Litmus core: per-plugin proc directories

Change the Litmus proc layout so that loaded plugins are visible in
/proc/litmus/plugins/loaded and add Litmus functions make_plugin_proc_dir()
and remove_plugin_proc_dir() to add per-plugin proc directories.

2 files changed, 75 insertions, 3 deletions

diff --git a/include/litmus/litmus.h b/include/litmus/litmus.h
index 5d20276e44f4..ccb6b137952b 100644
--- a/include/litmus/litmus.h
+++ b/include/litmus/litmus.h
@@ -9,6 +9,9 @@
 #include <linux/jiffies.h>
 #include <litmus/sched_trace.h>
 
+#include <litmus/sched_plugin.h>
+#include <linux/proc_fs.h>
+
 #ifdef CONFIG_RELEASE_MASTER
 extern atomic_t release_master_cpu;
 #endif
@@ -62,6 +65,19 @@ void exit_litmus(struct task_struct *dead_tsk);
 long litmus_admit_task(struct task_struct *tsk);
 void litmus_exit_task(struct task_struct *tsk);
 
+/*
+ * On success, returns 0 and sets the pointer to the location of the new
+ * proc dir entry, otherwise returns an error code and sets pde to NULL.
+ */
+long make_plugin_proc_dir(struct sched_plugin* plugin,
+                struct proc_dir_entry** pde);
+
+/*
+ * Plugins should deallocate all child proc directory entries before
+ * calling this, to avoid memory leaks.
+ */
+void remove_plugin_proc_dir(struct sched_plugin* plugin);
+
 #define is_realtime(t)          ((t)->policy == SCHED_LITMUS)
 #define rt_transition_pending(t) \
         ((t)->rt_param.transition_pending)
diff --git a/litmus/litmus.c b/litmus/litmus.c
index e854ba317762..3b73b39ffbbf 100644
--- a/litmus/litmus.c
+++ b/litmus/litmus.c
@@ -8,12 +8,10 @@
 #include <linux/sysrq.h>
 
 #include <linux/module.h>
-#include <linux/proc_fs.h>
 #include <linux/slab.h>
 
 #include <litmus/litmus.h>
 #include <linux/sched.h>
-#include <litmus/sched_plugin.h>
 
 #include <litmus/bheap.h>
 
@@ -687,6 +685,7 @@ static int proc_write_release_master(struct file *file,
 static struct proc_dir_entry *litmus_dir = NULL,
         *curr_file = NULL,
         *stat_file = NULL,
+        *plugs_dir = NULL,
         *plugs_file = NULL,
 #ifdef CONFIG_RELEASE_MASTER
         *release_master_file = NULL,
@@ -736,7 +735,14 @@ static int __init init_litmus_proc(void)
         stat_file = create_proc_read_entry("stats", 0444, litmus_dir,
                                            proc_read_stats, NULL);
 
-        plugs_file = create_proc_read_entry("plugins", 0444, litmus_dir,
+        plugs_dir = proc_mkdir("plugins", litmus_dir);
+        if (!plugs_dir){
+                printk(KERN_ERR "Could not allocate plugins directory "
+                                "procfs entry.\n");
+                return -ENOMEM;
+        }
+
+        plugs_file = create_proc_read_entry("loaded", 0444, plugs_dir,
                                            proc_read_plugins, NULL);
 
         return 0;
@@ -745,6 +751,8 @@ static int __init init_litmus_proc(void)
 static void exit_litmus_proc(void)
 {
         if (plugs_file)
+                remove_proc_entry("loaded", plugs_dir);
+        if (plugs_dir)
                 remove_proc_entry("plugins", litmus_dir);
         if (stat_file)
                 remove_proc_entry("stats", litmus_dir);
@@ -760,6 +768,54 @@ static void exit_litmus_proc(void)
                 remove_proc_entry("litmus", NULL);
 }
 
+long make_plugin_proc_dir(struct sched_plugin* plugin,
+                struct proc_dir_entry** pde_in)
+{
+        struct proc_dir_entry *pde_new = NULL;
+        long rv;
+
+        if (!plugin || !plugin->plugin_name){
+                printk(KERN_ERR "Invalid plugin struct passed to %s.\n",
+                                __func__);
+                rv = -EINVAL;
+                goto out_no_pde;
+        }
+
+        if (!plugs_dir){
+                printk(KERN_ERR "Could not make plugin sub-directory, because "
+                                "/proc/litmus/plugins does not exist.\n");
+                rv = -ENOENT;
+                goto out_no_pde;
+        }
+
+        pde_new = proc_mkdir(plugin->plugin_name, plugs_dir);
+        if (!pde_new){
+                printk(KERN_ERR "Could not make plugin sub-directory: "
+                                "out of memory?.\n");
+                rv = -ENOMEM;
+                goto out_no_pde;
+        }
+
+        rv = 0;
+        *pde_in = pde_new;
+        goto out_ok;
+
+out_no_pde:
+        *pde_in = NULL;
+out_ok:
+        return rv;
+}
+
+void remove_plugin_proc_dir(struct sched_plugin* plugin)
+{
+        if (!plugin || !plugin->plugin_name){
+                printk(KERN_ERR "Invalid plugin struct passed to %s.\n",
+                                __func__);
+                return;
+        }
+        remove_proc_entry(plugin->plugin_name, plugs_dir);
+}
+
 extern struct sched_plugin linux_sched_plugin;
 
 static int __init _init_litmus(void)