9p: eliminate callback complexity

The current trans_fd rpc mechanisms use a dynamic callback mechanism which
introduces a lot of complexity which only accomodates a single special case.
This patch removes much of that complexity in favor of a simple exception
mechanism to deal with flushes.

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

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index dbb057d..180163b 100644 (file)
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -105,9 +105,6 @@ enum {
        Flushed,
 };
 
-struct p9_req;
-typedef void (*p9_conn_req_callback)(struct p9_req *req, void *a);
-
 /**
  * struct p9_req - fd mux encoding of an rpc transaction
  * @lock: protects req_list
@@ -115,8 +112,6 @@ typedef void (*p9_conn_req_callback)(struct p9_req *req, void *a);
  * @tcall: request &p9_fcall structure
  * @rcall: response &p9_fcall structure
  * @err: error state
- * @cb: callback for when response is received
- * @cba: argument to pass to callback
  * @flush: flag to indicate RPC has been flushed
  * @req_list: list link for higher level objects to chain requests
  * @m: connection this request was issued on
@@ -130,8 +125,6 @@ struct p9_req {
        struct p9_fcall *tcall;
        struct p9_fcall *rcall;
        int err;
-       p9_conn_req_callback cb;
-       void *cba;
        int flush;
        struct list_head req_list;
        struct p9_conn *m;
@@ -231,6 +224,65 @@ static void p9_mux_poll_stop(struct p9_conn *m)
        spin_unlock_irqrestore(&p9_poll_lock, flags);
 }
 
+static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
+{
+       p9_mux_put_tag(m, req->tag);
+       kfree(req);
+}
+
+static void p9_conn_rpc_cb(struct p9_req *req);
+
+static void p9_mux_flush_cb(struct p9_req *freq)
+{
+       int tag;
+       struct p9_conn *m = freq->m;
+       struct p9_req *req, *rreq, *rptr;
+
+       P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
+               freq->tcall, freq->rcall, freq->err,
+               freq->tcall->params.tflush.oldtag);
+
+       spin_lock(&m->lock);
+       tag = freq->tcall->params.tflush.oldtag;
+       req = NULL;
+       list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
+               if (rreq->tag == tag) {
+                       req = rreq;
+                       list_del(&req->req_list);
+                       break;
+               }
+       }
+       spin_unlock(&m->lock);
+
+       if (req) {
+               spin_lock(&req->lock);
+               req->flush = Flushed;
+               spin_unlock(&req->lock);
+
+               p9_conn_rpc_cb(req);
+       }
+
+       kfree(freq->tcall);
+       kfree(freq->rcall);
+       p9_mux_free_request(m, freq);
+}
+
+static void p9_conn_rpc_cb(struct p9_req *req)
+{
+       P9_DPRINTK(P9_DEBUG_MUX, "req %p\n", req);
+
+       if (req->tcall->id == P9_TFLUSH) { /* flush callback */
+               P9_DPRINTK(P9_DEBUG_MUX, "flush req %p\n", req);
+               p9_mux_flush_cb(req);
+       } else {                        /* normal wakeup path */
+               P9_DPRINTK(P9_DEBUG_MUX, "normal req %p\n", req);
+               if (req->flush != None && !req->err)
+                       req->err = -ERESTARTSYS;
+
+               wake_up(&req->wqueue);
+       }
+}
+
 /**
  * p9_conn_cancel - cancel all pending requests with error
  * @m: mux data
@@ -259,10 +311,7 @@ void p9_conn_cancel(struct p9_conn *m, int err)
                if (!req->err)
                        req->err = err;
 
-               if (req->cb)
-                       (*req->cb) (req, req->cba);
-               else
-                       kfree(req->rcall);
+               p9_conn_rpc_cb(req);
        }
 }
 
@@ -472,12 +521,8 @@ static void p9_read_work(struct work_struct *work)
                        req->rcall = rcall;
                        process_request(m, req);
 
-                       if (req->flush != Flushing) {
-                               if (req->cb)
-                                       (*req->cb) (req, req->cba);
-                               else
-                                       kfree(req->rcall);
-                       }
+                       if (req->flush != Flushing)
+                               p9_conn_rpc_cb(req);
                } else {
                        if (err >= 0 && rcall->id != P9_RFLUSH)
                                P9_DPRINTK(P9_DEBUG_ERROR,
@@ -786,14 +831,10 @@ static void p9_poll_mux(struct p9_conn *m)
  *
  * @m: mux data
  * @tc: request to be sent
- * @cb: callback function to call when response is received
- * @cba: parameter to pass to the callback function
  *
  */
 
-static struct p9_req *p9_send_request(struct p9_conn *m,
-                                         struct p9_fcall *tc,
-                                         p9_conn_req_callback cb, void *cba)
+static struct p9_req *p9_send_request(struct p9_conn *m, struct p9_fcall *tc)
 {
        int n;
        struct p9_req *req;
@@ -835,8 +876,6 @@ static struct p9_req *p9_send_request(struct p9_conn *m,
        req->tcall = tc;
        req->rcall = NULL;
        req->err = 0;
-       req->cb = cb;
-       req->cba = cba;
        req->flush = None;
 
        spin_lock(&m->lock);
@@ -854,51 +893,6 @@ static struct p9_req *p9_send_request(struct p9_conn *m,
        return req;
 }
 
-static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
-{
-       p9_mux_put_tag(m, req->tag);
-       kfree(req);
-}
-
-static void p9_mux_flush_cb(struct p9_req *freq, void *a)
-{
-       int tag;
-       struct p9_conn *m;
-       struct p9_req *req, *rreq, *rptr;
-
-       m = a;
-       P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
-               freq->tcall, freq->rcall, freq->err,
-               freq->tcall->params.tflush.oldtag);
-
-       spin_lock(&m->lock);
-       tag = freq->tcall->params.tflush.oldtag;
-       req = NULL;
-       list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
-               if (rreq->tag == tag) {
-                       req = rreq;
-                       list_del(&req->req_list);
-                       break;
-               }
-       }
-       spin_unlock(&m->lock);
-
-       if (req) {
-               spin_lock(&req->lock);
-               req->flush = Flushed;
-               spin_unlock(&req->lock);
-
-               if (req->cb)
-                       (*req->cb) (req, req->cba);
-               else
-                       kfree(req->rcall);
-       }
-
-       kfree(freq->tcall);
-       kfree(freq->rcall);
-       p9_mux_free_request(m, freq);
-}
-
 static int
 p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
 {
@@ -928,8 +922,7 @@ p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
                        list_del(&rreq->req_list);
                        req->flush = Flushed;
                        spin_unlock(&m->lock);
-                       if (req->cb)
-                               (*req->cb) (req, req->cba);
+                       p9_conn_rpc_cb(req);
                        return 0;
                }
        }
@@ -937,20 +930,10 @@ p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
 
        clear_thread_flag(TIF_SIGPENDING);
        fc = p9_create_tflush(req->tag);
-       p9_send_request(m, fc, p9_mux_flush_cb, m);
+       p9_send_request(m, fc);
        return 1;
 }
 
-static void p9_conn_rpc_cb(struct p9_req *req, void *a)
-{
-       P9_DPRINTK(P9_DEBUG_MUX, "req %p arg %p\n", req, a);
-
-       if (req->flush != None && !req->err)
-               req->err = -ERESTARTSYS;
-
-       wake_up(&req->wqueue);
-}
-
 /**
  * p9_fd_rpc- sends 9P request and waits until a response is available.
  *     The function can be interrupted.
@@ -978,7 +961,7 @@ p9_fd_rpc(struct p9_client *client, struct p9_fcall *tc, struct p9_fcall **rc)
                clear_thread_flag(TIF_SIGPENDING);
        }
 
-       req = p9_send_request(m, tc, p9_conn_rpc_cb, NULL);
+       req = p9_send_request(m, tc);
        if (IS_ERR(req)) {
                err = PTR_ERR(req);
                P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);