On Wed, Aug 08, 2007 at 11:33:00AM +0200, Heiko Carstens wrote:
> From: Heiko Carstens <[email protected]>
>
> For architectures that don't have a volatile atomic_ts constructs like
> while (atomic_read(&something)); might result in endless loops since a
> barrier() is missing which forces the compiler to generate code that
> actually reads memory contents.
> Fix this in ipvs by using the IP_VS_WAIT_WHILE macro which resolves to
> while (expr) { cpu_relax(); }
> (why isn't this open coded btw?)
>
> Cc: Wensong Zhang <[email protected]>
> Cc: Simon Horman <[email protected]>
> Cc: David Miller <[email protected]>
> Cc: Martin Schwidefsky <[email protected]>
> Signed-off-by: Heiko Carstens <[email protected]>
> ---
>
> Just saw this while grepping for atomic_reads in a while loops.
> Maybe we should re-add the volatile to atomic_t. Not sure.
This looks good to me. A little wile back I noticed a few places
where IP_VS_WAIT_WHILE seemed to be curiously unused, then I got
distracted...
Signed-off-by: Simon Horman <[email protected]>
>
> net/ipv4/ipvs/ip_vs_ctl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> Index: linux-2.6/net/ipv4/ipvs/ip_vs_ctl.c
> ===================================================================
> --- linux-2.6.orig/net/ipv4/ipvs/ip_vs_ctl.c
> +++ linux-2.6/net/ipv4/ipvs/ip_vs_ctl.c
> @@ -909,7 +909,7 @@ ip_vs_edit_dest(struct ip_vs_service *sv
> write_lock_bh(&__ip_vs_svc_lock);
>
> /* Wait until all other svc users go away */
> - while (atomic_read(&svc->usecnt) > 1) {};
> + IP_VS_WAIT_WHILE(atomic_read(&svc->usecnt) > 1);
>
> /* call the update_service, because server weight may be changed */
> svc->scheduler->update_service(svc);
--
Horms
H: http://www.vergenet.net/~horms/
W: http://www.valinux.co.jp/en/
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