*** printk.c~	Fri Jun 30 16:24:38 2000
--- printk.c	Sun Jul  2 05:20:00 2000
***************
*** 19,32 ****
  #include <linux/smp_lock.h>
  #include <linux/console.h>
  #include <linux/init.h>
  
  #include <asm/uaccess.h>
  
  #define LOG_BUF_LEN	(16384)
  #define LOG_BUF_MASK	(LOG_BUF_LEN-1)
  
- static char buf[1024];
- 
  /* printk's without a loglevel use this.. */
  #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
  
--- 19,31 ----
  #include <linux/smp_lock.h>
  #include <linux/console.h>
  #include <linux/init.h>
+ #include <linux/slab.h>
  
  #include <asm/uaccess.h>
  
  #define LOG_BUF_LEN	(16384)
  #define LOG_BUF_MASK	(LOG_BUF_LEN-1)
  
  /* printk's without a loglevel use this.. */
  #define DEFAULT_MESSAGE_LOGLEVEL 4 /* KERN_WARNING */
  
***************
*** 253,271 ****
  
  asmlinkage int printk(const char *fmt, ...)
  {
  	va_list args;
  	int i;
  	char *msg, *p, *buf_end;
  	int line_feed;
  	static signed char msg_level = -1;
  	long flags;
  
  	va_start(args, fmt);
  	i = vsprintf(buf + 3, fmt, args); /* hopefully i < sizeof(buf)-4 */
  	buf_end = buf + 3 + i;
  	va_end(args);
! 	
  	spin_lock_irqsave(&console_lock, flags);
  	for (p = buf + 3; p < buf_end; p++) {
  		msg = p;
  		if (msg_level < 0) {
--- 252,318 ----
  
  asmlinkage int printk(const char *fmt, ...)
  {
+ 	static spinlock_t printk_buf_lock = SPIN_LOCK_UNLOCKED;
+ 	static struct task_struct *printk_buf_holder = 0;
+ 	static char printk_buf[1024];
+ 	static atomic_t lost_message = ATOMIC_INIT(0);
+ 
  	va_list args;
  	int i;
  	char *msg, *p, *buf_end;
  	int line_feed;
  	static signed char msg_level = -1;
  	long flags;
+ 	char *buf = printk_buf;
+ 
+ 	if (!spin_trylock(&printk_buf_lock)) {
+ 		/* Couldn't get spinlock... do we already have it? */
+ 		if (printk_buf_holder == current) {
+ 			/* We are already in printk... so we would be deadlocking
+ 			 * mark this as such and we'll print a message later...
+ 			 */
+ 			atomic_inc(&lost_message);
+ 			return 0;
+ 		} else {
+ 			/* Nope, wait for someone to release it... */
+ 			spin_lock(&printk_buf_lock);
+        	}
+ 	}
+ 
+ 	/* We are now the proud holders of the printk_buf_lock! :) */
+ 	printk_buf_holder = current;
+ 
+ 	if (atomic_read(&lost_message)) {
+ 		struct console *c = console_drivers;
+ 		int Count = atomic_read(&lost_message);
+ 		char dropped[] = 
+ 			"XX recursive printk's detected, message(s) lost\n";
+ 		/* Small window to lose message... not critical though */
+ 		atomic_set(&lost_message, 0);
+ 
+ 		if (Count < 100) {
+ 			if (Count > 9)
+ 				dropped[0] = (char)(Count / 10);
+ 			else
+ 				dropped[0] = ' ';
+ 
+ 			dropped[1] = Count % 10;
+ 		}
+ 
+ 		while(c) {
+ 			if ((c->flags & CON_ENABLED) && c->write)
+ 				c->write(c, dropped, 49);
+ 				c = c->next;
+ 		}
+ 	}
  
  	va_start(args, fmt);
  	i = vsprintf(buf + 3, fmt, args); /* hopefully i < sizeof(buf)-4 */
  	buf_end = buf + 3 + i;
  	va_end(args);
! 
  	spin_lock_irqsave(&console_lock, flags);
+ 	
  	for (p = buf + 3; p < buf_end; p++) {
  		msg = p;
  		if (msg_level < 0) {
***************
*** 308,315 ****
--- 355,366 ----
  		if (line_feed)
  			msg_level = -1;
  	}
+ 
  	spin_unlock_irqrestore(&console_lock, flags);
  	wake_up_interruptible(&log_wait);
+ 
+ 	spin_unlock(&printk_buf_lock);
+         
  	return i;
  }