io_uring: add 'cq_flags' field for the CQ ring
This patch adds the new 'cq_flags' field that should be written by
the application and read by the kernel.
This new field is available to the userspace application through
'cq_off.flags'.
We are using 4-bytes previously reserved and set to zero. This means
that if the application finds this field to zero, then the new
functionality is not supported.
In the next patch we will introduce the first flag available.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9820668..0225069 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -142,7 +142,7 @@ struct io_rings {
*/
u32 sq_dropped;
/*
- * Runtime flags
+ * Runtime SQ flags
*
* Written by the kernel, shouldn't be modified by the
* application.
@@ -152,6 +152,13 @@ struct io_rings {
*/
u32 sq_flags;
/*
+ * Runtime CQ flags
+ *
+ * Written by the application, shouldn't be modified by the
+ * kernel.
+ */
+ u32 cq_flags;
+ /*
* Number of completion events lost because the queue was full;
* this should be avoided by the application by making sure
* there are not more requests pending than there is space in
@@ -7930,6 +7937,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
p->cq_off.cqes = offsetof(struct io_rings, cqes);
+ p->cq_off.flags = offsetof(struct io_rings, cq_flags);
p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
