Add LITMUS^RT core implementation

This patch adds the core of LITMUS^RT:

 - library functionality (heaps, rt_domain, prioritization, etc.)
 - budget enforcement logic
 - job management
 - system call backends
 - virtual devices (control page, etc.)
 - scheduler plugin API (and dummy plugin)

This code compiles, but is not yet integrated with the rest of Linux.

1 files changed, 407 insertions, 0 deletions

diff --git a/litmus/litmus_proc.c b/litmus/litmus_proc.c
new file mode 100644
index 000000000000..1ebf1277f5d3
--- /dev/null
+++ b/litmus/litmus_proc.c
@@ -0,0 +1,407 @@
+/*
+ * litmus_proc.c -- Implementation of the /proc/litmus directory tree.
+ */
+
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+
+#include <litmus/litmus.h>
+#include <litmus/litmus_proc.h>
+
+#include <litmus/clustered.h>
+
+/* in litmus/litmus.c */
+extern atomic_t rt_task_count;
+
+static struct proc_dir_entry *litmus_dir = NULL,
+        *curr_file = NULL,
+        *stat_file = NULL,
+        *plugs_dir = NULL,
+#ifdef CONFIG_RELEASE_MASTER
+        *release_master_file = NULL,
+#endif
+        *plugs_file = NULL;
+
+/* in litmus/sync.c */
+int count_tasks_waiting_for_release(void);
+
+static int litmus_stats_proc_show(struct seq_file *m, void *v)
+{
+        seq_printf(m,
+                   "real-time tasks   = %d\n"
+                   "ready for release = %d\n",
+                   atomic_read(&rt_task_count),
+                   count_tasks_waiting_for_release());
+        return 0;
+}
+
+static int litmus_stats_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, litmus_stats_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations litmus_stats_proc_fops = {
+        .open           = litmus_stats_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+
+static int litmus_loaded_proc_show(struct seq_file *m, void *v)
+{
+        print_sched_plugins(m);
+        return 0;
+}
+
+static int litmus_loaded_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, litmus_loaded_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations litmus_loaded_proc_fops = {
+        .open           = litmus_loaded_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+
+
+
+/* in litmus/litmus.c */
+int switch_sched_plugin(struct sched_plugin*);
+
+static ssize_t litmus_active_proc_write(struct file *file,
+                                        const char __user *buffer, size_t count,
+                                        loff_t *ppos)
+{
+        char name[65];
+        struct sched_plugin* found;
+        ssize_t ret = -EINVAL;
+        int err;
+
+
+        ret = copy_and_chomp(name, sizeof(name), buffer, count);
+        if (ret < 0)
+                return ret;
+
+        found = find_sched_plugin(name);
+
+        if (found) {
+                err = switch_sched_plugin(found);
+                if (err) {
+                        printk(KERN_INFO "Could not switch plugin: %d\n", err);
+                        ret = err;
+                }
+        } else {
+                printk(KERN_INFO "Plugin '%s' is unknown.\n", name);
+                ret = -ESRCH;
+        }
+
+        return ret;
+}
+
+static int litmus_active_proc_show(struct seq_file *m, void *v)
+{
+        seq_printf(m, "%s\n", litmus->plugin_name);
+        return 0;
+}
+
+static int litmus_active_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, litmus_active_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations litmus_active_proc_fops = {
+        .open           = litmus_active_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = litmus_active_proc_write,
+};
+
+
+#ifdef CONFIG_RELEASE_MASTER
+static ssize_t litmus_release_master_proc_write(
+        struct file *file,
+        const char __user *buffer, size_t count,
+        loff_t *ppos)
+{
+        int cpu, err, online = 0;
+        char msg[64];
+        ssize_t len;
+
+        len = copy_and_chomp(msg, sizeof(msg), buffer, count);
+
+        if (len < 0)
+                return len;
+
+        if (strcmp(msg, "NO_CPU") == 0)
+                atomic_set(&release_master_cpu, NO_CPU);
+        else {
+                err = sscanf(msg, "%d", &cpu);
+                if (err == 1 && cpu >= 0 && (online = cpu_online(cpu))) {
+                        atomic_set(&release_master_cpu, cpu);
+                } else {
+                        TRACE("invalid release master: '%s' "
+                              "(err:%d cpu:%d online:%d)\n",
+                              msg, err, cpu, online);
+                        len = -EINVAL;
+                }
+        }
+        return len;
+}
+
+static int litmus_release_master_proc_show(struct seq_file *m, void *v)
+{
+        int master;
+        master = atomic_read(&release_master_cpu);
+        if (master == NO_CPU)
+                seq_printf(m, "NO_CPU\n");
+        else
+                seq_printf(m, "%d\n", master);
+        return 0;
+}
+
+static int litmus_release_master_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, litmus_release_master_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations litmus_release_master_proc_fops = {
+        .open           = litmus_release_master_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = litmus_release_master_proc_write,
+};
+#endif
+
+int __init init_litmus_proc(void)
+{
+        litmus_dir = proc_mkdir("litmus", NULL);
+        if (!litmus_dir) {
+                printk(KERN_ERR "Could not allocate LITMUS^RT procfs entry.\n");
+                return -ENOMEM;
+        }
+
+        curr_file = proc_create("active_plugin", 0644, litmus_dir,
+                                &litmus_active_proc_fops);
+
+        if (!curr_file) {
+                printk(KERN_ERR "Could not allocate active_plugin "
+                       "procfs entry.\n");
+                return -ENOMEM;
+        }
+
+#ifdef CONFIG_RELEASE_MASTER
+        release_master_file = proc_create("release_master", 0644, litmus_dir,
+                                          &litmus_release_master_proc_fops);
+        if (!release_master_file) {
+                printk(KERN_ERR "Could not allocate release_master "
+                       "procfs entry.\n");
+                return -ENOMEM;
+        }
+#endif
+
+        stat_file = proc_create("stats", 0444, litmus_dir, &litmus_stats_proc_fops);
+
+        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 = proc_create("loaded", 0444, plugs_dir,
+                                 &litmus_loaded_proc_fops);
+
+        return 0;
+}
+
+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);
+        if (curr_file)
+                remove_proc_entry("active_plugin", litmus_dir);
+#ifdef CONFIG_RELEASE_MASTER
+        if (release_master_file)
+                remove_proc_entry("release_master", litmus_dir);
+#endif
+        if (litmus_dir)
+                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);
+}
+
+
+
+/* misc. I/O helper functions */
+
+int copy_and_chomp(char *kbuf, unsigned long ksize,
+                   __user const char* ubuf, unsigned long ulength)
+{
+        /* caller must provide buffer space */
+        BUG_ON(!ksize);
+
+        ksize--; /* leave space for null byte */
+
+        if (ksize > ulength)
+                ksize = ulength;
+
+        if(copy_from_user(kbuf, ubuf, ksize))
+                return -EFAULT;
+
+        kbuf[ksize] = '\0';
+
+        /* chomp kbuf */
+        if (ksize > 0 && kbuf[ksize - 1] == '\n')
+                kbuf[ksize - 1] = '\0';
+
+        return ksize;
+}
+
+/* helper functions for clustered plugins */
+static const char* cache_level_names[] = {
+        "ALL",
+        "L1",
+        "L2",
+        "L3",
+};
+
+int parse_cache_level(const char *cache_name, enum cache_level *level)
+{
+        int err = -EINVAL;
+        int i;
+        /* do a quick and dirty comparison to find the cluster size */
+        for (i = GLOBAL_CLUSTER; i <= L3_CLUSTER; i++)
+                if (!strcmp(cache_name, cache_level_names[i])) {
+                        *level = (enum cache_level) i;
+                        err = 0;
+                        break;
+                }
+        return err;
+}
+
+const char* cache_level_name(enum cache_level level)
+{
+        int idx = level;
+
+        if (idx >= GLOBAL_CLUSTER && idx <= L3_CLUSTER)
+                return cache_level_names[idx];
+        else
+                return "INVALID";
+}
+
+
+
+
+/* proc file interface to configure the cluster size */
+
+static ssize_t litmus_cluster_proc_write(struct file *file,
+                                        const char __user *buffer, size_t count,
+                                        loff_t *ppos)
+{
+        enum cache_level *level = (enum cache_level *) PDE_DATA(file_inode(file));
+        ssize_t len;
+        char cache_name[8];
+
+        len = copy_and_chomp(cache_name, sizeof(cache_name), buffer, count);
+
+        if (len > 0 && parse_cache_level(cache_name, level)) {
+                printk(KERN_INFO "Cluster '%s' is unknown.\n", cache_name);
+                len = -EINVAL;
+        }
+
+        return len;
+}
+
+static int litmus_cluster_proc_show(struct seq_file *m, void *v)
+{
+        enum cache_level *level = (enum cache_level *)  m->private;
+
+        seq_printf(m, "%s\n", cache_level_name(*level));
+        return 0;
+}
+
+static int litmus_cluster_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, litmus_cluster_proc_show, PDE_DATA(inode));
+}
+
+static const struct file_operations litmus_cluster_proc_fops = {
+        .open           = litmus_cluster_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = litmus_cluster_proc_write,
+};
+
+struct proc_dir_entry* create_cluster_file(struct proc_dir_entry* parent,
+                                           enum cache_level* level)
+{
+        struct proc_dir_entry* cluster_file;
+
+
+        cluster_file = proc_create_data("cluster", 0644, parent,
+                                        &litmus_cluster_proc_fops,
+                                        (void *) level);
+        if (!cluster_file) {
+                printk(KERN_ERR
+                       "Could not cluster procfs entry.\n");
+        }
+        return cluster_file;
+}