kern/118093: [firewire] firewire bus reset hogs CPU, causing data to be lost

[Dieter]

In message <1231181797.21260.8.camel at localhost.localdomain>, Sean Bruno writes:

> @@ -1388,6 +1387,7 @@
>  	struct fw_device *fwdev;
>  
>  	s = splfw();
> +	FW_GLOCK(fc);
>  	fc->status = FWBUSEXPLORE;
>  
>  	/* Invalidate all devices, just after bus reset. */
> @@ -1396,6 +1396,7 @@
>  			fwdev->status = FWDEVINVAL;
>  			fwdev->rcnt = 0;
>  		}
> +	FW_GUNLOCK(fc);
>  	splx(s);
>  
>  	wakeup((void *)fc);

If the (null these days) spl calls have been replaced with FW_GLOCK/FW_GUNLOCK
calls, can the spl calls be removed now?

> @@ -1922,6 +1924,8 @@
>  	u_int i;
>  	struct firewire_comm *fc = (struct firewire_comm *)sc;
>  
> +	FW_GLOCK(fc);
> +	FW_GUNLOCK(fc);
>  	if (stat & OHCI_INT_DMA_IR) {
>  		irstat = atomic_readandclear_int(&sc->irstat);
>  		for(i = 0; i < fc->nisodma ; i++){

This needs to be reviewed by someone who understands what is protected by
getting a lock and then immediately releasing it.  I have no clue.

> @@ -1969,8 +1973,8 @@
>  			OWRITE(sc, OHCI_LNKCTLCLR, OHCI_CNTL_CYCTIMER);
>  #endif
>  			OWRITE(sc, FWOHCI_INTMASKCLR,  OHCI_INT_CYC_LOST);
> -			device_printf(fc->dev, "too many cycle lost, "
> -			 "no cycle master presents?\n");
> +			device_printf(fc->dev, "%s: too many cycle lost, "
> +			 "no cycle master presents?\n", __func__);
>  		}

Should this be "too many cycles lost, " and  "no cycle master present?\n"

>  	uint32_t fun;
>  
> +	FW_GLOCK(fc);
>  	device_printf(fc->dev, "Initiate bus reset\n");
>  	sc = (struct fwohci_softc *)fc;
>  
> @@ -2487,6 +2495,7 @@
>  	fun |= FW_PHY_ISBR | FW_PHY_RHB;
>  	fun = fwphy_wrdata(sc, FW_PHY_ISBR_REG, fun);
>  #endif
> +	FW_GUNLOCK(fc);
>  }

Does the lock need to protect the printf?