1 files changed, 79 insertions, 3 deletions

diff --git a/litmus/litmus.c b/litmus/litmus.c
index 3cf7cb9e8a9f..e43596a5104c 100644
--- a/litmus/litmus.c
+++ b/litmus/litmus.c
@@ -24,6 +24,8 @@
 /* Number of RT tasks that exist in the system */
 atomic_t rt_task_count          = ATOMIC_INIT(0);
 static DEFINE_SPINLOCK(task_transition_lock);
+/* synchronize plugin switching */
+atomic_t cannot_use_plugin      = ATOMIC_INIT(0);
 
 /* Give log messages sequential IDs. */
 atomic_t __log_seq_no = ATOMIC_INIT(0);
@@ -369,13 +371,17 @@ void litmus_exit_task(struct task_struct* tsk)
         }
 }
 
+/* IPI callback to synchronize plugin switching */
+static void synch_on_plugin_switch(void* info)
+{
+        while (atomic_read(&cannot_use_plugin))
+                cpu_relax();
+}
+
 /* Switching a plugin in use is tricky.
  * We must watch out that no real-time tasks exists
  * (and that none is created in parallel) and that the plugin is not
  * currently in use on any processor (in theory).
- *
- * For now, we don't enforce the second part since it is unlikely to cause
- * any trouble by itself as long as we don't unload modules.
  */
 int switch_sched_plugin(struct sched_plugin* plugin)
 {
@@ -384,6 +390,11 @@ int switch_sched_plugin(struct sched_plugin* plugin)
 
         BUG_ON(!plugin);
 
+        /* forbid other cpus to use the plugin */
+        atomic_set(&cannot_use_plugin, 1);
+        /* send IPI to force other CPUs to synch with us */
+        smp_call_function(synch_on_plugin_switch, NULL, 0);
+
         /* stop task transitions */
         spin_lock_irqsave(&task_transition_lock, flags);
 
@@ -404,6 +415,7 @@ int switch_sched_plugin(struct sched_plugin* plugin)
                 ret = -EBUSY;
 out:
         spin_unlock_irqrestore(&task_transition_lock, flags);
+        atomic_set(&cannot_use_plugin, 0);
         return ret;
 }
 
@@ -554,6 +566,55 @@ static int proc_write_curr(struct file *file,
         return len;
 }
 
+static int proc_read_cluster_size(char *page, char **start,
+                          off_t off, int count,
+                          int *eof, void *data)
+{
+        int len;
+        if (cluster_cache_index == 2)
+                len = snprintf(page, PAGE_SIZE, "L2\n");
+        else if (cluster_cache_index == 3)
+                len = snprintf(page, PAGE_SIZE, "L3\n");
+        else /* (cluster_cache_index == 1) */
+                len = snprintf(page, PAGE_SIZE, "L1\n");
+
+        return len;
+}
+
+static int proc_write_cluster_size(struct file *file,
+                           const char *buffer,
+                           unsigned long count,
+                           void *data)
+{
+        int len;
+        /* L2, L3 */
+        char cache_name[33];
+
+        if(count > 32)
+                len = 32;
+        else
+                len = count;
+
+        if(copy_from_user(cache_name, buffer, len))
+                return -EFAULT;
+
+        cache_name[len] = '\0';
+        /* chomp name */
+        if (len > 1 && cache_name[len - 1] == '\n')
+                cache_name[len - 1] = '\0';
+
+        /* do a quick and dirty comparison to find the cluster size */
+        if (!strcmp(cache_name, "L2"))
+                cluster_cache_index = 2;
+        else if (!strcmp(cache_name, "L3"))
+                cluster_cache_index = 3;
+        else if (!strcmp(cache_name, "L1"))
+                cluster_cache_index = 1;
+        else
+                printk(KERN_INFO "Cluster '%s' is unknown.\n", cache_name);
+
+        return len;
+}
 
 static int proc_read_release_master(char *page, char **start,
                                     off_t off, int count,
@@ -609,6 +670,7 @@ static struct proc_dir_entry *litmus_dir = NULL,
         *curr_file = NULL,
         *stat_file = NULL,
         *plugs_file = NULL,
+        *clus_cache_idx_file = NULL,
         *release_master_file = NULL;
 
 static int __init init_litmus_proc(void)
@@ -639,6 +701,16 @@ static int __init init_litmus_proc(void)
         release_master_file->read_proc = proc_read_release_master;
         release_master_file->write_proc  = proc_write_release_master;
 
+        clus_cache_idx_file = create_proc_entry("cluster_cache",
+                                                0644, litmus_dir);
+        if (!clus_cache_idx_file) {
+                printk(KERN_ERR "Could not allocate cluster_cache "
+                       "procfs entry.\n");
+                return -ENOMEM;
+        }
+        clus_cache_idx_file->read_proc = proc_read_cluster_size;
+        clus_cache_idx_file->write_proc = proc_write_cluster_size;
+
         stat_file = create_proc_read_entry("stats", 0444, litmus_dir,
                                            proc_read_stats, NULL);
 
@@ -656,6 +728,10 @@ static void exit_litmus_proc(void)
                 remove_proc_entry("stats", litmus_dir);
         if (curr_file)
                 remove_proc_entry("active_plugin", litmus_dir);
+        if (clus_cache_idx_file)
+                remove_proc_entry("cluster_cache", litmus_dir);
+        if (release_master_file)
+                remove_proc_entry("release_master", litmus_dir);
         if (litmus_dir)
                 remove_proc_entry("litmus", NULL);
 }