bridge->bus_list, &vme_bus_list);
- ret = 0;
- break;
- }
+
+ /* Find the first clear bit */
+ i = ffz(vme_bus_numbers);
+
+ /* Ensure we have a free slot */
+ if (i < BITS_PER_LONG) {
+ vme_bus_numbers |= BIT(i);
+ bridge->num = i;
+ INIT_LIST_HEAD(&bridge->devices);
+ list_add_tail(&bridge->bus_list, &vme_bus_list);
+ ret = 0;
+ }
mutex_unlock(&vme_buses_lock);
return ret;
@@ -1787,7 +1790,7 @@ void vme_unregister_bridge(struct vme_bridge *bridge)
struct vme_dev *tmp;
mutex_lock(&vme_buses_lock);
- vme_bus_numbers &= ~(1 << bridge->num);
+ vme_bus_numbers &= ~BIT(bridge->num);
list_for_each_entry_safe(vdev, tmp, &bridge->devices, bridge_list) {
list_del(&vdev->drv_list);
list_del(&vdev->bridge_list);
--
2.43.0
next reply other threads:[~2025-12-07 16:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-07 16:43 Dharanitharan R [this message]
2025-12-07 17:50 ` [PATCH v2] staging: vme_user: simplify bus number allocation using ffz() David Laight
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