From: Julian Anastasov <ja@ssi.bg>
Date: Mon, 29 Jun 2015 18:51:40 +0000 (+0300)
Subject: ipvs: fix crash if scheduler is changed
X-Git-Tag: omap-for-v4.3/fixes-merge-window~158^2~36^2~1^2~3
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=05f00505a89acd21f5d0d20f5797dfbc4cf85243;p=pandora-kernel.git

ipvs: fix crash if scheduler is changed

I overlooked the svc->sched_data usage from schedulers
when the services were converted to RCU in 3.10. Now
the rare ipvsadm -E command can change the scheduler
but due to the reverse order of ip_vs_bind_scheduler
and ip_vs_unbind_scheduler we provide new sched_data
to the old scheduler resulting in a crash.

To fix it without changing the scheduler methods we
have to use synchronize_rcu() only for the editing case.
It means all svc->scheduler readers should expect a
NULL value. To avoid breakage for the service listing
and ipvsadm -R we can use the "none" name to indicate
that scheduler is not assigned, a state when we drop
new connections.

Reported-by: Alexander Vasiliev <a.vasylev@404-group.com>
Fixes: ceec4c381681 ("ipvs: convert services to rcu")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>
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