Add regression test case for task_work regression

Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 133 insertions, 2 deletions

diff --git a/test/Makefile b/test/Makefile
index c80ad42..2d71db0 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -25,7 +25,7 @@ all_targets += poll poll-cancel ring-leak fsync io_uring_setup io_uring_register
 		short-read openat2 probe shared-wq personality eventfd \
 		send_recv eventfd-ring across-fork sq-poll-kthread splice \
 		lfs-openat lfs-openat-write iopoll d4ae271dfaae-test \
-		eventfd-disable close-opath
+		eventfd-disable close-opath ce593a6c480a-test
 
 include ../Makefile.quiet
 
@@ -65,7 +65,7 @@ test_srcs := poll.c poll-cancel.c ring-leak.c fsync.c io_uring_setup.c \
 	madvise.c short-read.c openat2.c probe.c shared-wq.c \
 	personality.c eventfd.c eventfd-ring.c across-fork.c sq-poll-kthread.c \
 	splice.c lfs-openat.c lfs-openat-write.c iopoll.c d4ae271dfaae-test.c \
-	eventfd-disable.c close-opath.c
+	eventfd-disable.c close-opath.c ce593a6c480a-test.c
 
 ifdef CONFIG_HAVE_STATX
 test_srcs += statx.c
@@ -86,6 +86,7 @@ accept-link: XCFLAGS = -lpthread
 submit-reuse: XCFLAGS = -lpthread
 poll-v-poll: XCFLAGS = -lpthread
 across-fork: XCFLAGS = -lpthread
+ce593a6c480a-test: XCFLAGS = -lpthread
 
 install: $(all_targets) runtests.sh runtests-loop.sh
 	$(INSTALL) -D -d -m 755 $(datadir)/liburing-test/
diff --git a/test/ce593a6c480a-test.c b/test/ce593a6c480a-test.c
new file mode 100644
index 0000000..8763893
--- /dev/null
+++ b/test/ce593a6c480a-test.c
@@ -0,0 +1,130 @@
+/*
+ * Test 5.7 regression with task_work not being run while a task is
+ * waiting on another event in the kernel.
+ */
+#include <errno.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/eventfd.h>
+#include <unistd.h>
+#include <pthread.h>
+#include "liburing.h"
+
+static int use_sqpoll = 0;
+
+void notify_fd(int fd)
+{
+	char buf[8] = {0, 0, 0, 0, 0, 0, 1};
+	int ret;
+
+	ret = write(fd, &buf, 8);
+	if (ret < 0)
+		perror("write");
+}
+
+void *delay_set_fd_from_thread(void *data)
+{
+	int fd = (intptr_t) data;
+
+	sleep(1);
+	notify_fd(fd);
+	return NULL;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring_params p = {};
+	struct io_uring ring;
+	int loop_fd, other_fd;
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe = NULL;
+	int ret, use_fd;
+	char buf[8] = {0, 0, 0, 0, 0, 0, 1};
+	pthread_t tid;
+
+	/* Create an eventfd to be registered with the loop to be
+	 * notified of events being ready
+	 */
+	loop_fd = eventfd(0, EFD_CLOEXEC);
+	if (loop_fd == -1) {
+		fprintf(stderr, "eventfd errno=%d\n", errno);
+		return 1;
+	}
+
+	/* Create an eventfd that can create events */
+	use_fd = other_fd = eventfd(0, EFD_CLOEXEC);
+	if (other_fd == -1) {
+		fprintf(stderr, "eventfd errno=%d\n", errno);
+		return 1;
+	}
+
+	if (use_sqpoll)
+		p.flags = IORING_SETUP_SQPOLL;
+
+	/* Setup the ring with a registered event fd to be notified on events */
+	ret = io_uring_queue_init_params(8, &ring, &p);
+	if (ret) {
+		fprintf(stderr, "queue_init=%d\n", ret);
+		return 1;
+	}
+	ret = io_uring_register_eventfd(&ring, loop_fd);
+	if (ret < 0) {
+		fprintf(stderr, "register_eventfd=%d\n", ret);
+		return 1;
+	}
+
+	if (use_sqpoll) {
+		ret = io_uring_register_files(&ring, &other_fd, 1);
+		if (ret < 0) {
+			fprintf(stderr, "register_files=%d\n", ret);
+			return 1;
+		}
+		use_fd = 0;
+	}
+
+	/* Submit a poll operation to wait on an event in other_fd */
+	sqe = io_uring_get_sqe(&ring);
+	io_uring_prep_poll_add(sqe, use_fd, POLLIN);
+	sqe->user_data = 1;
+	if (use_sqpoll)
+		sqe->flags |= IOSQE_FIXED_FILE;
+	ret = io_uring_submit(&ring);
+	if (ret != 1) {
+		fprintf(stderr, "submit=%d\n", ret);
+		return 1;
+	}
+
+	/*
+	 * CASE 3: Hangs forever in Linux 5.7.5; Works in Linux 5.6.0 When this
+	 * code is uncommented, we don't se a notification on other_fd until
+	 * _after_ we have started the read on loop_fd. In that case, the read() on
+	 * loop_fd seems to hang forever.
+	*/
+    	pthread_create(&tid, NULL, delay_set_fd_from_thread,
+			(void*) (intptr_t) other_fd);
+
+	/* Wait on the event fd for an event to be ready */
+	ret = read(loop_fd, buf, 8);
+	if (ret < 0) {
+		perror("read");
+		return 1;
+	} else if (ret != 8) {
+		fprintf(stderr, "Odd-sized eventfd read: %d\n", ret);
+		return 1;
+	}
+
+
+	ret = io_uring_wait_cqe(&ring, &cqe);
+	if (ret) {
+		fprintf(stderr, "wait_cqe=%d\n", ret);
+		return ret;
+	}
+	if (cqe->res < 0) {
+		fprintf(stderr, "cqe->res=%d\n", cqe->res);
+		return 1;
+	}
+
+	io_uring_cqe_seen(&ring, cqe);
+	return 0;
+}