From 24ce8010cd414c8c573f2b035d186a2418900546 Mon Sep 17 00:00:00 2001
From: Derrick Brashear <shadow@dementia.org>
Date: Sun, 12 Oct 2008 19:44:27 +0000
Subject: [PATCH] linux-proc-walk-locking-20081012

LICENSE IPL10
FIXES 116603

sort out rcu locking versus tasklist lock. if this fails we probably have to
disable walking entirely
---
 src/afs/afs_osi_gcpags.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/src/afs/afs_osi_gcpags.c b/src/afs/afs_osi_gcpags.c
index f5d2401638..4c552ca1d6 100644
--- a/src/afs/afs_osi_gcpags.c
+++ b/src/afs/afs_osi_gcpags.c
@@ -234,17 +234,18 @@ afs_osi_TraverseProcTable()
 {
 #if !defined(LINUX_KEYRING_SUPPORT)
     struct task_struct *p;
-#ifdef EXPORTED_TASKLIST_LOCK
-    if (&tasklist_lock)
-       read_lock(&tasklist_lock);
-#endif
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
-#ifdef EXPORTED_TASKLIST_LOCK
-    else
-#endif
-	rcu_read_lock();
-#endif
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) && defined(EXPORTED_TASKLIST_LOCK)
+    if (&tasklist_lock)
+	read_lock(&tasklist_lock);
+#endif /* EXPORTED_TASKLIST_LOCK */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) && defined(EXPORTED_TASKLIST_LOCK)
+    else
+#endif /* EXPORTED_TASKLIST_LOCK && LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) */
+	rcu_read_lock();
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) */
+    
 #ifdef DEFINED_FOR_EACH_PROCESS
     for_each_process(p) if (p->pid) {
 #ifdef STRUCT_TASK_STRUCT_HAS_EXIT_STATE
@@ -268,16 +269,16 @@ afs_osi_TraverseProcTable()
 	afs_GCPAGs_perproc_func(p);
     }
 #endif
-#ifdef EXPORTED_TASKLIST_LOCK
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) && defined(EXPORTED_TASKLIST_LOCK)
     if (&tasklist_lock)
-       read_unlock(&tasklist_lock);
-#endif
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16)
-#ifdef EXPORTED_TASKLIST_LOCK
+	read_unlock(&tasklist_lock);
+#endif /* EXPORTED_TASKLIST_LOCK */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) && defined(EXPORTED_TASKLIST_LOCK)
     else
-#endif
+#endif /* EXPORTED_TASKLIST_LOCK && LINUX_VERSION_CODE < KERNEL_VERSION(2,6,18) */
 	rcu_read_unlock();
-#endif
+#endif /* LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,16) */
 #endif
 }
 #endif