Pull model-name into release branch

[linux-2.6-microblaze.git] / kernel / cpuset.c

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1535af3..4ea6f0d 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -18,7 +18,6 @@
  *  distribution for more details.
  */
 
-#include <linux/config.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/cpuset.h>
@@ -763,6 +762,8 @@ static int validate_change(const struct cpuset *cur, const struct cpuset *trial)
  *
  * Call with manage_mutex held.  May nest a call to the
  * lock_cpu_hotplug()/unlock_cpu_hotplug() pair.
+ * Must not be called holding callback_mutex, because we must
+ * not call lock_cpu_hotplug() while holding callback_mutex.
  */
 
 static void update_cpu_domains(struct cpuset *cur)
@@ -782,7 +783,7 @@ static void update_cpu_domains(struct cpuset *cur)
                if (is_cpu_exclusive(c))
                        cpus_andnot(pspan, pspan, c->cpus_allowed);
        }
-       if (is_removed(cur) || !is_cpu_exclusive(cur)) {
+       if (!is_cpu_exclusive(cur)) {
                cpus_or(pspan, pspan, cur->cpus_allowed);
                if (cpus_equal(pspan, cur->cpus_allowed))
                        return;
@@ -815,6 +816,10 @@ static int update_cpumask(struct cpuset *cs, char *buf)
        struct cpuset trialcs;
        int retval, cpus_unchanged;
 
+       /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
+       if (cs == &top_cpuset)
+               return -EACCES;
+
        trialcs = *cs;
        retval = cpulist_parse(buf, trialcs.cpus_allowed);
        if (retval < 0)
@@ -1064,7 +1069,7 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf)
 }
 
 /*
- * Frequency meter - How fast is some event occuring?
+ * Frequency meter - How fast is some event occurring?
  *
  * These routines manage a digitally filtered, constant time based,
  * event frequency meter.  There are four routines:
@@ -1918,6 +1923,17 @@ static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode)
        return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR);
 }
 
+/*
+ * Locking note on the strange update_flag() call below:
+ *
+ * If the cpuset being removed is marked cpu_exclusive, then simulate
+ * turning cpu_exclusive off, which will call update_cpu_domains().
+ * The lock_cpu_hotplug() call in update_cpu_domains() must not be
+ * made while holding callback_mutex.  Elsewhere the kernel nests
+ * callback_mutex inside lock_cpu_hotplug() calls.  So the reverse
+ * nesting would risk an ABBA deadlock.
+ */
+
 static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
 {
        struct cpuset *cs = dentry->d_fsdata;
@@ -1937,11 +1953,16 @@ static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry)
                mutex_unlock(&manage_mutex);
                return -EBUSY;
        }
+       if (is_cpu_exclusive(cs)) {
+               int retval = update_flag(CS_CPU_EXCLUSIVE, cs, "0");
+               if (retval < 0) {
+                       mutex_unlock(&manage_mutex);
+                       return retval;
+               }
+       }
        parent = cs->parent;
        mutex_lock(&callback_mutex);
        set_bit(CS_REMOVED, &cs->flags);
-       if (is_cpu_exclusive(cs))
-               update_cpu_domains(cs);
        list_del(&cs->sibling); /* delete my sibling from parent->children */
        spin_lock(&cs->dentry->d_lock);
        d = dget(cs->dentry);
@@ -2016,6 +2037,33 @@ out:
        return err;
 }
 
+/*
+ * The top_cpuset tracks what CPUs and Memory Nodes are online,
+ * period.  This is necessary in order to make cpusets transparent
+ * (of no affect) on systems that are actively using CPU hotplug
+ * but making no active use of cpusets.
+ *
+ * This handles CPU hotplug (cpuhp) events.  If someday Memory
+ * Nodes can be hotplugged (dynamically changing node_online_map)
+ * then we should handle that too, perhaps in a similar way.
+ */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int cpuset_handle_cpuhp(struct notifier_block *nb,
+                               unsigned long phase, void *cpu)
+{
+       mutex_lock(&manage_mutex);
+       mutex_lock(&callback_mutex);
+
+       top_cpuset.cpus_allowed = cpu_online_map;
+
+       mutex_unlock(&callback_mutex);
+       mutex_unlock(&manage_mutex);
+
+       return 0;
+}
+#endif
+
 /**
  * cpuset_init_smp - initialize cpus_allowed
  *
@@ -2026,6 +2074,8 @@ void __init cpuset_init_smp(void)
 {
        top_cpuset.cpus_allowed = cpu_online_map;
        top_cpuset.mems_allowed = node_online_map;
+
+       hotcpu_notifier(cpuset_handle_cpuhp, 0);
 }
 
 /**
@@ -2370,7 +2420,7 @@ EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
 int cpuset_excl_nodes_overlap(const struct task_struct *p)
 {
        const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */
-       int overlap = 0;                /* do cpusets overlap? */
+       int overlap = 1;                /* do cpusets overlap? */
 
        task_lock(current);
        if (current->flags & PF_EXITING) {