From: Sven Wegener Date: Thu, 14 Aug 2008 03:55:22 +0000 (+0000) Subject: ipvs: Fix possible deadlock in estimator code X-Git-Tag: v2.6.25.16~33 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1cc2f16f28ccfc4c0b477e3b0de7b89817876938;p=karo-tx-linux.git ipvs: Fix possible deadlock in estimator code commit 8ab19ea36c5c5340ff598e4d15fc084eb65671dc upstream There is a slight chance for a deadlock in the estimator code. We can't call del_timer_sync() while holding our lock, as the timer might be active and spinning for the lock on another cpu. Work around this issue by using try_to_del_timer_sync() and releasing the lock. We could actually delete the timer outside of our lock, as the add and kill functions are only every called from userspace via [gs]etsockopt() and are serialized by a mutex, but better make this explicit. Signed-off-by: Sven Wegener Acked-by: Simon Horman Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/ipv4/ipvs/ip_vs_est.c b/net/ipv4/ipvs/ip_vs_est.c index dfa0d713c801..f97ffc5a6b8a 100644 --- a/net/ipv4/ipvs/ip_vs_est.c +++ b/net/ipv4/ipvs/ip_vs_est.c @@ -172,8 +172,11 @@ void ip_vs_kill_estimator(struct ip_vs_stats *stats) kfree(est); killed++; } - if (killed && est_list == NULL) - del_timer_sync(&est_timer); + while (killed && !est_list && try_to_del_timer_sync(&est_timer) < 0) { + write_unlock_bh(&est_lock); + cpu_relax(); + write_lock_bh(&est_lock); + } write_unlock_bh(&est_lock); }