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From f5fba0976a2841e2f4033a01076161ce2ede0477 Mon Sep 17 00:00:00 2001
From: Natanael Copa <ncopa@alpinelinux.org>
Date: Tue, 29 Apr 2014 14:34:12 +0200
Subject: [PATCH 4/6] vhost: replace ffsl with ctzl
Avoid using the GNU extesion ffsl which is not implemented in musl libc.
The atomic_xchg() means we know that vhost_log_chunk_t will never be
larger than the 'long' type, so ctzl() is always sufficient.
See also commit fbeadf50 (bitops: unify bitops_ffsl with the one in
host-utils.h, call it bitops_ctzl) on why ctzl should be used instead
of ffsl.
Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
---
hw/virtio/vhost.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 9e336ad..f62cfaf 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -41,7 +41,6 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
for (;from < to; ++from) {
vhost_log_chunk_t log;
- int bit;
/* We first check with non-atomic: much cheaper,
* and we expect non-dirty to be the common case. */
if (!*from) {
@@ -51,12 +50,11 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
/* Data must be read atomically. We don't really need barrier semantics
* but it's easier to use atomic_* than roll our own. */
log = atomic_xchg(from, 0);
- while ((bit = sizeof(log) > sizeof(int) ?
- ffsll(log) : ffs(log))) {
+ while (log) {
+ int bit = ctzl(log);
hwaddr page_addr;
hwaddr section_offset;
hwaddr mr_offset;
- bit -= 1;
page_addr = addr + bit * VHOST_LOG_PAGE;
section_offset = page_addr - section->offset_within_address_space;
mr_offset = section_offset + section->offset_within_region;
--
1.9.2
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