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Commit 3d4cf35b authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

xprtrdma: Reply buffer exhaustion can be catastrophic 



Not having an rpcrdma_rep at call_allocate time can be a problem.
It means that send_request can't post a receive buffer to catch
the RPC's reply. Possible consequences are RPC timeouts or even
transport deadlock.

Instead of allowing an RPC to proceed if an rpcrdma_rep is
not available, return NULL to force call_allocate to wait and
try again.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Tested-by: default avatarSteve Wise <swise@opengridcomputing.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent b54054ca

net/sunrpc/xprtrdma/verbs.c

+5 −7
Original line number Diff line number Diff line
@@ -871,7 +871,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt) 
	}



	INIT_LIST_HEAD(&buf->rb_recv_bufs);

	for (i = 0; i < buf->rb_max_requests + 2; i++) {

	for (i = 0; i < buf->rb_max_requests; i++) {

		struct rpcrdma_rep *rep;



		rep = rpcrdma_create_rep(r_xprt);
@@ -989,8 +989,6 @@ rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw) 


/*

 * Get a set of request/reply buffers.

 *

 * Reply buffer (if available) is attached to send buffer upon return.

 */

struct rpcrdma_req *

rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
@@ -1009,13 +1007,13 @@ rpcrdma_buffer_get(struct rpcrdma_buffer *buffers) 


out_reqbuf:

	spin_unlock(&buffers->rb_lock);

	pr_warn("RPC:       %s: out of request buffers\n", __func__);

	pr_warn("rpcrdma: out of request buffers (%p)\n", buffers);

	return NULL;

out_repbuf:

	list_add(&req->rl_free, &buffers->rb_send_bufs);

	spin_unlock(&buffers->rb_lock);

	pr_warn("RPC:       %s: out of reply buffers\n", __func__);

	req->rl_reply = NULL;

	return req;

	pr_warn("rpcrdma: out of reply buffers (%p)\n", buffers);

	return NULL;

}



/*