[Prism54-devel] sleep_on() considered harmful.

[David Woodhouse]

On Thu, 2004-01-22 at 22:02 -0500, Luis R. Rodriguez wrote:
> Commited, thanks

This 2.6 patch is what prompted it, btw...

===== include/linux/smp_lock.h 1.7 vs edited =====
--- 1.7/include/linux/smp_lock.h	Mon Jan 19 23:38:11 2004
+++ edited/include/linux/smp_lock.h	Thu Jan 22 09:15:17 2004
@@ -5,7 +5,9 @@
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 
-#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
+#define BKL_DEBUG /* For testing for sleep_on() abuse */
+
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) || defined(BKL_DEBUG)
 
 extern spinlock_t kernel_flag;
 
===== kernel/sched.c 1.236 vs edited =====
--- 1.236/kernel/sched.c	Mon Jan 19 23:38:12 2004
+++ edited/kernel/sched.c	Thu Jan 22 10:49:55 2004
@@ -1903,10 +1903,21 @@
 	__remove_wait_queue(q, &wait);			\
 	spin_unlock_irqrestore(&q->lock, flags);
 
+#define SLEEP_ON_BKLCHECK				\
+	if (unlikely(!kernel_locked()) &&		\
+	    sleep_on_bkl_warnings < 10) {		\
+		sleep_on_bkl_warnings++;		\
+		WARN_ON(1);				\
+	}
+
+static int sleep_on_bkl_warnings;
+
 void interruptible_sleep_on(wait_queue_head_t *q)
 {
 	SLEEP_ON_VAR
 
+	SLEEP_ON_BKLCHECK
+
 	current->state = TASK_INTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
@@ -1920,6 +1931,8 @@
 {
 	SLEEP_ON_VAR
 
+	SLEEP_ON_BKLCHECK
+
 	current->state = TASK_INTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
@@ -1935,6 +1948,8 @@
 {
 	SLEEP_ON_VAR
 
+	SLEEP_ON_BKLCHECK
+
 	current->state = TASK_UNINTERRUPTIBLE;
 
 	SLEEP_ON_HEAD
@@ -1947,6 +1962,8 @@
 long sleep_on_timeout(wait_queue_head_t *q, long timeout)
 {
 	SLEEP_ON_VAR
+
+	SLEEP_ON_BKLCHECK
 
 	current->state = TASK_UNINTERRUPTIBLE;
 

-- 
dwmw2