From fbdb49ffdcff694972edebb91fd5bac19810a193 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@nicira.com>
Date: Mon, 21 Jul 2008 13:39:26 -0700
Subject: [PATCH] Verify that sleeping is allowed in chain contexts where
 Broadcom will need to.

---
 datapath/chain.c                              |  3 +++
 .../compat-2.4/include/linux/kernel.h         | 23 +++++++++++++++++++
 datapath/linux-2.4/compat-2.4/kernel.c        | 19 +++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/datapath/chain.c b/datapath/chain.c
index f7ea1dc6..71e00ee6 100644
--- a/datapath/chain.c
+++ b/datapath/chain.c
@@ -89,6 +89,7 @@ int chain_insert(struct sw_chain *chain, struct sw_flow *flow)
 {
 	int i;
 
+	might_sleep();
 	for (i = 0; i < chain->n_tables; i++) {
 		struct sw_table *t = chain->tables[i];
 		if (t->insert(t, flow))
@@ -112,6 +113,7 @@ int chain_delete(struct sw_chain *chain, const struct sw_flow_key *key,
 	int count = 0;
 	int i;
 
+	might_sleep();
 	for (i = 0; i < chain->n_tables; i++) {
 		struct sw_table *t = chain->tables[i];
 		count += t->delete(t, key, priority, strict);
@@ -133,6 +135,7 @@ int chain_timeout(struct sw_chain *chain)
 	int count = 0;
 	int i;
 
+	might_sleep();
 	for (i = 0; i < chain->n_tables; i++) {
 		struct sw_table *t = chain->tables[i];
 		count += t->timeout(chain->dp, t);
diff --git a/datapath/linux-2.4/compat-2.4/include/linux/kernel.h b/datapath/linux-2.4/compat-2.4/include/linux/kernel.h
index 329dab53..543ba9b6 100644
--- a/datapath/linux-2.4/compat-2.4/include/linux/kernel.h
+++ b/datapath/linux-2.4/compat-2.4/include/linux/kernel.h
@@ -2,6 +2,7 @@
 #define __LINUX_KERNEL_WRAPPER_H 1
 
 #include_next <linux/kernel.h>
+#include <linux/config.h>
 
 /**
  * container_of - cast a member of a structure out to the containing structure
@@ -40,4 +41,26 @@ int vprintk(const char *msg, ...)
 /* Force a compilation error if condition is true */
 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 
+/**
+ * might_sleep - annotation for functions that can sleep
+ *
+ * this macro will print a stack trace if it is executed in an atomic
+ * context (spinlock, irq-handler, ...).
+ *
+ * This is a useful debugging help to be able to catch problems early and not
+ * be bitten later when the calling function happens to sleep when it is not
+ * supposed to.
+ */
+#define might_resched() do { } while (0)
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+  void __might_sleep(char *file, int line);
+# define might_sleep() \
+	do { __might_sleep(__FILE__, __LINE__); might_resched(); } while (0)
+#else
+# define might_sleep() do { might_resched(); } while (0)
+#endif
+
+#define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
+
 #endif
diff --git a/datapath/linux-2.4/compat-2.4/kernel.c b/datapath/linux-2.4/compat-2.4/kernel.c
index a08bb2d8..36d2d8ae 100644
--- a/datapath/linux-2.4/compat-2.4/kernel.c
+++ b/datapath/linux-2.4/compat-2.4/kernel.c
@@ -2,9 +2,11 @@
  * Distributed under the terms of the GNU GPL version 2.
  */
 
+#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <asm/hardirq.h>
 
 int vprintk(const char *msg, ...)
 {
@@ -25,3 +27,20 @@ int vprintk(const char *msg, ...)
 }
 
 EXPORT_SYMBOL(vprintk);
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+void __might_sleep(char *file, int line)
+{
+	static unsigned long prev_jiffy;	/* ratelimiting */
+
+	if ((in_interrupt()) && !oops_in_progress) {
+		if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
+			return;
+		prev_jiffy = jiffies;
+		printk(KERN_ERR "BUG: sleeping function called from invalid"
+				" context at %s:%d\n", file, line);
+		dump_stack();
+	}
+}
+EXPORT_SYMBOL(__might_sleep);
+#endif
-- 
2.30.2