Re: [RFC,PATCH 3/4] Change synchronize_kernel to _rcu and _sched

[Francois Romieu <romieu@fr.zoreil.com>]

Paul E. McKenney <paulmck@us.ibm.com> :
> This patch changes calls to synchronize_kernel(), deprecated in the
> earlier "Deprecate synchronize_kernel, GPL replacement" patch to
> instead call the new synchronize_rcu() and synchronize_sched() APIs.
[...]
> diff -urpN -X dontdiff linux-2.6.12-rc1/drivers/net/r8169.c linux-2.6.12-rc1-bettersk/drivers/net/r8169.c
> --- linux-2.6.12-rc1/drivers/net/r8169.c	Thu Mar 31 09:53:08 2005
> +++ linux-2.6.12-rc1-bettersk/drivers/net/r8169.c	Fri Apr  1 21:41:38 2005
> @@ -2385,7 +2385,7 @@ core_down:
>  	}
>  
>  	/* Give a racing hard_start_xmit a few cycles to complete. */
> -	synchronize_kernel();
> +	synchronize_sched();  /* FIXME: should this be synchronize_irq()? */
>  
>  	/*
>  	 * And now for the 50k$ question: are IRQ disabled or not ?

(answering the FIXME)

The race with the irq is handled somewhere else. As the comment suggests,
this part is racing with the hard_start_xmit() handler. If I read correctly
net/core/dev.c::dev_queue_xmit, the code above simply needs the new
synchronize_rcu().

--
Ueimor
-
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