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vhost: make page logging atomic

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Each dirty page logging operation should be atomic. But it's not
atomic in current implementation. So it's possible that some dirty
pages can't be logged successfully when different threads try to
log different pages into the same byte of the log buffer concurrently.
This patch fixes this issue.

Fixes: b171fad1ff ("vhost: log used vring changes")
Cc: stable@dpdk.org

Reported-by: Xiao Wang <xiao.w.wang@intel.com>
Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
This commit is contained in:
Tiwei Bie 2017-08-01 17:01:21 +08:00 committed by Thomas Monjalon
parent 7b681637d2
commit 897f13a1f7
1 changed files with 10 additions and 1 deletions
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11
lib/librte_vhost/vhost.h
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@ -201,10 +201,19 @@ struct virtio_net {
#define VHOST_LOG_PAGE 4096
/*
* Atomically set a bit in memory.
*/
static __rte_always_inline void
vhost_set_bit(unsigned int nr, volatile uint8_t *addr)
{
__sync_fetch_and_or_8(addr, (1U << nr));
}
static __rte_always_inline void
vhost_log_page(uint8_t *log_base, uint64_t page)
{
log_base[page / 8] |= 1 << (page % 8);
vhost_set_bit(page % 8, &log_base[page / 8]);
}
static __rte_always_inline void