Commit 2acc5cae authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

xprtrdma: Prevent dereferencing r_xprt->rx_ep after it is freed 



r_xprt->rx_ep is known to be good while the transport's send lock is
held.  Otherwise additional references on rx_ep must be held when it
is used outside of that lock's critical sections.

For now, bump the rx_ep reference count once whenever there is at
least one outstanding Receive WR. This avoids the memory bandwidth
overhead of taking and releasing the reference count for every
ib_post_recv() and Receive completion.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 48778464

net/sunrpc/xprtrdma/verbs.c

+23 −10
Original line number Diff line number Diff line
@@ -84,7 +84,8 @@ static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep); 
static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt);

static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);

static void rpcrdma_mrs_destroy(struct rpcrdma_xprt *r_xprt);

static int rpcrdma_ep_destroy(struct rpcrdma_ep *ep);

static void rpcrdma_ep_get(struct rpcrdma_ep *ep);

static int rpcrdma_ep_put(struct rpcrdma_ep *ep);

static struct rpcrdma_regbuf *

rpcrdma_regbuf_alloc(size_t size, enum dma_data_direction direction,

		     gfp_t flags);
@@ -97,7 +98,8 @@ static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb); 
 */

static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt)

{

	struct rdma_cm_id *id = r_xprt->rx_ep->re_id;

	struct rpcrdma_ep *ep = r_xprt->rx_ep;

	struct rdma_cm_id *id = ep->re_id;



	/* Flush Receives, then wait for deferred Reply work

	 * to complete.
@@ -108,6 +110,8 @@ static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt) 
	 * local invalidations.

	 */

	ib_drain_sq(id->qp);



	rpcrdma_ep_put(ep);

}



/**
@@ -266,7 +270,7 @@ rpcrdma_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event) 
		xprt_force_disconnect(xprt);

		goto disconnected;

	case RDMA_CM_EVENT_ESTABLISHED:

		kref_get(&ep->re_kref);

		rpcrdma_ep_get(ep);

		ep->re_connect_status = 1;

		rpcrdma_update_cm_private(ep, &event->param.conn);

		trace_xprtrdma_inline_thresh(ep);
@@ -289,7 +293,7 @@ rpcrdma_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event) 
		ep->re_connect_status = -ECONNABORTED;

disconnected:

		xprt_force_disconnect(xprt);

		return rpcrdma_ep_destroy(ep);

		return rpcrdma_ep_put(ep);

	default:

		break;

	}
@@ -345,7 +349,7 @@ out: 
	return ERR_PTR(rc);

}



static void rpcrdma_ep_put(struct kref *kref)

static void rpcrdma_ep_destroy(struct kref *kref)

{

	struct rpcrdma_ep *ep = container_of(kref, struct rpcrdma_ep, re_kref);
@@ -369,13 +373,18 @@ static void rpcrdma_ep_put(struct kref *kref) 
	module_put(THIS_MODULE);

}



static noinline void rpcrdma_ep_get(struct rpcrdma_ep *ep)

{

	kref_get(&ep->re_kref);

}



/* Returns:

 *     %0 if @ep still has a positive kref count, or

 *     %1 if @ep was destroyed successfully.

 */

static int rpcrdma_ep_destroy(struct rpcrdma_ep *ep)

static noinline int rpcrdma_ep_put(struct rpcrdma_ep *ep)

{

	return kref_put(&ep->re_kref, rpcrdma_ep_put);

	return kref_put(&ep->re_kref, rpcrdma_ep_destroy);

}



static int rpcrdma_ep_create(struct rpcrdma_xprt *r_xprt)
@@ -492,7 +501,7 @@ static int rpcrdma_ep_create(struct rpcrdma_xprt *r_xprt) 
	return 0;



out_destroy:

	rpcrdma_ep_destroy(ep);

	rpcrdma_ep_put(ep);

	rdma_destroy_id(id);

out_free:

	kfree(ep);
@@ -521,8 +530,12 @@ retry: 


	ep->re_connect_status = 0;

	xprt_clear_connected(xprt);



	rpcrdma_reset_cwnd(r_xprt);



	/* Bump the ep's reference count while there are

	 * outstanding Receives.

	 */

	rpcrdma_ep_get(ep);

	rpcrdma_post_recvs(r_xprt, true);



	rc = rpcrdma_sendctxs_create(r_xprt);
@@ -587,7 +600,7 @@ void rpcrdma_xprt_disconnect(struct rpcrdma_xprt *r_xprt) 
	rpcrdma_mrs_destroy(r_xprt);

	rpcrdma_sendctxs_destroy(r_xprt);



	if (rpcrdma_ep_destroy(ep))

	if (rpcrdma_ep_put(ep))

		rdma_destroy_id(id);



	r_xprt->rx_ep = NULL;

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