Messages in this thread Patch in this message | | | Date | Wed, 8 Aug 2007 11:33:00 +0200 | From | Heiko Carstens <> | Subject | [patch] ipvs: force read of atomic_t in while loop |
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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.
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); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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