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xprtrdma: Reply buffer exhaustion can be catastrophic

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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: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2016-06-29 13:53:35 -04:00 committed by Anna Schumaker
parent b54054ca55
commit 3d4cf35bd4
1 changed files with 5 additions and 7 deletions
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12
net/sunrpc/xprtrdma/verbs.c
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@ -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;
}
/*