Re: [V9fs-developer] [PATCH] net/9p: handle correctly interrupted 9P requests

From: Eric Van Hensbergen
Date: Sun Apr 05 2009 - 17:39:20 EST

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In reply to: Latchesar Ionkov: "[PATCH] net/9p: handle correctly interrupted 9P requests"
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Applied with some minor style changes to v9fs-devel.
David Miller has requested that all patches to the net tree be cc:'d
to netdev@xxxxxxxxxxxxxxxx
The other patches you sent have been applied as well.

-eric

On Thu, Apr 2, 2009 at 6:37 PM, Latchesar Ionkov <lucho@xxxxxxxxxx> wrote:
> 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@xxxxxxxxxx>
>
> diff --git a/include/net/9p/client.h b/include/net/9p/client.h
> index 4012e07..e268122 100644
> --- a/include/net/9p/client.h
> +++ b/include/net/9p/client.h
> @@ -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;
> diff --git a/net/9p/client.c b/net/9p/client.c
> index c079df6..f5634b5 100644
> --- a/net/9p/client.c
> +++ b/net/9p/client.c
> @@ -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;
>
> @@ -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);
>
> @@ -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;
> }
>
> @@ -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);
>
> @@ -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)) {
> - 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);
> + if ((err == -ERESTARTSYS) && (c->status == Connected)) {
> + P9_DPRINTK(P9_DEBUG_MUX, "flushing\n");
> 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) {
> diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
> index c613ed0..a2a1814 100644
> --- a/net/9p/trans_fd.c
> +++ b/net/9p/trans_fd.c
> @@ -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);
> }
> }
> @@ -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;
> @@ -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;
> @@ -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;
> @@ -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);
>
> diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
> index 7fa0eb2..ac49900 100644
> --- a/net/9p/trans_rdma.c
> +++ b/net/9p/trans_rdma.c
> @@ -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;
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 2d7781e..bb8579a 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -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);
> }
> }
>
> ------------------------------------------------------------------------------
> _______________________________________________
> V9fs-developer mailing list
> V9fs-developer@xxxxxxxxxxxxxxxxxxxxx
> https://lists.sourceforge.net/lists/listinfo/v9fs-developer
>
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Next message: Ingo Molnar: "[RFC PATCH] x86, oprofile: fix P4 oprofile CPU setup bug"
Previous message: Kristoffer Ericson: "ACPI on asus eeepc 701 (v2.6.28-29)"
In reply to: Latchesar Ionkov: "[PATCH] net/9p: handle correctly interrupted 9P requests"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]