io_uring: consolidate overflow flushing

Consolidate __io_cqring_overflow_flush and io_cqring_overflow_kill()
into a single function as it once was, it's easier to work with it this
way.

Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/986b42c35e76a6be7aa0cdcda0a236a2222da3a7.1712708261.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>

io_uring/io_uring.c

@@ -668,26 +668,7 @@ static void io_cq_unlock_post(struct io_ring_ctx *ctx)
  io_commit_cqring_flush(ctx);
 }
 
-static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
-{
- struct io_overflow_cqe *ocqe;
- LIST_HEAD(list);
-
- lockdep_assert_held(&ctx->uring_lock);
-
- spin_lock(&ctx->completion_lock);
- list_splice_init(&ctx->cq_overflow_list, &list);
- clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
- spin_unlock(&ctx->completion_lock);
-
- while (!list_empty(&list)) {
- ocqe = list_first_entry(&list, struct io_overflow_cqe, list);
- list_del(&ocqe->list);
- kfree(ocqe);
- }
-}
-
-static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
+static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool dying)
 {
  size_t cqe_size = sizeof(struct io_uring_cqe);
 
@@ -704,11 +685,14 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
  struct io_uring_cqe *cqe;
  struct io_overflow_cqe *ocqe;
 
- if (!io_get_cqe_overflow(ctx, &cqe, true))
- break;
  ocqe = list_first_entry(&ctx->cq_overflow_list,
  struct io_overflow_cqe, list);
- memcpy(cqe, &ocqe->cqe, cqe_size);
+
+ if (!dying) {
+ if (!io_get_cqe_overflow(ctx, &cqe, true))
+ break;
+ memcpy(cqe, &ocqe->cqe, cqe_size);
+ }
  list_del(&ocqe->list);
  kfree(ocqe);
  }
@@ -720,10 +704,16 @@ static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
  io_cq_unlock_post(ctx);
 }
 
+static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
+{
+ if (ctx->rings)
+ __io_cqring_overflow_flush(ctx, true);
+}
+
 static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx)
 {
  mutex_lock(&ctx->uring_lock);
- __io_cqring_overflow_flush(ctx);
+ __io_cqring_overflow_flush(ctx, false);
  mutex_unlock(&ctx->uring_lock);
 }
 
@@ -1531,7 +1521,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
  check_cq = READ_ONCE(ctx->check_cq);
  if (unlikely(check_cq)) {
  if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
- __io_cqring_overflow_flush(ctx);
+ __io_cqring_overflow_flush(ctx, false);
  /*
  * Similarly do not spin if we have not informed the user of any
  * dropped CQE.