[PATCH v4 02/21] xprtrdma: Protect ia->ri_id when unmapping/invalidating MRs

Chuck Lever
2014-07-22T14:51:16Z

Ensure ia->ri_id remains valid while invoking dma_unmap_page() or
posting LOCAL_INV during a transport reconnect. Otherwise,
ia->ri_id->device or ia->ri_id->qp is NULL, which triggers a panic.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=259
Fixes: ec62f40 'xprtrdma: Ensure ia->ri_id->qp is not NULL when reconnecting'
Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
Tested-by: Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Devesh Sharma <devesh.sharma-laKkSmNT4hbQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/verbs.c | 23 +++++++++++++++++------
net/sunrpc/xprtrdma/xprt_rdma.h | 1 +
2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 78bd7c6..cab742d 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -613,6 +613,7 @@ rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
/* Else will do memory reg/dereg for each chunk */
ia->ri_memreg_strategy = memreg;

+ rwlock_init(&ia->ri_qplock);
return 0;
out2:
rdma_destroy_id(ia->ri_id);
@@ -859,7 +860,7 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
int
rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
- struct rdma_cm_id *id;
+ struct rdma_cm_id *id, *old;
int rc = 0;
int retry_count = 0;

@@ -905,9 +906,14 @@ retry:
rc = -ENETUNREACH;
goto out;
}
- rdma_destroy_qp(ia->ri_id);
- rdma_destroy_id(ia->ri_id);
+
+ write_lock(&ia->ri_qplock);
+ old = ia->ri_id;
ia->ri_id = id;
+ write_unlock(&ia->ri_qplock);
+
+ rdma_destroy_qp(old);
+ rdma_destroy_id(old);
} else {
dprintk("RPC: %s: connecting...\n", __func__);
rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
@@ -1587,9 +1593,6 @@ rpcrdma_deregister_frmr_external(struct rpcrdma_mr_seg *seg,
struct ib_send_wr invalidate_wr, *bad_wr;
int rc;

- while (seg1->mr_nsegs--)
- rpcrdma_unmap_one(ia, seg++);
-
memset(&invalidate_wr, 0, sizeof invalidate_wr);
invalidate_wr.wr_id = (unsigned long)(void *)seg1->mr_chunk.rl_mw;
invalidate_wr.opcode = IB_WR_LOCAL_INV;
@@ -1597,7 +1600,11 @@ rpcrdma_deregister_frmr_external(struct rpcrdma_mr_seg *seg,
invalidate_wr.ex.invalidate_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
DECR_CQCOUNT(&r_xprt->rx_ep);

+ read_lock(&ia->ri_qplock);
+ while (seg1->mr_nsegs--)
+ rpcrdma_unmap_one(ia, seg++);
rc = ib_post_send(ia->ri_id->qp, &invalidate_wr, &bad_wr);
+ read_unlock(&ia->ri_qplock);
if (rc)
dprintk("RPC: %s: failed ib_post_send for invalidate,"
" status %i\n", __func__, rc);
@@ -1658,8 +1665,10 @@ rpcrdma_deregister_fmr_external(struct rpcrdma_mr_seg *seg,

list_add(&seg1->mr_chunk.rl_mw->r.fmr->list, &l);
rc = ib_unmap_fmr(&l);
+ read_lock(&ia->ri_qplock);
while (seg1->mr_nsegs--)
rpcrdma_unmap_one(ia, seg++);
+ read_unlock(&ia->ri_qplock);
if (rc)
dprintk("RPC: %s: failed ib_unmap_fmr,"
" status %i\n", __func__, rc);
@@ -1715,7 +1724,9 @@ rpcrdma_deregister_external(struct rpcrdma_mr_seg *seg,

#if RPCRDMA_PERSISTENT_REGISTRATION
case RPCRDMA_ALLPHYSICAL:
+ read_lock(&ia->ri_qplock);
rpcrdma_unmap_one(ia, seg);
+ read_unlock(&ia->ri_qplock);
break;
#endif

diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 89e7cd4..97ca516 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -59,6 +59,7 @@
* Interface Adapter -- one per transport instance
*/
struct rpcrdma_ia {
+ rwlock_t ri_qplock;
struct rdma_cm_id *ri_id;
struct ib_pd *ri_pd;
struct ib_mr *ri_bind_mem;