From: Paul E. McKenney Date: Tue, 22 Apr 2008 01:12:33 +0000 (-0700) Subject: SELinux fixups needed for preemptable RCU from -rt X-Git-Tag: v2.6.26-rc1~1103^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=618442509128fe4514be94de70ce54075cd9a706;p=linux-2.6 SELinux fixups needed for preemptable RCU from -rt The attached patch needs to move from -rt to mainline given preemptable RCU. This patch fixes SELinux code that implicitly assumes that disabling preemption prevents an RCU grace period from completing, an assumption that is valid for Classic RCU, but not necessarily for preemptable RCU. Explicit rcu_read_lock() calls are thus added. Signed-off-by: Paul E. McKenney Acked-by: Steven Rostedt Signed-off-by: James Morris --- diff --git a/security/selinux/avc.c b/security/selinux/avc.c index 1d69f6649b..95a8ef4a50 100644 --- a/security/selinux/avc.c +++ b/security/selinux/avc.c @@ -312,6 +312,7 @@ static inline int avc_reclaim_node(void) if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags)) continue; + rcu_read_lock(); list_for_each_entry(node, &avc_cache.slots[hvalue], list) { if (atomic_dec_and_test(&node->ae.used)) { /* Recently Unused */ @@ -319,11 +320,13 @@ static inline int avc_reclaim_node(void) avc_cache_stats_incr(reclaims); ecx++; if (ecx >= AVC_CACHE_RECLAIM) { + rcu_read_unlock(); spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); goto out; } } } + rcu_read_unlock(); spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags); } out: @@ -821,8 +824,14 @@ int avc_ss_reset(u32 seqno) for (i = 0; i < AVC_CACHE_SLOTS; i++) { spin_lock_irqsave(&avc_cache.slots_lock[i], flag); + /* + * With preemptable RCU, the outer spinlock does not + * prevent RCU grace periods from ending. + */ + rcu_read_lock(); list_for_each_entry(node, &avc_cache.slots[i], list) avc_node_delete(node); + rcu_read_unlock(); spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag); } diff --git a/security/selinux/netif.c b/security/selinux/netif.c index c658b84c31..b4e14bc0bf 100644 --- a/security/selinux/netif.c +++ b/security/selinux/netif.c @@ -239,11 +239,13 @@ static void sel_netif_kill(int ifindex) { struct sel_netif *netif; + rcu_read_lock(); spin_lock_bh(&sel_netif_lock); netif = sel_netif_find(ifindex); if (netif) sel_netif_destroy(netif); spin_unlock_bh(&sel_netif_lock); + rcu_read_unlock(); } /**