[PATCH 4/4] io_uring: only !null ptr to io_issue_sqe()

Pavel Begunkov
2019-11-21T20:21:43Z

Pass only non-null @nxt to io_issue_sqe() and handle it at the caller's
side. And propagate it.

- kiocb_done() is only called from io_read() and io_write(), which are
only called from io_issue_sqe(), so it's @nxt != NULL

- io_put_req_find_next() is called either with explicitly non-null local
nxt, or from one of the functions in io_issue_sqe() switch (or their
callees).

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1ab045e5d663..3e8efe8f064d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -985,21 +985,13 @@ static void io_free_req(struct io_kiocb *req)
* Drop reference to request, return next in chain (if there is one) if this
* was the last reference to this request.
*/
+__attribute__((nonnull))
static void io_put_req_find_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
{
- struct io_kiocb *nxt = NULL;
-
- io_req_find_next(req, &nxt);
+ io_req_find_next(req, nxtptr);

if (refcount_dec_and_test(&req->refs))
__io_free_req(req);
-
- if (nxt) {
- if (nxtptr)
- *nxtptr = nxt;
- else
- io_queue_async_work(nxt);
- }
}

static void io_put_req(struct io_kiocb *req)
@@ -1482,7 +1474,7 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
static void kiocb_done(struct kiocb *kiocb, ssize_t ret, struct io_kiocb **nxt,
bool in_async)
{
- if (in_async && ret >= 0 && nxt && kiocb->ki_complete == io_complete_rw)
+ if (in_async && ret >= 0 && kiocb->ki_complete == io_complete_rw)
*nxt = __io_complete_rw(kiocb, ret);
else
io_rw_done(kiocb, ret);
@@ -2570,6 +2562,7 @@ static int io_req_defer(struct io_kiocb *req)
return -EIOCBQUEUED;
}

+__attribute__((nonnull))
static int io_issue_sqe(struct io_kiocb *req, struct io_kiocb **nxt,
bool force_nonblock)
{
@@ -2884,10 +2877,13 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)

static void __io_queue_sqe(struct io_kiocb *req)
{
- struct io_kiocb *nxt = io_prep_linked_timeout(req);
+ struct io_kiocb *linked_timeout = io_prep_linked_timeout(req);
+ struct io_kiocb *nxt = NULL;
int ret;

- ret = io_issue_sqe(req, NULL, true);
+ ret = io_issue_sqe(req, &nxt, true);
+ if (nxt)
+ io_queue_async_work(nxt);

/*
* We async punt it if the file wasn't marked NOWAIT, or if the file
@@ -2923,11 +2919,11 @@ static void __io_queue_sqe(struct io_kiocb *req)
/* drop submission reference */
io_put_req(req);

- if (nxt) {
+ if (linked_timeout) {
if (!ret)
- io_queue_linked_timeout(nxt);
+ io_queue_linked_timeout(linked_timeout);
else
- io_put_req(nxt);
+ io_put_req(linked_timeout);
}

/* and drop final reference, if we failed */
--
2.24.0