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xprtrdma: Fix backchannel allocation of extra rpcrdma_reps

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The backchannel code uses rpcrdma_recv_buffer_put to add new reps
to the free rep list. This also decrements rb_recv_count, which
spoofs the receive overrun logic in rpcrdma_buffer_get_rep.

Commit 9b06688bc3b9 ("xprtrdma: Fix additional uses of
spin_lock_irqsave(rb_lock)") replaced the original open-coded
list_add with a call to rpcrdma_recv_buffer_put(), but then a year
later, commit 05c974669ece ("xprtrdma: Fix receive buffer
accounting") added rep accounting to rpcrdma_recv_buffer_put.
It was an oversight to let the backchannel continue to use this
function.

The fix this, let's combine the "add to free list" logic with
rpcrdma_create_rep.

Also, do not allocate RPCRDMA_MAX_BC_REQUESTS rpcrdma_reps in
rpcrdma_buffer_create and then allocate additional rpcrdma_reps in
rpcrdma_bc_setup_reps. Allocating the extra reps during backchannel
set-up is sufficient.

Fixes: 05c974669ece ("xprtrdma: Fix receive buffer accounting")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2017-12-14 20:56:09 -05:00 committed by Anna Schumaker
parent 03ac1a76ce
commit d698c4a02e
3 changed files with 22 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/sunrpc/xprtrdma/backchannel.c
View File

@ -74,21 +74,13 @@ out_fail:
static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt,
unsigned int count)
{
struct rpcrdma_rep *rep;
int rc = 0;
while (count--) {
rep = rpcrdma_create_rep(r_xprt);
if (IS_ERR(rep)) {
pr_err("RPC: %s: reply buffer alloc failed\n",
__func__);
rc = PTR_ERR(rep);
rc = rpcrdma_create_rep(r_xprt);
if (rc)
break;
}
rpcrdma_recv_buffer_put(rep);
}
return rc;
}

32
net/sunrpc/xprtrdma/verbs.c
View File

@ -1093,10 +1093,17 @@ rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
return req;
}
struct rpcrdma_rep *
/**
* rpcrdma_create_rep - Allocate an rpcrdma_rep object
* @r_xprt: controlling transport
*
* Returns 0 on success or a negative errno on failure.
*/
int
rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
{
struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
struct rpcrdma_rep *rep;
int rc;
@ -1121,12 +1128,18 @@ rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
rep->rr_recv_wr.wr_cqe = &rep->rr_cqe;
rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
rep->rr_recv_wr.num_sge = 1;
return rep;
spin_lock(&buf->rb_lock);
list_add(&rep->rr_list, &buf->rb_recv_bufs);
spin_unlock(&buf->rb_lock);
return 0;
out_free:
kfree(rep);
out:
return ERR_PTR(rc);
dprintk("RPC: %s: reply buffer %d alloc failed\n",
__func__, rc);
return rc;
}
int
@ -1167,17 +1180,10 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
}
INIT_LIST_HEAD(&buf->rb_recv_bufs);
for (i = 0; i < buf->rb_max_requests + RPCRDMA_MAX_BC_REQUESTS; i++) {
struct rpcrdma_rep *rep;
rep = rpcrdma_create_rep(r_xprt);
if (IS_ERR(rep)) {
dprintk("RPC: %s: reply buffer %d alloc failed\n",
__func__, i);
rc = PTR_ERR(rep);
for (i = 0; i <= buf->rb_max_requests; i++) {
rc = rpcrdma_create_rep(r_xprt);
if (rc)
goto out;
}
list_add(&rep->rr_list, &buf->rb_recv_bufs);
}
rc = rpcrdma_sendctxs_create(r_xprt);

2
net/sunrpc/xprtrdma/xprt_rdma.h
View File

@ -564,8 +564,8 @@ int rpcrdma_ep_post_recv(struct rpcrdma_ia *, struct rpcrdma_rep *);
* Buffer calls - xprtrdma/verbs.c
*/
struct rpcrdma_req *rpcrdma_create_req(struct rpcrdma_xprt *);
struct rpcrdma_rep *rpcrdma_create_rep(struct rpcrdma_xprt *);
void rpcrdma_destroy_req(struct rpcrdma_req *);
int rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt);
int rpcrdma_buffer_create(struct rpcrdma_xprt *);
void rpcrdma_buffer_destroy(struct rpcrdma_buffer *);
struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_buffer *buf);