[PATCH 7/9] io_uring: don't fail overflow on in_idle

Pavel Begunkov
2021-04-13T02:03:11Z

As CQE overflows are now untied from requests and so don't hold any
ref, we don't need to handle exiting/exec'ing cases there anymore.
Moreover, it's much nicer in regards to userspace to save overflowed
CQEs whenever possible, so remove failing on in_idle.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
fs/io_uring.c | 44 ++++++++++++++++++++------------------------
1 file changed, 20 insertions(+), 24 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 4407ebc8f8d3..cc6a44533802 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1515,32 +1515,28 @@ static bool io_cqring_event_overflow(struct io_kiocb *req, long res,
unsigned int cflags)
{
struct io_ring_ctx *ctx = req->ctx;
+ struct io_overflow_cqe *ocqe;

- if (!atomic_read(&req->task->io_uring->in_idle)) {
- struct io_overflow_cqe *ocqe;
-
- ocqe = kmalloc(sizeof(*ocqe), GFP_ATOMIC | __GFP_ACCOUNT);
- if (!ocqe)
- goto overflow;
- if (list_empty(&ctx->cq_overflow_list)) {
- set_bit(0, &ctx->sq_check_overflow);
- set_bit(0, &ctx->cq_check_overflow);
- ctx->rings->sq_flags |= IORING_SQ_CQ_OVERFLOW;
- }
- ocqe->cqe.user_data = req->user_data;
- ocqe->cqe.res = res;
- ocqe->cqe.flags = cflags;
- list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
- return true;
+ ocqe = kmalloc(sizeof(*ocqe), GFP_ATOMIC | __GFP_ACCOUNT);
+ if (!ocqe) {
+ /*
+ * If we're in ring overflow flush mode, or in task cancel mode,
+ * or cannot allocate an overflow entry, then we need to drop it
+ * on the floor.
+ */
+ WRITE_ONCE(ctx->rings->cq_overflow, ++ctx->cached_cq_overflow);
+ return false;
}
-overflow:
- /*
- * If we're in ring overflow flush mode, or in task cancel mode,
- * or cannot allocate an overflow entry, then we need to drop it
- * on the floor.
- */
- WRITE_ONCE(ctx->rings->cq_overflow, ++ctx->cached_cq_overflow);
- return false;
+ if (list_empty(&ctx->cq_overflow_list)) {
+ set_bit(0, &ctx->sq_check_overflow);
+ set_bit(0, &ctx->cq_check_overflow);
+ ctx->rings->sq_flags |= IORING_SQ_CQ_OVERFLOW;
+ }
+ ocqe->cqe.user_data = req->user_data;
+ ocqe->cqe.res = res;
+ ocqe->cqe.flags = cflags;
+ list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
+ return true;
}

static inline bool __io_cqring_fill_event(struct io_kiocb *req, long res,
--
2.24.0