9p: use the rcall structure passed in the request in trans_fd read_work

This patch reworks the read_work function to enable it to directly use a passed
in rcall structure.  This should help allow us to remove unnecessary copies
in the future.

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

1 files changed, 66 insertions, 63 deletions

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index cc9bc739e9d3..627e3f097fc5 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -111,7 +111,9 @@ struct p9_poll_wait {
  * @err: error state
  * @req_list: accounting for requests which have been sent
  * @unsent_req_list: accounting for requests that haven't been sent
- * @rcall: current response &p9_fcall structure
+ * @req: current request being processed (if any)
+ * @tmp_buf: temporary buffer to read in header
+ * @rsize: amount to read for current frame
  * @rpos: read position in current frame
  * @rbuf: current read buffer
  * @wpos: write position for current frame
@@ -132,7 +134,9 @@ struct p9_conn {
         int err;
         struct list_head req_list;
         struct list_head unsent_req_list;
-        struct p9_fcall *rcall;
+        struct p9_req_t *req;
+        char tmp_buf[7];
+        int rsize;
         int rpos;
         char *rbuf;
         int wpos;
@@ -346,34 +350,25 @@ static void p9_read_work(struct work_struct *work)
 {
         int n, err;
         struct p9_conn *m;
-        struct p9_req_t *req;
-        struct p9_fcall *rcall;
-        char *rbuf;
 
         m = container_of(work, struct p9_conn, rq);
 
         if (m->err < 0)
                 return;
 
-        rcall = NULL;
         P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 
-        if (!m->rcall) {
-                m->rcall =
-                    kmalloc(sizeof(struct p9_fcall) + m->client->msize,
-                                                                GFP_KERNEL);
-                if (!m->rcall) {
-                        err = -ENOMEM;
-                        goto error;
-                }
-
-                m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
+        if (!m->rbuf) {
+                m->rbuf = m->tmp_buf;
                 m->rpos = 0;
+                m->rsize = 7; /* start by reading header */
         }
 
         clear_bit(Rpending, &m->wsched);
+        P9_DPRINTK(P9_DEBUG_MUX, "read mux %p pos %d size: %d = %d\n", m,
+                                        m->rpos, m->rsize, m->rsize-m->rpos);
         err = p9_fd_read(m->client, m->rbuf + m->rpos,
-                                                m->client->msize - m->rpos);
+                                                m->rsize - m->rpos);
         P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
         if (err == -EAGAIN) {
                 clear_bit(Rworksched, &m->wsched);
@@ -384,8 +379,12 @@ static void p9_read_work(struct work_struct *work)
                 goto error;
 
         m->rpos += err;
-        while (m->rpos > 4) {
-                n = le32_to_cpu(*(__le32 *) m->rbuf);
+
+        if ((!m->req) && (m->rpos == m->rsize)) { /* header read in */
+                u16 tag;
+                P9_DPRINTK(P9_DEBUG_MUX, "got new header\n");
+
+                n = le32_to_cpu(*(__le32 *) m->rbuf); /* read packet size */
                 if (n >= m->client->msize) {
                         P9_DPRINTK(P9_DEBUG_ERROR,
                                 "requested packet size too big: %d\n", n);
@@ -393,66 +392,71 @@ static void p9_read_work(struct work_struct *work)
                         goto error;
                 }
 
-                if (m->rpos < n)
-                        break;
+                tag = le16_to_cpu(*(__le16 *) (m->rbuf+5)); /* read tag */
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p pkt: size: %d bytes tag: %d\n",
+                                                                 m, n, tag);
 
-                err =
-                    p9_deserialize_fcall(m->rbuf, n, m->rcall, m->client->dotu);
-                if (err < 0)
+                m->req = p9_tag_lookup(m->client, tag);
+                if (!m->req) {
+                        P9_DPRINTK(P9_DEBUG_ERROR, "Unexpected packet tag %d\n",
+                                                                 tag);
+                        err = -EIO;
                         goto error;
+                }
+
+                if (m->req->rc == NULL) {
+                        m->req->rc = kmalloc(sizeof(struct p9_fcall) +
+                                                m->client->msize, GFP_KERNEL);
+                        if (!m->req->rc) {
+                                m->req = NULL;
+                                err = -ENOMEM;
+                                goto error;
+                        }
+                }
+                m->rbuf = (char *)m->req->rc + sizeof(struct p9_fcall);
+                memcpy(m->rbuf, m->tmp_buf, m->rsize);
+                m->rsize = n;
+        }
+
+        /* 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_MUX, "got new packet\n");
+                m->rbuf = (char *)m->req->rc + sizeof(struct p9_fcall);
+                err = p9_deserialize_fcall(m->rbuf, m->rsize, m->req->rc,
+                                                        m->client->dotu);
+                if (err < 0) {
+                        m->req = NULL;
+                        goto error;
+                }
 
 #ifdef CONFIG_NET_9P_DEBUG
                 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
                         char buf[150];
 
-                        p9_printfcall(buf, sizeof(buf), m->rcall,
+                        p9_printfcall(buf, sizeof(buf), m->req->rc,
                                 m->client->dotu);
                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
                 }
 #endif
 
-                rcall = m->rcall;
-                rbuf = m->rbuf;
-                if (m->rpos > n) {
-                        m->rcall = kmalloc(sizeof(struct p9_fcall) +
-                                                m->client->msize, GFP_KERNEL);
-                        if (!m->rcall) {
-                                err = -ENOMEM;
-                                goto error;
-                        }
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
+                                        m->req->rc->id, m->req->rc->tag);
 
-                        m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
-                        memmove(m->rbuf, rbuf + n, m->rpos - n);
-                        m->rpos -= n;
-                } else {
-                        m->rcall = NULL;
-                        m->rbuf = NULL;
-                        m->rpos = 0;
-                }
+                m->rbuf = NULL;
+                m->rpos = 0;
+                m->rsize = 0;
 
-                P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
-                                                        rcall->id, rcall->tag);
+                if (m->req->status != REQ_STATUS_FLSH) {
+                        list_del(&m->req->req_list);
+                        m->req->status = REQ_STATUS_RCVD;
+                }
 
-                req = p9_tag_lookup(m->client, rcall->tag);
+                process_request(m, m->req);
 
-                if (req) {
-                        if (req->status != REQ_STATUS_FLSH) {
-                                list_del(&req->req_list);
-                                req->status = REQ_STATUS_RCVD;
-                        }
+                if (m->req->status != REQ_STATUS_FLSH)
+                        p9_conn_rpc_cb(m->client, m->req);
 
-                        req->rc = rcall;
-                        process_request(m, req);
-
-                        if (req->status != REQ_STATUS_FLSH)
-                                p9_conn_rpc_cb(m->client, req);
-                } else {
-                        if (err >= 0 && rcall->id != P9_RFLUSH)
-                                P9_DPRINTK(P9_DEBUG_ERROR,
-                                  "unexpected response mux %p id %d tag %d\n",
-                                  m, rcall->id, rcall->tag);
-                        kfree(rcall);
-                }
+                m->req = NULL;
         }
 
         if (!list_empty(&m->req_list)) {
@@ -470,7 +474,6 @@ static void p9_read_work(struct work_struct *work)
                 clear_bit(Rworksched, &m->wsched);
 
         return;
-
 error:
         p9_conn_cancel(m, err);
         clear_bit(Rworksched, &m->wsched);