Hi Yuri,
* Yuri Ershov <ext-yuri.ershov@xxxxxxxxx> [2010-12-07 16:12:00 +0300]:
> Hello Gustavo,
>
> ext Gustavo F. Padovan wrote:
> > Hi Yuri,
> >
> > * Yuri Ershov <ext-yuri.ershov@xxxxxxxxx> [2010-11-25 12:55:33 +0300]:
> >
> >
> >> This patch is an addition to my previous patch for this issue.
> >> The problem is in resynchronization between two loops:
> >> 1. Main controlling loop (l2cap_connect_req, l2cap_config_req,
> >> l2cap_config_rsp, l2cap_disconnect_req, etc.)
> >> 2. Loop waiting of BT_CONNECTED state of socket (l2cap_sock_accept,
> >> bt_accept_dequeue, etc.).
> >> In case of fast sequence of connect/disconnect operations the loop #1
> >> makes several cycles, while the loop #2 only has time to make one
> >> cycle and it results crash.
> >> The aim of the patch is to skeep handling of sockets queued for
> >> deletion.
> >>
> >> Signed-off-by: Yuri Ershov <ext-yuri.ershov@xxxxxxxxx>
> >> ---
> >> net/bluetooth/af_bluetooth.c | 2 ++
> >> net/bluetooth/l2cap.c | 6 ++++--
> >> 2 files changed, 6 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> >> index c4cf3f5..f9389da 100644
> >> --- a/net/bluetooth/af_bluetooth.c
> >> +++ b/net/bluetooth/af_bluetooth.c
> >> @@ -200,6 +200,8 @@ struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock)
> >> BT_DBG("parent %p", parent);
> >>
> >> list_for_each_safe(p, n, &bt_sk(parent)->accept_q) {
> >> + if (n == p)
> >> + break;
> >>
> >
> > So in which situations (n == p), or (p == p->next)? That should happen only
> > when p is the only element in the list, then p == head, right?
> >
> The (n == p) is in situation, when sk is unlinked by task responsible
> for handling connect/disconnect requests while the "bt_accept_dequeue".
> This condition is indirect checking of sk validity.
Why not using a list lock here instead? Fits a way better.
--
Gustavo F. Padovan
http://profusion.mobi
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