Commit 83f84356 authored by Hao Xu's avatar Hao Xu Committed by Jens Axboe
Browse files

io_uring: add more uring info to fdinfo for debug 



Developers may need some uring info to help themselves debug and address
issues in production. This includes sqring/cqring head/tail and the
detailed sqe/cqe info, which is very useful when an application is hung
on a ring.

Signed-off-by: default avatarHao Xu <haoxu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20210913130854.38542-1-haoxu@linux.alibaba.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d97ec623

fs/io_uring.c

+55 −4
Original line number Diff line number Diff line
@@ -10056,8 +10056,48 @@ static int io_uring_show_cred(struct seq_file *m, unsigned int id, 
static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)

{

	struct io_sq_data *sq = NULL;

	struct io_overflow_cqe *ocqe;

	struct io_rings *r = ctx->rings;

	unsigned int sq_mask = ctx->sq_entries - 1, cq_mask = ctx->cq_entries - 1;

	unsigned int cached_sq_head = ctx->cached_sq_head;

	unsigned int cached_cq_tail = ctx->cached_cq_tail;

	unsigned int sq_head = READ_ONCE(r->sq.head);

	unsigned int sq_tail = READ_ONCE(r->sq.tail);

	unsigned int cq_head = READ_ONCE(r->cq.head);

	unsigned int cq_tail = READ_ONCE(r->cq.tail);

	bool has_lock;

	int i;

	unsigned int i;



	/*

	 * we may get imprecise sqe and cqe info if uring is actively running

	 * since we get cached_sq_head and cached_cq_tail without uring_lock

	 * and sq_tail and cq_head are changed by userspace. But it's ok since

	 * we usually use these info when it is stuck.

	 */

	seq_printf(m, "SqHead:\t%u\n", sq_head & sq_mask);

	seq_printf(m, "SqTail:\t%u\n", sq_tail & sq_mask);

	seq_printf(m, "CachedSqHead:\t%u\n", cached_sq_head & sq_mask);

	seq_printf(m, "CqHead:\t%u\n", cq_head & cq_mask);

	seq_printf(m, "CqTail:\t%u\n", cq_tail & cq_mask);

	seq_printf(m, "CachedCqTail:\t%u\n", cached_cq_tail & cq_mask);

	seq_printf(m, "SQEs:\t%u\n", sq_tail - cached_sq_head);

	for (i = cached_sq_head; i < sq_tail; i++) {

		unsigned int sq_idx = READ_ONCE(ctx->sq_array[i & sq_mask]);



		if (likely(sq_idx <= sq_mask)) {

			struct io_uring_sqe *sqe = &ctx->sq_sqes[sq_idx];



			seq_printf(m, "%5u: opcode:%d, fd:%d, flags:%x, user_data:%llu\n",

				   sq_idx, sqe->opcode, sqe->fd, sqe->flags, sqe->user_data);

		}

	}

	seq_printf(m, "CQEs:\t%u\n", cached_cq_tail - cq_head);

	for (i = cq_head; i < cached_cq_tail; i++) {

		struct io_uring_cqe *cqe = &r->cqes[i & cq_mask];



		seq_printf(m, "%5u: user_data:%llu, res:%d, flag:%x\n",

			   i & cq_mask, cqe->user_data, cqe->res, cqe->flags);

	}



	/*

	 * Avoid ABBA deadlock between the seq lock and the io_uring mutex,
@@ -10099,7 +10139,10 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) 
		xa_for_each(&ctx->personalities, index, cred)

			io_uring_show_cred(m, index, cred);

	}

	seq_printf(m, "PollList:\n");

	if (has_lock)

		mutex_unlock(&ctx->uring_lock);



	seq_puts(m, "PollList:\n");

	spin_lock(&ctx->completion_lock);

	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {

		struct hlist_head *list = &ctx->cancel_hash[i];
@@ -10109,9 +10152,17 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m) 
			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,

					req->task->task_works != NULL);

	}



	seq_puts(m, "CqOverflowList:\n");

	list_for_each_entry(ocqe, &ctx->cq_overflow_list, list) {

		struct io_uring_cqe *cqe = &ocqe->cqe;



		seq_printf(m, "  user_data=%llu, res=%d, flags=%x\n",

			   cqe->user_data, cqe->res, cqe->flags);



	}



	spin_unlock(&ctx->completion_lock);

	if (has_lock)

		mutex_unlock(&ctx->uring_lock);

}



static void io_uring_show_fdinfo(struct seq_file *m, struct file *f)