There are rare cases where an rpcrdma_req can be re-used (via
rpcrdma_buffer_put) while the RPC reply handler is still running.
This is due to a signal firing at just the wrong instant.
Since commit 9d6b04097882 ("xprtrdma: Place registered MWs on a
per-req list"), rpcrdma_mws are self-contained; ie., they fully
describe an MR and scatterlist, and no part of that information is
stored in struct rpcrdma_req.
As part of closing the above race window, pass only the req's list
of registered MRs to ro_unmap_sync, rather than the rpcrdma_req
itself.
Some extra transport header sanity checking is removed. Since the
client depends on its own recollection of what memory had been
registered, there doesn't seem to be a way to abuse this change.
And, the check was not terribly effective. If the client had sent
Read chunks, the "list_empty" test is negative in both of the
removed cases, which are actually looking for Write or Reply
chunks.
BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=305
Fixes: 68791649a725 ('xprtrdma: Invalidate in the RPC reply ... ')
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
net/sunrpc/xprtrdma/fmr_ops.c | 16 +++++++++-------
net/sunrpc/xprtrdma/frwr_ops.c | 17 ++++++++---------
net/sunrpc/xprtrdma/rpc_rdma.c | 16 +++++++---------
net/sunrpc/xprtrdma/xprt_rdma.h | 2 +-
4 files changed, 25 insertions(+), 26 deletions(-)
diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
index 7b2de86..2f4eacd 100644
--- a/net/sunrpc/xprtrdma/fmr_ops.c
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -255,24 +255,26 @@ enum {
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
- * Caller ensures that req->rl_registered is not empty.
+ * Caller ensures that @mws is not empty before the call. This
+ * function empties the list.
*/
static void
-fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
+fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mws)
{
struct rpcrdma_mw *mw, *tmp;
LIST_HEAD(unmap_list);
int rc;
- dprintk("RPC: %s: req %p\n", __func__, req);
-
/* ORDER: Invalidate all of the req's MRs first
*
* ib_unmap_fmr() is slow, so use a single call instead
* of one call per mapped FMR.
*/
- list_for_each_entry(mw, &req->rl_registered, mw_list)
+ list_for_each_entry(mw, mws, mw_list) {
+ dprintk("RPC: %s: unmapping fmr %p\n",
+ __func__, &mw->fmr);
list_add_tail(&mw->fmr.fm_mr->list, &unmap_list);
+ }
r_xprt->rx_stats.local_inv_needed++;
rc = ib_unmap_fmr(&unmap_list);
if (rc)
@@ -281,7 +283,7 @@ enum {
/* ORDER: Now DMA unmap all of the req's MRs, and return
* them to the free MW list.
*/
- list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
+ list_for_each_entry_safe(mw, tmp, mws, mw_list) {
list_del_init(&mw->mw_list);
list_del_init(&mw->fmr.fm_mr->list);
ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
@@ -294,7 +296,7 @@ enum {
out_reset:
pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
- list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
+ list_for_each_entry_safe(mw, tmp, mws, mw_list) {
list_del_init(&mw->mw_list);
list_del_init(&mw->fmr.fm_mr->list);
fmr_op_recover_mr(mw);
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index 9c0fa4a..8f63d38 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -455,10 +455,11 @@
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
- * Caller ensures that req->rl_registered is not empty.
+ * Caller ensures that @mws is not empty before the call. This
+ * function empties the list.
*/
static void
-frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
+frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mws)
{
struct ib_send_wr *first, **prev, *last, *bad_wr;
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
@@ -466,9 +467,7 @@
struct rpcrdma_mw *mw;
int count, rc;
- dprintk("RPC: %s: req %p\n", __func__, req);
-
- /* ORDER: Invalidate all of the req's MRs first
+ /* ORDER: Invalidate all of the MRs first
*
* Chain the LOCAL_INV Work Requests and post them with
* a single ib_post_send() call.
@@ -476,7 +475,7 @@
f = NULL;
count = 0;
prev = &first;
- list_for_each_entry(mw, &req->rl_registered, mw_list) {
+ list_for_each_entry(mw, mws, mw_list) {
mw->frmr.fr_state = FRMR_IS_INVALID;
if (mw->mw_flags & RPCRDMA_MW_F_RI)
@@ -526,12 +525,12 @@
if (rc)
goto reset_mrs;
- /* ORDER: Now DMA unmap all of the req's MRs, and return
+ /* ORDER: Now DMA unmap all of the MRs, and return
* them to the free MW list.
*/
unmap:
- while (!list_empty(&req->rl_registered)) {
- mw = rpcrdma_pop_mw(&req->rl_registered);
+ while (!list_empty(mws)) {
+ mw = rpcrdma_pop_mw(mws);
dprintk("RPC: %s: DMA unmapping frmr %p\n",
__func__, &mw->frmr);
ib_dma_unmap_sg(ia->ri_device,
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 2356a63..c88132d 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -995,6 +995,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
__be32 *iptr;
int rdmalen, status, rmerr;
unsigned long cwnd;
+ struct list_head mws;
dprintk("RPC: %s: incoming rep %p\n", __func__, rep);
@@ -1024,7 +1025,8 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
/* Sanity checking has passed. We are now committed
* to complete this transaction.
*/
- rpcrdma_mark_remote_invalidation(&req->rl_registered, rep);
+ list_replace_init(&req->rl_registered, &mws);
+ rpcrdma_mark_remote_invalidation(&mws, rep);
list_del_init(&rqst->rq_list);
req->rl_reply = rep;
spin_unlock_bh(&xprt->transport_lock);
@@ -1042,12 +1044,9 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
case rdma_msg:
/* never expect read chunks */
/* never expect reply chunks (two ways to check) */
- /* never expect write chunks without having offered RDMA */
if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
(headerp->rm_body.rm_chunks[1] == xdr_zero &&
- headerp->rm_body.rm_chunks[2] != xdr_zero) ||
- (headerp->rm_body.rm_chunks[1] != xdr_zero &&
- list_empty(&req->rl_registered)))
+ headerp->rm_body.rm_chunks[2] != xdr_zero))
goto badheader;
if (headerp->rm_body.rm_chunks[1] != xdr_zero) {
/* count any expected write chunks in read reply */
@@ -1084,8 +1083,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
/* never expect read or write chunks, always reply chunks */
if (headerp->rm_body.rm_chunks[0] != xdr_zero ||
headerp->rm_body.rm_chunks[1] != xdr_zero ||
- headerp->rm_body.rm_chunks[2] != xdr_one ||
- list_empty(&req->rl_registered))
+ headerp->rm_body.rm_chunks[2] != xdr_one)
goto badheader;
iptr = (__be32 *)((unsigned char *)headerp +
RPCRDMA_HDRLEN_MIN);
@@ -1118,8 +1116,8 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
* control: waking the next RPC waits until this RPC has
* relinquished all its Send Queue entries.
*/
- if (!list_empty(&req->rl_registered))
- r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, req);
+ if (!list_empty(&mws))
+ r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, &mws);
spin_lock_bh(&xprt->transport_lock);
cwnd = xprt->cwnd;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 2e02733..1c23117 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -467,7 +467,7 @@ struct rpcrdma_memreg_ops {
struct rpcrdma_mr_seg *, int, bool,
struct rpcrdma_mw **);
void (*ro_unmap_sync)(struct rpcrdma_xprt *,
- struct rpcrdma_req *);
+ struct list_head *);
void (*ro_unmap_safe)(struct rpcrdma_xprt *,
struct rpcrdma_req *, bool);
void (*ro_recover_mr)(struct rpcrdma_mw *);
--
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