On Tue, 10 Apr 2007, Samuel Ortiz wrote:
> Hi Guennadi,
>
> The patch below schedules irnet_flow_indication() asynchronously. Could
> you please give it a try (it builds, but I couldn't test it...) ? :
Ok, your patch (still below) works too (now that I fixed that state
machine race, btw, we still have to decide on the final form how it goes
in the mainline) __after__ you also add the line
+ INIT_WORK(&new->irnet_flow_work, irttp_flow_restart);
in irttp_dup() (remember spinlock_init()?:-)), otherwise it oopses.
Generally, I like your patch better than mine to ppp_generic.c, where I
explicitly check if a recursion is occurring. Still, I am a bit concerned
about introducing yet another execution context into irda... We have seen
a couple of locking issues there already in the last 2-3 months especially
under rt-preempt... Would you be able to run some tests too? I will be
testing it too, but don't know how much longer and how intensively. Do you
think we might get some new problems with this new context?
Thanks
Guennadi
>
> diff --git a/include/net/irda/irttp.h b/include/net/irda/irttp.h
> index a899e58..941f0f1 100644
> --- a/include/net/irda/irttp.h
> +++ b/include/net/irda/irttp.h
> @@ -128,6 +128,7 @@ struct tsap_cb {
>
> struct net_device_stats stats;
> struct timer_list todo_timer;
> + struct work_struct irnet_flow_work; /* irttp asynchronous flow restart */
>
> __u32 max_seg_size; /* Max data that fit into an IrLAP frame */
> __u8 max_header_size;
> diff --git a/net/irda/irnet/irnet.h b/net/irda/irnet/irnet.h
> diff --git a/net/irda/irttp.c b/net/irda/irttp.c
> index 7069e4a..a0d0f26 100644
> --- a/net/irda/irttp.c
> +++ b/net/irda/irttp.c
> @@ -367,6 +367,29 @@ static int irttp_param_max_sdu_size(void *instance, irda_param_t *param,
> /*************************** CLIENT CALLS ***************************/
> /************************** LMP CALLBACKS **************************/
> /* Everything is happily mixed up. Waiting for next clean up - Jean II */
> +static void irttp_flow_restart(struct work_struct *work)
> +{
> + struct tsap_cb * self =
> + container_of(work, struct tsap_cb, irnet_flow_work);
> +
> + if (self == NULL)
> + return;
> +
> + /* Check if we can accept more frames from client. */
> + if ((self->tx_sdu_busy) &&
> + (skb_queue_len(&self->tx_queue) < TTP_TX_LOW_THRESHOLD) &&
> + (!self->close_pend)) {
> + if (self->notify.flow_indication)
> + self->notify.flow_indication(self->notify.instance,
> + self, FLOW_START);
> +
> + /* self->tx_sdu_busy is the state of the client.
> + * We don't really have a race here, but it's always safer
> + * to update our state after the client - Jean II */
> + self->tx_sdu_busy = FALSE;
> + }
> +}
> +
>
> /*
> * Function irttp_open_tsap (stsap, notify)
> @@ -402,6 +425,8 @@ struct tsap_cb *irttp_open_tsap(__u8 stsap_sel, int credit, notify_t *notify)
> self->todo_timer.data = (unsigned long) self;
> self->todo_timer.function = &irttp_todo_expired;
>
> + INIT_WORK(&self->irnet_flow_work, irttp_flow_restart);
> +
> /* Initialize callbacks for IrLMP to use */
> irda_notify_init(&ttp_notify);
> ttp_notify.connect_confirm = irttp_connect_confirm;
> @@ -761,25 +786,10 @@ static void irttp_run_tx_queue(struct tsap_cb *self)
> self->stats.tx_packets++;
> }
>
> - /* Check if we can accept more frames from client.
> - * We don't want to wait until the todo timer to do that, and we
> - * can't use tasklets (grr...), so we are obliged to give control
> - * to client. That's ok, this test will be true not too often
> - * (max once per LAP window) and we are called from places
> - * where we can spend a bit of time doing stuff. - Jean II */
> if ((self->tx_sdu_busy) &&
> (skb_queue_len(&self->tx_queue) < TTP_TX_LOW_THRESHOLD) &&
> (!self->close_pend))
> - {
> - if (self->notify.flow_indication)
> - self->notify.flow_indication(self->notify.instance,
> - self, FLOW_START);
> -
> - /* self->tx_sdu_busy is the state of the client.
> - * We don't really have a race here, but it's always safer
> - * to update our state after the client - Jean II */
> - self->tx_sdu_busy = FALSE;
> - }
> + schedule_work(&self->irnet_flow_work);
>
> /* Reset lock */
> self->tx_queue_lock = 0;
>
>
>
---------------------------------
Guennadi Liakhovetski, Ph.D.
DSA Daten- und Systemtechnik GmbH
Pascalstr. 28
D-52076 Aachen
Germany
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