@@ -241,14 +241,14 @@ only the
passthrough command for NVMe passthrough needs this. Available since 5.19.
.TP
.B IORING_SETUP_SINGLE_ISSUER
-A hint to the kernel that only a single task can submit requests, which is used
-for internal optimisations. The kernel enforces the rule, which only affects
+A hint to the kernel that only a single task (or thread) will submit requests, which is
+used for internal optimisations. This task must be the one that created the ring, and
+the kernel enforces this rule. This only affects
.I
io_uring_enter(2)
calls submitting requests and will fail them with
.B -EEXIST
if the restriction is violated.
-The submitter task may differ from the task that created the ring.
Note that when
.B IORING_SETUP_SQPOLL
is set it is considered that the polling task is doing all submissions
@@ -256,7 +256,7 @@ on behalf of the userspace and so it always complies with the rule disregarding
how many userspace tasks do
.I
io_uring_enter(2).
-Available since 5.20.
+Available since 6.0.
.TP
.B IORING_SETUP_DEFER_TASKRUN
By default, io_uring will process all outstanding work at the end of any system
@@ -123,6 +123,9 @@ void *thread(void *t)
{
struct thread_data *td = t;
+ assert(io_uring_queue_init(8, &td->ring, IORING_SETUP_SINGLE_ISSUER |
+ IORING_SETUP_DEFER_TASKRUN) == 0);
+
io_uring_prep_read(io_uring_get_sqe(&td->ring), td->efd, td->buff, sizeof(td->buff), 0);
io_uring_submit(&td->ring);
@@ -132,23 +135,16 @@ void *thread(void *t)
static int test_thread_shutdown(void)
{
pthread_t t1;
- int ret;
struct thread_data td;
struct io_uring_cqe *cqe;
uint64_t val = 1;
- ret = io_uring_queue_init(8, &td.ring, IORING_SETUP_SINGLE_ISSUER |
- IORING_SETUP_DEFER_TASKRUN);
- if (ret)
- return ret;
-
- CHECK(io_uring_get_events(&td.ring) == -EEXIST);
-
td.efd = eventfd(0, 0);
CHECK(td.efd >= 0);
CHECK(pthread_create(&t1, NULL, thread, &td) == 0);
CHECK(pthread_join(t1, NULL) == 0);
+ CHECK(io_uring_get_events(&td.ring) == -EEXIST);
CHECK(write(td.efd, &val, sizeof(val)) == sizeof(val));
CHECK(io_uring_wait_cqe(&td.ring, &cqe) == -EEXIST);
@@ -96,7 +96,7 @@ int main(int argc, char *argv[])
if (!fork_t()) {
ret = try_submit(&ring);
if (ret != -EEXIST)
- fprintf(stderr, "not owner child could submit %i\n", ret);
+ fprintf(stderr, "1: not owner child could submit %i\n", ret);
return ret != -EEXIST;
}
wait_child_t();
@@ -109,9 +109,9 @@ int main(int argc, char *argv[])
if (!fork_t()) {
ret = try_submit(&ring);
- if (ret)
- fprintf(stderr, "not owner child could submit %i\n", ret);
- return !!ret;
+ if (ret != -EEXIST)
+ fprintf(stderr, "2: not owner child could submit %i\n", ret);
+ return ret != -EEXIST;
}
wait_child_t();
io_uring_queue_exit(&ring);
@@ -143,9 +143,9 @@ int main(int argc, char *argv[])
if (!fork_t()) {
ret = try_submit(&ring);
- if (ret)
- fprintf(stderr, "not owner child could submit %i\n", ret);
- return !!ret;
+ if (ret != -EEXIST)
+ fprintf(stderr, "3: not owner child could submit %i\n", ret);
+ return ret != -EEXIST;
}
wait_child_t();
io_uring_queue_exit(&ring);
IORING_SETUP_SINGLE_ISSUER now registers the task at ring creation, so update the tests and documentation to reflect this. Signed-off-by: Dylan Yudaken <dylany@fb.com> --- man/io_uring_setup.2 | 8 ++++---- test/defer-taskrun.c | 12 ++++-------- test/single-issuer.c | 14 +++++++------- 3 files changed, 15 insertions(+), 19 deletions(-)