[PATCH 3/3] ipvs: flush defense_work before module unload

[Oleg Nesterov <oleg@tv-sign.ru>]

net/ipv4/ipvs/ip_vs_core.c

	module_exit
	    ip_vs_cleanup
		ip_vs_control_cleanup
		    cancel_rearming_delayed_work
	// done

This is unsafe. The module may be unloaded and the memory may be freed while
defense_work's handler is still running/preempted.

Do flush_work(&defense_work.work) after cancel_rearming_delayed_work().

Alternatively, we could add flush_work() to cancel_rearming_delayed_work(),
but note that we can't change cancel_delayed_work() in the same manner because
it may be called from atomic context.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>

--- 6.20-rc6-mm3/net/ipv4/ipvs/ip_vs_ctl.c~3_ipvs	2007-02-03 20:41:11.000000000 +0300
+++ 6.20-rc6-mm3/net/ipv4/ipvs/ip_vs_ctl.c	2007-02-10 23:14:41.000000000 +0300
@@ -2387,6 +2387,7 @@ void ip_vs_control_cleanup(void)
 	EnterFunction(2);
 	ip_vs_trash_cleanup();
 	cancel_rearming_delayed_work(&defense_work);
+	flush_work_keventd(&defense_work.work);
 	ip_vs_kill_estimator(&ip_vs_stats);
 	unregister_sysctl_table(sysctl_header);
 	proc_net_remove("ip_vs_stats");

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