From 8ab19ea36c5c5340ff598e4d15fc084eb65671dc Mon Sep 17 00:00:00 2001 From: Sven Wegener Date: Sun, 10 Aug 2008 09:17:59 +0000 Subject: [PATCH] ipvs: Fix possible deadlock in estimator code 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 Cc: stable Acked-by: Simon Horman --- net/ipv4/ipvs/ip_vs_est.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv4/ipvs/ip_vs_est.c b/net/ipv4/ipvs/ip_vs_est.c index bc04eedd6dbb..1d6e58e502fd 100644 --- a/net/ipv4/ipvs/ip_vs_est.c +++ b/net/ipv4/ipvs/ip_vs_est.c @@ -170,8 +170,11 @@ 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); } -- 2.20.1