Re: [RFCv1 2/3] Bluetooth: Simplify num_comp_pkts_evt function

[Emeltchenko Andrei <Andrei.Emeltchenko.news@gmail.com>]

Hi Marcel,

On Wed, Dec 07, 2011 at 10:20:57AM +0200, Marcel Holtmann wrote:
> Hi Andrei,
> 
> > > > > > Simplify function and remove fourth level of indentation.
> > > > > > 
> > > > > > Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
> > > > > > ---
> > > > > >  net/bluetooth/hci_event.c |   43 +++++++++++++++++++++++++------------------
> > > > > >  1 files changed, 25 insertions(+), 18 deletions(-)
> > > > > > 
> > > > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > > > > index 273e1cb..fd7e6b5 100644
> > > > > > --- a/net/bluetooth/hci_event.c
> > > > > > +++ b/net/bluetooth/hci_event.c
> > > > > > @@ -2288,28 +2288,35 @@ static inline void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct sk_buff *s
> > > > > >  		count  = get_unaligned_le16(ptr++);
> > > > > 
> > > > > actually we first need a cleanup of this function. This part is
> > > > > horrible. It works because of our ptr cast to uint16, but we should
> > > > > actually use a proper struct here. Maybe an info struct like we use for
> > > > > inquiry result might be helpful here.
> > > > 
> > > > Something like the code below?
> > > > 
> > > > diff --git a/include/net/bluetooth/hci.h b/include/net/bluetooth/hci.h
> > > > index e33e468..403974c 100644
> > > > --- a/include/net/bluetooth/hci.h
> > > > +++ b/include/net/bluetooth/hci.h
> > > > @@ -1018,9 +1018,14 @@ struct hci_ev_role_change {
> > > >  } __packed;
> > > >  
> > > >  #define HCI_EV_NUM_COMP_PKTS           0x13
> > > > +struct hci_comp_pkts_info {
> > > > +       __le16   handle;
> > > > +       __le16   count;
> > > > +} __packed;
> > > > +
> > > >  struct hci_ev_num_comp_pkts {
> > > >         __u8     num_hndl;
> > > > -       /* variable length part */
> > > > +       struct hci_comp_pkts_info handles[0];
> > > >  } __packed;
> > > >  
> > > >  #define HCI_EV_MODE_CHANGE             0x14
> > > > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > > > index 238fb65..079b94f 100644
> > > > --- a/net/bluetooth/hci_event.c
> > > > +++ b/net/bluetooth/hci_event.c
> > > > @@ -2273,26 +2273,27 @@ static inline void hci_role_change_evt(struct
> > > > hci_dev *hdev, struct sk_buff *skb
> > > >  static inline void hci_num_comp_pkts_evt(struct hci_dev *hdev, struct
> > > > sk_buff *skb)
> > > >  {
> > > >         struct hci_ev_num_comp_pkts *ev = (void *) skb->data;
> > > > -       __le16 *ptr;
> > > > +       struct hci_comp_pkts_info *info;
> > > >         int i;
> > > >  
> > > >         skb_pull(skb, sizeof(*ev));
> > > >  
> > > >         BT_DBG("%s num_hndl %d", hdev->name, ev->num_hndl);
> > > >  
> > > > -       if (skb->len < ev->num_hndl * 4) {
> > > > +       if (skb->len < ev->num_hndl * sizeof(*info)) {
> > > >                 BT_DBG("%s bad parameters", hdev->name);
> > > >                 return;
> > > >         }
> > > >  
> > > >         tasklet_disable(&hdev->tx_task);
> > > >  
> > > > -       for (i = 0, ptr = (__le16 *) skb->data; i < ev->num_hndl; i++) {
> > > > +       for (i = 0; i < ev->num_hndl; i++) {
> > > 
> > > 		struct hci_comp_pkts_info *info = &ev->handles[i];
> > 
> > I was actually using "info" to eliminate magic size above, otherwise I have
> > to use long "sizeof(struct hci_comp_pkts_info)". This of course might be
> > done in a separate trivial patch.
> 
> you actually lost me here. Just assign the info struct pointer and then
> use it. My point was just to move the variable location localized to its
> scope of usage.
> 
> > > >                 struct hci_conn *conn;
> > > >                 __u16  handle, count;
> > > >  
> > > > -               handle = get_unaligned_le16(ptr++);
> > > > -               count  = get_unaligned_le16(ptr++);
> > > > +               info = &ev->handles[i];
> > > > +               handle = __le16_to_cpu(info->handle);
> > > > +               count  = __le16_to_cpu(info->count);
> > > >  
> > > >                 conn = hci_conn_hash_lookup_handle(hdev, handle);
> > > >                 if (!conn)
> > > 
> > > And you need to remove the skb_pull above since otherwise you are
> > > pointing to the wrong memory location.
> > 
> > Sorry, cannot get this. I assign "ev" before skb_pull, this should not be a
> > problem.
> 
> You are fully right. Nevertheless the skb_pull becomes useless now. So
> just remove it.

I will remove it in a separate patch since it is used in a packet size check.

Best regards 
Andrei Emeltchenko