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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>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Natanael Copa 2014-04-29 16:17:29 +02:00 committed by Peter Maydell
parent adf9d70b0d
commit 747eb78baa
1 changed files with 2 additions and 4 deletions
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6
hw/virtio/vhost.c
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@ -41,7 +41,6 @@ static void vhost_dev_sync_region(struct vhost_dev *dev,
for (;from < to; ++from) { for (;from < to; ++from) {
vhost_log_chunk_t log; vhost_log_chunk_t log;
int bit;
/* We first check with non-atomic: much cheaper, /* We first check with non-atomic: much cheaper,
* and we expect non-dirty to be the common case. */ * and we expect non-dirty to be the common case. */
if (!*from) { 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 /* Data must be read atomically. We don't really need barrier semantics
* but it's easier to use atomic_* than roll our own. */ * but it's easier to use atomic_* than roll our own. */
log = atomic_xchg(from, 0); log = atomic_xchg(from, 0);
while ((bit = sizeof(log) > sizeof(int) ? while (log) {
ffsll(log) : ffs(log))) { int bit = ctzl(log);
hwaddr page_addr; hwaddr page_addr;
hwaddr section_offset; hwaddr section_offset;
hwaddr mr_offset; hwaddr mr_offset;
bit -= 1;
page_addr = addr + bit * VHOST_LOG_PAGE; page_addr = addr + bit * VHOST_LOG_PAGE;
section_offset = page_addr - section->offset_within_address_space; section_offset = page_addr - section->offset_within_address_space;
mr_offset = section_offset + section->offset_within_region; mr_offset = section_offset + section->offset_within_region;