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Commit 1cff3306 authored by Simon Derr's avatar Simon Derr Committed by Eric Van Hensbergen
Browse files

9P/RDMA: count posted buffers without a pending request 



In rdma_request():

If an error occurs between posting the recv and the send,
there will be a reply context posted without a pending
request.
Since there is no way to "un-post" it, we remember it and
skip post_recv() for the next request.

Signed-off-by: default avatarSimon Derr <simon.derr@bull.net>
Signed-off-by: default avatarEric Van Hensbergen <ericvh@gmail.com>
parent 2f52d07c

net/9p/client.c

+4 −2
Original line number Diff line number Diff line
@@ -656,8 +656,10 @@ static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq) 
		return PTR_ERR(req);





	/* if we haven't received a response for oldreq,

	   remove it from the list. */

	/*

	 * if we haven't received a response for oldreq,

	 * remove it from the list.

	 */

	spin_lock(&c->lock);

	if (oldreq->status == REQ_STATUS_FLSH)

		list_del(&oldreq->req_list);

net/9p/trans_rdma.c

+30 −1
Original line number Diff line number Diff line
@@ -74,6 +74,8 @@ 
 * @sq_sem: Semaphore for the SQ

 * @rq_depth: The depth of the Receive Queue.

 * @rq_sem: Semaphore for the RQ

 * @excess_rc : Amount of posted Receive Contexts without a pending request.

 *		See rdma_request()

 * @addr: The remote peer's address

 * @req_lock: Protects the active request list

 * @cm_done: Completion event for connection management tracking
@@ -99,6 +101,7 @@ struct p9_trans_rdma { 
	struct semaphore sq_sem;

	int rq_depth;

	struct semaphore rq_sem;

	atomic_t excess_rc;

	struct sockaddr_in addr;

	spinlock_t req_lock;
@@ -426,6 +429,26 @@ static int rdma_request(struct p9_client *client, struct p9_req_t *req) 
	struct p9_rdma_context *c = NULL;

	struct p9_rdma_context *rpl_context = NULL;



	/* When an error occurs between posting the recv and the send,

	 * there will be a receive context posted without a pending request.

	 * Since there is no way to "un-post" it, we remember it and skip

	 * post_recv() for the next request.

	 * So here,

	 * see if we are this `next request' and need to absorb an excess rc.

	 * If yes, then drop and free our own, and do not recv_post().

	 **/

	if (unlikely(atomic_read(&rdma->excess_rc) > 0)) {

		if ((atomic_sub_return(1, &rdma->excess_rc) >= 0)) {

			/* Got one ! */

			kfree(req->rc);

			req->rc = NULL;

			goto dont_need_post_recv;

		} else {

			/* We raced and lost. */

			atomic_inc(&rdma->excess_rc);

		}

	}



	/* Allocate an fcall for the reply */

	rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS);

	if (!rpl_context) {
@@ -451,10 +474,10 @@ static int rdma_request(struct p9_client *client, struct p9_req_t *req) 
		p9_debug(P9_DEBUG_FCALL, "POST RECV failed\n");

		goto recv_error;

	}



	/* remove posted receive buffer from request structure */

	req->rc = NULL;



dont_need_post_recv:

	/* Post the request */

	c = kmalloc(sizeof *c, GFP_NOFS);

	if (!c) {
@@ -499,6 +522,11 @@ static int rdma_request(struct p9_client *client, struct p9_req_t *req) 
 send_error:

	kfree(c);

	p9_debug(P9_DEBUG_ERROR, "Error %d in rdma_request()\n", err);



	/* Ach.

	 *  We did recv_post(), but not send. We have one recv_post in excess.

	 */

	atomic_inc(&rdma->excess_rc);

	return err;



 /* Handle errors that happened during or while preparing post_recv(): */
@@ -549,6 +577,7 @@ static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts) 
	init_completion(&rdma->cm_done);

	sema_init(&rdma->sq_sem, rdma->sq_depth);

	sema_init(&rdma->rq_sem, rdma->rq_depth);

	atomic_set(&rdma->excess_rc, 0);



	return rdma;

}