From: Jens Axboe <[email protected]> gsource_check() only looks at the ppoll revents for the io_uring fd, but CQEs can be posted during gsource_prepare()'s io_uring_submit() call via kernel task_work processing on syscall exit. These completions are already sitting in the CQ ring but the ring fd may not be signaled yet, causing gsource_check() to return false.
Add a fallback io_uring_cq_ready() check so completions that arrive during submission are dispatched immediately rather than waiting for the next ppoll() cycle. Signed-off-by: Jens Axboe <[email protected]> Message-ID: <[email protected]> Signed-off-by: Stefan Hajnoczi <[email protected]> --- util/fdmon-io_uring.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/util/fdmon-io_uring.c b/util/fdmon-io_uring.c index d0b56127c6..b81e412402 100644 --- a/util/fdmon-io_uring.c +++ b/util/fdmon-io_uring.c @@ -344,7 +344,19 @@ static void fdmon_io_uring_gsource_prepare(AioContext *ctx) static bool fdmon_io_uring_gsource_check(AioContext *ctx) { gpointer tag = ctx->io_uring_fd_tag; - return g_source_query_unix_fd(&ctx->source, tag) & G_IO_IN; + + /* Check ppoll revents (normal path) */ + if (g_source_query_unix_fd(&ctx->source, tag) & G_IO_IN) { + return true; + } + + /* + * Also check for CQEs that may have been posted during prepare's + * io_uring_submit() via task_work on syscall exit. Without this, + * the main loop can miss completions and sleep in ppoll() until the + * next timer fires. + */ + return io_uring_cq_ready(&ctx->fdmon_io_uring); } /* Dispatch CQE handlers that are ready */ -- 2.53.0
