io_uring: remove sqo_task

Now, sqo_task is used only for a warning that is not interesting anymore
since sqo_dead is gone, remove all of that including ctx->sqo_task.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -379,11 +379,6 @@ struct io_ring_ctx {
 
 	struct io_rings	*rings;
 
-	/*
-	 * For SQPOLL usage
-	 */
-	struct task_struct	*sqo_task;
-
 	/* Only used for accounting purposes */
 	struct mm_struct	*mm_account;
 
@@ -8747,10 +8742,6 @@ static int io_uring_add_task_file(struct io_ring_ctx *ctx, struct file *file)
 				fput(file);
 				return ret;
 			}
-
-			/* one and only SQPOLL file note, held by sqo_task */
-			WARN_ON_ONCE((ctx->flags & IORING_SETUP_SQPOLL) &&
-				     current != ctx->sqo_task);
 		}
 		tctx->last = file;
 	}
@@ -9376,7 +9367,6 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p,
 	ctx->compat = in_compat_syscall();
 	if (!capable(CAP_IPC_LOCK))
 		ctx->user = get_uid(current_user());
-	ctx->sqo_task = current;
 
 	/*
 	 * This is just grabbed for accounting purposes. When a process exits,