9p: add more conservative locking

During the reorganization some of the multi-theaded locking assumptions were
accidently relaxed.  This patch moves us back towards a more conservative 
locking strategy.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 17 insertions, 7 deletions

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index e8ebe2cb7e8b..be65d8242fd2 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -188,8 +188,16 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
         LIST_HEAD(cancel_list);
 
         P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
-        m->err = err;
+
         spin_lock_irqsave(&m->client->lock, flags);
+
+        if (m->err) {
+                spin_unlock_irqrestore(&m->client->lock, flags);
+                return;
+        }
+
+        m->err = err;
+
         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
                 req->status = REQ_STATUS_ERROR;
                 if (!req->t_err)
@@ -352,8 +360,9 @@ static void p9_read_work(struct work_struct *work)
         /* not an else because some packets (like clunk) have no payload */
         if ((m->req) && (m->rpos == m->rsize)) { /* packet is read in */
                 P9_DPRINTK(P9_DEBUG_TRANS, "got new packet\n");
-
+                spin_lock(&m->client->lock);
                 list_del(&m->req->req_list);
+                spin_unlock(&m->client->lock);
                 p9_client_cb(m->client, m->req);
 
                 m->rbuf = NULL;
@@ -651,9 +660,8 @@ static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
         if (m->err < 0)
                 return m->err;
 
-        req->status = REQ_STATUS_UNSENT;
-
         spin_lock(&client->lock);
+        req->status = REQ_STATUS_UNSENT;
         list_add_tail(&req->req_list, &m->unsent_req_list);
         spin_unlock(&client->lock);
 
@@ -672,19 +680,21 @@ static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)
 {
         struct p9_trans_fd *ts = client->trans;
         struct p9_conn *m = ts->conn;
+        int ret = 1;
 
         P9_DPRINTK(P9_DEBUG_TRANS, "mux %p req %p\n", m, req);
 
         spin_lock(&client->lock);
         list_del(&req->req_list);
-        spin_unlock(&client->lock);
 
         if (req->status == REQ_STATUS_UNSENT) {
                 req->status = REQ_STATUS_FLSHD;
-                return 0;
+                ret = 0;
         }
 
-        return 1;
+        spin_unlock(&client->lock);
+
+        return ret;
 }
 
 /**