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linux: Fix missing memory barrier between updating SQ tail and reading SQ flags

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Link: https://github.com/libuv/libuv/pull/3952#discussion_r2482158152
Signed-off-by: hev <git@hev.cc>
This commit is contained in:
hev 2025-11-03 00:52:56 +08:00
parent 12d1ed1380
commit 5c65e12a50
1 changed files with 4 additions and 11 deletions
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15
src/unix/linux.c
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@ -807,16 +807,12 @@ static struct uv__io_uring_sqe* uv__iou_get_sqe(struct uv__iou* iou,
static void uv__iou_submit(struct uv__iou* iou) {
uint32_t flags;
atomic_store_explicit((_Atomic uint32_t*) iou->sqtail,
*iou->sqtail + 1,
memory_order_release);
atomic_thread_fence(memory_order_seq_cst);
flags = atomic_load_explicit((_Atomic uint32_t*) iou->sqflags,
memory_order_acquire);
if (flags & UV__IORING_SQ_NEED_WAKEUP)
if (*iou->sqflags & UV__IORING_SQ_NEED_WAKEUP)
if (uv__io_uring_enter(iou->ringfd, 0, 0, UV__IORING_ENTER_SQ_WAKEUP))
if (errno != EOWNERDEAD) /* Kernel bug. Harmless, ignore. */
perror("libuv: io_uring_enter(wakeup)"); /* Can't happen. */
@ -1167,7 +1163,6 @@ static void uv__poll_io_uring(uv_loop_t* loop, struct uv__iou* iou) {
uint32_t tail;
uint32_t mask;
uint32_t i;
uint32_t flags;
int nevents;
int rc;
@ -1214,14 +1209,12 @@ static void uv__poll_io_uring(uv_loop_t* loop, struct uv__iou* iou) {
atomic_store_explicit((_Atomic uint32_t*) iou->cqhead,
tail,
memory_order_release);
atomic_thread_fence(memory_order_seq_cst);
/* Check whether CQE's overflowed, if so enter the kernel to make them
* available. Don't grab them immediately but in the next loop iteration to
* avoid loop starvation. */
flags = atomic_load_explicit((_Atomic uint32_t*) iou->sqflags,
memory_order_acquire);
if (flags & UV__IORING_SQ_CQ_OVERFLOW) {
if (*iou->sqflags & UV__IORING_SQ_CQ_OVERFLOW) {
do
rc = uv__io_uring_enter(iou->ringfd, 0, 0, UV__IORING_ENTER_GETEVENTS);
while (rc == -1 && errno == EINTR);