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net/9p: handle correctly interrupted 9P requests
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Currently the 9p code crashes when a operation is interrupted, i.e. for
example when the user presses ^C while reading from a file.

This patch fixes the code that is responsible for interruption and flushing
of 9P operations.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
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Latchesar Ionkov authored and Eric Van Hensbergen committed Apr 5, 2009
1 parent 742b11a commit 1bab88b
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Showing 5 changed files with 30 additions and 61 deletions.
1 change: 0 additions & 1 deletion include/net/9p/client.h
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Original file line number Diff line number Diff line change
Expand Up @@ -98,7 +98,6 @@ enum p9_req_status_t {
struct p9_req_t {
int status;
int t_err;
u16 flush_tag;
wait_queue_head_t *wq;
struct p9_fcall *tc;
struct p9_fcall *rc;
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74 changes: 19 additions & 55 deletions net/9p/client.c
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Original file line number Diff line number Diff line change
Expand Up @@ -203,7 +203,6 @@ static struct p9_req_t *p9_tag_alloc(struct p9_client *c, u16 tag)
p9pdu_reset(req->tc);
p9pdu_reset(req->rc);

req->flush_tag = 0;
req->tc->tag = tag-1;
req->status = REQ_STATUS_ALLOC;

Expand Down Expand Up @@ -324,35 +323,9 @@ static void p9_free_req(struct p9_client *c, struct p9_req_t *r)
*/
void p9_client_cb(struct p9_client *c, struct p9_req_t *req)
{
struct p9_req_t *other_req;
unsigned long flags;

P9_DPRINTK(P9_DEBUG_MUX, " tag %d\n", req->tc->tag);

if (req->status == REQ_STATUS_ERROR)
wake_up(req->wq);

if (req->flush_tag) { /* flush receive path */
P9_DPRINTK(P9_DEBUG_9P, "<<< RFLUSH %d\n", req->tc->tag);
spin_lock_irqsave(&c->lock, flags);
other_req = p9_tag_lookup(c, req->flush_tag);
if (other_req->status != REQ_STATUS_FLSH) /* stale flush */
spin_unlock_irqrestore(&c->lock, flags);
else {
other_req->status = REQ_STATUS_FLSHD;
spin_unlock_irqrestore(&c->lock, flags);
wake_up(other_req->wq);
}
p9_free_req(c, req);
} else { /* normal receive path */
P9_DPRINTK(P9_DEBUG_MUX, "normal: tag %d\n", req->tc->tag);
spin_lock_irqsave(&c->lock, flags);
if (req->status != REQ_STATUS_FLSHD)
req->status = REQ_STATUS_RCVD;
spin_unlock_irqrestore(&c->lock, flags);
wake_up(req->wq);
P9_DPRINTK(P9_DEBUG_MUX, "wakeup: %d\n", req->tc->tag);
}
wake_up(req->wq);
P9_DPRINTK(P9_DEBUG_MUX, "wakeup: %d\n", req->tc->tag);
}
EXPORT_SYMBOL(p9_client_cb);

Expand Down Expand Up @@ -486,9 +459,15 @@ static int p9_client_flush(struct p9_client *c, struct p9_req_t *oldreq)
if (IS_ERR(req))
return PTR_ERR(req);

req->flush_tag = oldtag;

/* we don't free anything here because RPC isn't complete */
/* if we haven't received a response for oldreq,
remove it from the list. */
spin_lock(&c->lock);
if (oldreq->status == REQ_STATUS_FLSH)
list_del(&oldreq->req_list);
spin_unlock(&c->lock);

p9_free_req(c, req);
return 0;
}

Expand All @@ -509,7 +488,6 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
struct p9_req_t *req;
unsigned long flags;
int sigpending;
int flushed = 0;

P9_DPRINTK(P9_DEBUG_MUX, "client %p op %d\n", c, type);

Expand Down Expand Up @@ -546,42 +524,28 @@ p9_client_rpc(struct p9_client *c, int8_t type, const char *fmt, ...)
goto reterr;
}

/* if it was a flush we just transmitted, return our tag */
if (type == P9_TFLUSH)
return req;
again:
P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d\n", req->wq, tag);
err = wait_event_interruptible(*req->wq,
req->status >= REQ_STATUS_RCVD);
P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d returned %d (flushed=%d)\n",
req->wq, tag, err, flushed);
P9_DPRINTK(P9_DEBUG_MUX, "wait %p tag: %d returned %d\n",
req->wq, tag, err);

if (req->status == REQ_STATUS_ERROR) {
P9_DPRINTK(P9_DEBUG_ERROR, "req_status error %d\n", req->t_err);
err = req->t_err;
} else if (err == -ERESTARTSYS && flushed) {
P9_DPRINTK(P9_DEBUG_MUX, "flushed - going again\n");
goto again;
} else if (req->status == REQ_STATUS_FLSHD) {
P9_DPRINTK(P9_DEBUG_MUX, "flushed - erestartsys\n");
err = -ERESTARTSYS;
}

if ((err == -ERESTARTSYS) && (c->status == Connected) && (!flushed)) {
if ((err == -ERESTARTSYS) && (c->status == Connected)) {
P9_DPRINTK(P9_DEBUG_MUX, "flushing\n");
spin_lock_irqsave(&c->lock, flags);
if (req->status == REQ_STATUS_SENT)
req->status = REQ_STATUS_FLSH;
spin_unlock_irqrestore(&c->lock, flags);
sigpending = 1;
flushed = 1;
clear_thread_flag(TIF_SIGPENDING);

if (c->trans_mod->cancel(c, req)) {
err = p9_client_flush(c, req);
if (err == 0)
goto again;
}
if (c->trans_mod->cancel(c, req))
p9_client_flush(c, req);

/* if we received the response anyway, don't signal error */
if (req->status == REQ_STATUS_RCVD)
err = 0;
}

if (sigpending) {
Expand Down
14 changes: 9 additions & 5 deletions net/9p/trans_fd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -213,8 +213,8 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
spin_unlock_irqrestore(&m->client->lock, flags);

list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
list_del(&req->req_list);
P9_DPRINTK(P9_DEBUG_ERROR, "call back req %p\n", req);
list_del(&req->req_list);
p9_client_cb(m->client, req);
}
}
Expand Down Expand Up @@ -336,7 +336,8 @@ static void p9_read_work(struct work_struct *work)
"mux %p pkt: size: %d bytes tag: %d\n", m, n, tag);

m->req = p9_tag_lookup(m->client, tag);
if (!m->req) {
if (!m->req || (m->req->status != REQ_STATUS_SENT &&
m->req->status != REQ_STATUS_FLSH)) {
P9_DPRINTK(P9_DEBUG_ERROR, "Unexpected packet tag %d\n",
tag);
err = -EIO;
Expand All @@ -361,10 +362,11 @@ static void p9_read_work(struct work_struct *work)
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);
if (m->req->status != REQ_STATUS_ERROR)
m->req->status = REQ_STATUS_RCVD;
list_del(&m->req->req_list);
spin_unlock(&m->client->lock);
p9_client_cb(m->client, m->req);

m->rbuf = NULL;
m->rpos = 0;
m->rsize = 0;
Expand Down Expand Up @@ -454,6 +456,7 @@ static void p9_write_work(struct work_struct *work)
req = list_entry(m->unsent_req_list.next, struct p9_req_t,
req_list);
req->status = REQ_STATUS_SENT;
P9_DPRINTK(P9_DEBUG_TRANS, "move req %p\n", req);
list_move_tail(&req->req_list, &m->req_list);

m->wbuf = req->tc->sdata;
Expand Down Expand Up @@ -683,12 +686,13 @@ static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)
P9_DPRINTK(P9_DEBUG_TRANS, "client %p req %p\n", client, req);

spin_lock(&client->lock);
list_del(&req->req_list);

if (req->status == REQ_STATUS_UNSENT) {
list_del(&req->req_list);
req->status = REQ_STATUS_FLSHD;
ret = 0;
}
} else if (req->status == REQ_STATUS_SENT)
req->status = REQ_STATUS_FLSH;

spin_unlock(&client->lock);

Expand Down
1 change: 1 addition & 0 deletions net/9p/trans_rdma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -295,6 +295,7 @@ handle_recv(struct p9_client *client, struct p9_trans_rdma *rdma,
goto err_out;

req->rc = c->rc;
req->status = REQ_STATUS_RCVD;
p9_client_cb(client, req);

return;
Expand Down
1 change: 1 addition & 0 deletions net/9p/trans_virtio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,7 @@ static void req_done(struct virtqueue *vq)
P9_DPRINTK(P9_DEBUG_TRANS, ": rc %p\n", rc);
P9_DPRINTK(P9_DEBUG_TRANS, ": lookup tag %d\n", rc->tag);
req = p9_tag_lookup(chan->client, rc->tag);
req->status = REQ_STATUS_RCVD;
p9_client_cb(chan->client, req);
}
}
Expand Down

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