xv6

commit 645f9acbb0c5965e38e9e77d4387ec8bcbb40f70
parent 8a88776ba9dffa2d513f0ba2061b701284aea9c9
Author: Brian Swetland <swetland@frotz.net>
Date:   Thu,  2 Jan 2014 14:03:22 -0800

spinlock: print backtrace when panic'ing on double-acquire

This way you get the backtrace of where the lock was first acquired
in addtion to the backtrace of this call to acquire().

Diffstat:
M
kernel/spinlock.c
 | 
8
+++++++-

1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
@@ -25,8 +25,14 @@ void
 acquire(struct spinlock *lk)
 {
   pushcli(); // disable interrupts to avoid deadlock.
-  if(holding(lk))
+  if(holding(lk)) {
+    int i;
+    cprintf("lock '%s':\n", lk->name);
+    for (i = 0; i < 10; i++)
+      cprintf(" %p", lk->pcs[i]);
+    cprintf("\n");
     panic("acquire");
+  }
 
   // The xchg is atomic.
   // It also serializes, so that reads after acquire are not