From 897f13a1f726cefdc68762da83f9d2225a85c27e Mon Sep 17 00:00:00 2001 From: Tiwei Bie Date: Tue, 1 Aug 2017 17:01:21 +0800 Subject: [PATCH] vhost: make page logging atomic 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: b171fad1ffa5 ("vhost: log used vring changes") Cc: stable@dpdk.org Reported-by: Xiao Wang Signed-off-by: Tiwei Bie Reviewed-by: Maxime Coquelin --- lib/librte_vhost/vhost.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index 0f294f3959..6fe72aeb61 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -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 -- 2.20.1