[PATCH 5.4 070/203] xprtrdma: Fix MR list handling

Greg Kroah-Hartman
2020-01-16T23:45:59Z

From: Chuck Lever <chuck.lever@oracle.com>

commit c3700780a096fc66467c81076ddf7f3f11d639b5 upstream.

Close some holes introduced by commit 6dc6ec9e04c4 ("xprtrdma: Cache
free MRs in each rpcrdma_req") that could result in list corruption.

In addition, the result that is tabulated in @count is no longer
used, so @count is removed.

Fixes: 6dc6ec9e04c4 ("xprtrdma: Cache free MRs in each rpcrdma_req")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sunrpc/xprtrdma/verbs.c | 41 +++++++++++++++++++++--------------------
1 file changed, 21 insertions(+), 20 deletions(-)

--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -79,7 +79,6 @@ static void rpcrdma_reqs_reset(struct rp
static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf);
static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
static void rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf);
-static void rpcrdma_mr_free(struct rpcrdma_mr *mr);
static struct rpcrdma_regbuf *
rpcrdma_regbuf_alloc(size_t size, enum dma_data_direction direction,
gfp_t flags);
@@ -967,7 +966,7 @@ rpcrdma_mrs_create(struct rpcrdma_xprt *
mr->mr_xprt = r_xprt;

spin_lock(&buf->rb_lock);
- list_add(&mr->mr_list, &buf->rb_mrs);
+ rpcrdma_mr_push(mr, &buf->rb_mrs);
list_add(&mr->mr_all, &buf->rb_all_mrs);
spin_unlock(&buf->rb_lock);
}
@@ -1185,10 +1184,19 @@ out:
*/
void rpcrdma_req_destroy(struct rpcrdma_req *req)
{
+ struct rpcrdma_mr *mr;
+
list_del(&req->rl_all);

- while (!list_empty(&req->rl_free_mrs))
- rpcrdma_mr_free(rpcrdma_mr_pop(&req->rl_free_mrs));
+ while ((mr = rpcrdma_mr_pop(&req->rl_free_mrs))) {
+ struct rpcrdma_buffer *buf = &mr->mr_xprt->rx_buf;
+
+ spin_lock(&buf->rb_lock);
+ list_del(&mr->mr_all);
+ spin_unlock(&buf->rb_lock);
+
+ frwr_release_mr(mr);
+ }

rpcrdma_regbuf_free(req->rl_recvbuf);
rpcrdma_regbuf_free(req->rl_sendbuf);
@@ -1196,24 +1204,28 @@ void rpcrdma_req_destroy(struct rpcrdma_
kfree(req);
}

-static void
-rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf)
+/**
+ * rpcrdma_mrs_destroy - Release all of a transport's MRs
+ * @buf: controlling buffer instance
+ *
+ * Relies on caller holding the transport send lock to protect
+ * removing mr->mr_list from req->rl_free_mrs safely.
+ */
+static void rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf)
{
struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
rx_buf);
struct rpcrdma_mr *mr;
- unsigned int count;

- count = 0;
spin_lock(&buf->rb_lock);
while ((mr = list_first_entry_or_null(&buf->rb_all_mrs,
struct rpcrdma_mr,
mr_all)) != NULL) {
+ list_del(&mr->mr_list);
list_del(&mr->mr_all);
spin_unlock(&buf->rb_lock);

frwr_release_mr(mr);
- count++;
spin_lock(&buf->rb_lock);
}
spin_unlock(&buf->rb_lock);
@@ -1286,17 +1298,6 @@ void rpcrdma_mr_put(struct rpcrdma_mr *m
rpcrdma_mr_push(mr, &mr->mr_req->rl_free_mrs);
}

-static void rpcrdma_mr_free(struct rpcrdma_mr *mr)
-{
- struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
- struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
-
- mr->mr_req = NULL;
- spin_lock(&buf->rb_lock);
- rpcrdma_mr_push(mr, &buf->rb_mrs);
- spin_unlock(&buf->rb_lock);
-}
-
/**
* rpcrdma_buffer_get - Get a request buffer
* @buffers: Buffer pool from which to obtain a buffer