Messages in this thread | | | Date | Wed, 8 Aug 2007 18:45:44 +0900 | From | Horms <> | Subject | Re: [patch] ipvs: force read of atomic_t in while loop |
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On Wed, Aug 08, 2007 at 11:33:00AM +0200, Heiko Carstens wrote: > From: Heiko Carstens <heiko.carstens@de.ibm.com> > > 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 <wensong@linux-vs.org> > Cc: Simon Horman <horms@verge.net.au> > Cc: David Miller <davem@davemloft.net> > Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> > Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> > --- > > 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 <horms@verge.net.au>
> > 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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