1 files changed, 174 insertions, 0 deletions

diff --git a/kernel/rcu/tiny_plugin.h b/kernel/rcu/tiny_plugin.h
new file mode 100644
index 000000000000..280d06cae352
--- /dev/null
+++ b/kernel/rcu/tiny_plugin.h
@@ -0,0 +1,174 @@
+/*
+ * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition
+ * Internal non-public definitions that provide either classic
+ * or preemptible semantics.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (c) 2010 Linaro
+ *
+ * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+ */
+
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+/* Global control variables for rcupdate callback mechanism. */
+struct rcu_ctrlblk {
+        struct rcu_head *rcucblist;     /* List of pending callbacks (CBs). */
+        struct rcu_head **donetail;     /* ->next pointer of last "done" CB. */
+        struct rcu_head **curtail;      /* ->next pointer of last CB. */
+        RCU_TRACE(long qlen);           /* Number of pending CBs. */
+        RCU_TRACE(unsigned long gp_start); /* Start time for stalls. */
+        RCU_TRACE(unsigned long ticks_this_gp); /* Statistic for stalls. */
+        RCU_TRACE(unsigned long jiffies_stall); /* Jiffies at next stall. */
+        RCU_TRACE(const char *name);    /* Name of RCU type. */
+};
+
+/* Definition for rcupdate control block. */
+static struct rcu_ctrlblk rcu_sched_ctrlblk = {
+        .donetail       = &rcu_sched_ctrlblk.rcucblist,
+        .curtail        = &rcu_sched_ctrlblk.rcucblist,
+        RCU_TRACE(.name = "rcu_sched")
+};
+
+static struct rcu_ctrlblk rcu_bh_ctrlblk = {
+        .donetail       = &rcu_bh_ctrlblk.rcucblist,
+        .curtail        = &rcu_bh_ctrlblk.rcucblist,
+        RCU_TRACE(.name = "rcu_bh")
+};
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#include <linux/kernel_stat.h>
+
+int rcu_scheduler_active __read_mostly;
+EXPORT_SYMBOL_GPL(rcu_scheduler_active);
+
+/*
+ * During boot, we forgive RCU lockdep issues.  After this function is
+ * invoked, we start taking RCU lockdep issues seriously.
+ */
+void __init rcu_scheduler_starting(void)
+{
+        WARN_ON(nr_context_switches() > 0);
+        rcu_scheduler_active = 1;
+}
+
+#endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
+
+#ifdef CONFIG_RCU_TRACE
+
+static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n)
+{
+        unsigned long flags;
+
+        local_irq_save(flags);
+        rcp->qlen -= n;
+        local_irq_restore(flags);
+}
+
+/*
+ * Dump statistics for TINY_RCU, such as they are.
+ */
+static int show_tiny_stats(struct seq_file *m, void *unused)
+{
+        seq_printf(m, "rcu_sched: qlen: %ld\n", rcu_sched_ctrlblk.qlen);
+        seq_printf(m, "rcu_bh: qlen: %ld\n", rcu_bh_ctrlblk.qlen);
+        return 0;
+}
+
+static int show_tiny_stats_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, show_tiny_stats, NULL);
+}
+
+static const struct file_operations show_tiny_stats_fops = {
+        .owner = THIS_MODULE,
+        .open = show_tiny_stats_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = single_release,
+};
+
+static struct dentry *rcudir;
+
+static int __init rcutiny_trace_init(void)
+{
+        struct dentry *retval;
+
+        rcudir = debugfs_create_dir("rcu", NULL);
+        if (!rcudir)
+                goto free_out;
+        retval = debugfs_create_file("rcudata", 0444, rcudir,
+                                     NULL, &show_tiny_stats_fops);
+        if (!retval)
+                goto free_out;
+        return 0;
+free_out:
+        debugfs_remove_recursive(rcudir);
+        return 1;
+}
+
+static void __exit rcutiny_trace_cleanup(void)
+{
+        debugfs_remove_recursive(rcudir);
+}
+
+module_init(rcutiny_trace_init);
+module_exit(rcutiny_trace_cleanup);
+
+MODULE_AUTHOR("Paul E. McKenney");
+MODULE_DESCRIPTION("Read-Copy Update tracing for tiny implementation");
+MODULE_LICENSE("GPL");
+
+static void check_cpu_stall(struct rcu_ctrlblk *rcp)
+{
+        unsigned long j;
+        unsigned long js;
+
+        if (rcu_cpu_stall_suppress)
+                return;
+        rcp->ticks_this_gp++;
+        j = jiffies;
+        js = rcp->jiffies_stall;
+        if (*rcp->curtail && ULONG_CMP_GE(j, js)) {
+                pr_err("INFO: %s stall on CPU (%lu ticks this GP) idle=%llx (t=%lu jiffies q=%ld)\n",
+                       rcp->name, rcp->ticks_this_gp, rcu_dynticks_nesting,
+                       jiffies - rcp->gp_start, rcp->qlen);
+                dump_stack();
+        }
+        if (*rcp->curtail && ULONG_CMP_GE(j, js))
+                rcp->jiffies_stall = jiffies +
+                        3 * rcu_jiffies_till_stall_check() + 3;
+        else if (ULONG_CMP_GE(j, js))
+                rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
+}
+
+static void reset_cpu_stall_ticks(struct rcu_ctrlblk *rcp)
+{
+        rcp->ticks_this_gp = 0;
+        rcp->gp_start = jiffies;
+        rcp->jiffies_stall = jiffies + rcu_jiffies_till_stall_check();
+}
+
+static void check_cpu_stalls(void)
+{
+        RCU_TRACE(check_cpu_stall(&rcu_bh_ctrlblk));
+        RCU_TRACE(check_cpu_stall(&rcu_sched_ctrlblk));
+}
+
+#endif /* #ifdef CONFIG_RCU_TRACE */