9p: trans_fd, read rework to use p9_parse_header

Most of the changes here are no-op and just renaming to use a
fcall struct, needed for p9_parse_header

It fixes the unaligned memory access to read the tag and defers to
common functions for part of the protocol knowledge (although header
length is still hard-coded...)

Reported-By: Rob Landley <rob@landley.net>
Signed-Off-By: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

1 files changed, 40 insertions, 35 deletions

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index bced8c074c12..a270dcc4ad9a 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -108,9 +108,7 @@ struct p9_poll_wait {
  * @unsent_req_list: accounting for requests that haven't been sent
  * @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
+ * @rc: temporary fcall for reading current frame
  * @wpos: write position for current frame
  * @wsize: amount of data to write for current frame
  * @wbuf: current write buffer
@@ -131,9 +129,7 @@ struct p9_conn {
         struct list_head unsent_req_list;
         struct p9_req_t *req;
         char tmp_buf[7];
-        int rsize;
-        int rpos;
-        char *rbuf;
+        struct p9_fcall rc;
         int wpos;
         int wsize;
         char *wbuf;
@@ -305,49 +301,56 @@ static void p9_read_work(struct work_struct *work)
         if (m->err < 0)
                 return;
 
-        p9_debug(P9_DEBUG_TRANS, "start mux %p pos %d\n", m, m->rpos);
+        p9_debug(P9_DEBUG_TRANS, "start mux %p pos %zd\n", m, m->rc.offset);
 
-        if (!m->rbuf) {
-                m->rbuf = m->tmp_buf;
-                m->rpos = 0;
-                m->rsize = 7; /* start by reading header */
+        if (!m->rc.sdata) {
+                m->rc.sdata = m->tmp_buf;
+                m->rc.offset = 0;
+                m->rc.capacity = 7; /* start by reading header */
         }
 
         clear_bit(Rpending, &m->wsched);
-        p9_debug(P9_DEBUG_TRANS, "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->rsize - m->rpos);
+        p9_debug(P9_DEBUG_TRANS, "read mux %p pos %zd size: %zd = %zd\n",
+                 m, m->rc.offset, m->rc.capacity,
+                 m->rc.capacity - m->rc.offset);
+        err = p9_fd_read(m->client, m->rc.sdata + m->rc.offset,
+                         m->rc.capacity - m->rc.offset);
         p9_debug(P9_DEBUG_TRANS, "mux %p got %d bytes\n", m, err);
-        if (err == -EAGAIN) {
+        if (err == -EAGAIN)
                 goto end_clear;
-        }
 
         if (err <= 0)
                 goto error;
 
-        m->rpos += err;
+        m->rc.offset += err;
 
-        if ((!m->req) && (m->rpos == m->rsize)) { /* header read in */
-                u16 tag;
+        /* header read in */
+        if ((!m->req) && (m->rc.offset == m->rc.capacity)) {
                 p9_debug(P9_DEBUG_TRANS, "got new header\n");
 
-                n = le32_to_cpu(*(__le32 *) m->rbuf); /* read packet size */
-                if (n >= m->client->msize) {
+                err = p9_parse_header(&m->rc, NULL, NULL, NULL, 0);
+                if (err) {
                         p9_debug(P9_DEBUG_ERROR,
-                                 "requested packet size too big: %d\n", n);
+                                 "error parsing header: %d\n", err);
+                        goto error;
+                }
+
+                if (m->rc.size >= m->client->msize) {
+                        p9_debug(P9_DEBUG_ERROR,
+                                 "requested packet size too big: %d\n",
+                                 m->rc.size);
                         err = -EIO;
                         goto error;
                 }
 
-                tag = le16_to_cpu(*(__le16 *) (m->rbuf+5)); /* read tag */
                 p9_debug(P9_DEBUG_TRANS,
-                         "mux %p pkt: size: %d bytes tag: %d\n", m, n, tag);
+                         "mux %p pkt: size: %d bytes tag: %d\n",
+                         m, m->rc.size, m->rc.tag);
 
-                m->req = p9_tag_lookup(m->client, tag);
+                m->req = p9_tag_lookup(m->client, m->rc.tag);
                 if (!m->req || (m->req->status != REQ_STATUS_SENT)) {
                         p9_debug(P9_DEBUG_ERROR, "Unexpected packet tag %d\n",
-                                 tag);
+                                 m->rc.tag);
                         err = -EIO;
                         goto error;
                 }
@@ -361,13 +364,15 @@ static void p9_read_work(struct work_struct *work)
                                 goto error;
                         }
                 }
-                m->rbuf = (char *)m->req->rc + sizeof(struct p9_fcall);
-                memcpy(m->rbuf, m->tmp_buf, m->rsize);
-                m->rsize = n;
+                m->rc.sdata = (char *)m->req->rc + sizeof(struct p9_fcall);
+                memcpy(m->rc.sdata, m->tmp_buf, m->rc.capacity);
+                m->rc.capacity = m->rc.size;
         }
 
-        /* not an else because some packets (like clunk) have no payload */
-        if ((m->req) && (m->rpos == m->rsize)) { /* packet is read in */
+        /* packet is read in
+         * not an else because some packets (like clunk) have no payload
+         */
+        if ((m->req) && (m->rc.offset == m->rc.capacity)) {
                 p9_debug(P9_DEBUG_TRANS, "got new packet\n");
                 spin_lock(&m->client->lock);
                 if (m->req->status != REQ_STATUS_ERROR)
@@ -375,9 +380,9 @@ static void p9_read_work(struct work_struct *work)
                 list_del(&m->req->req_list);
                 spin_unlock(&m->client->lock);
                 p9_client_cb(m->client, m->req, status);
-                m->rbuf = NULL;
-                m->rpos = 0;
-                m->rsize = 0;
+                m->rc.sdata = NULL;
+                m->rc.offset = 0;
+                m->rc.capacity = 0;
                 m->req = NULL;
         }