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SubjectRe: spinlock assertion macros
On Thu, Jul 11, 2002 at 07:31:09AM +0200, Daniel Phillips wrote:
> I was thinking of something as simple as:
>
> #define spin_assert_locked(LOCK) BUG_ON(!spin_is_locked(LOCK))
>
> but in truth I'd be happy regardless of the internal implementation. A note
> on names: Linus likes to shout the names of his BUG macros. I've never been
> one for shouting, but it's not my kernel, and anyway, I'm happy he now likes
> asserts. I bet he'd like it more spelled like this though:
>
> MUST_HOLD(&lock);

I like lowercase better too, but you're right that Linus likes to
shout...

> And, dare I say it, what I'd *really* like to happen when the thing triggers
> is to get dropped into kdb. Ah well, perhaps in a parallel universe...

As long as you've got kdb patched in, this _should_ happen on BUG().

How about this? Are there simple *_is_locked() calls for the other
mutex mechanisms? If so, I could add those too...

Thanks,
Jesse


diff -Naur -X /home/jbarnes/dontdiff linux-2.5.25/fs/inode.c linux-2.5.25-spinassert/fs/inode.c
--- linux-2.5.25/fs/inode.c Fri Jul 5 16:42:38 2002
+++ linux-2.5.25-spinassert/fs/inode.c Thu Jul 11 10:59:23 2002
@@ -183,6 +183,8 @@
*/
void __iget(struct inode * inode)
{
+ MUST_HOLD(&inode_lock);
+
if (atomic_read(&inode->i_count)) {
atomic_inc(&inode->i_count);
return;
diff -Naur -X /home/jbarnes/dontdiff linux-2.5.25/include/linux/spinlock.h linux-2.5.25-spinassert/include/linux/spinlock.h
--- linux-2.5.25/include/linux/spinlock.h Fri Jul 5 16:42:24 2002
+++ linux-2.5.25-spinassert/include/linux/spinlock.h Thu Jul 11 11:02:17 2002
@@ -116,7 +116,19 @@
#define _raw_write_lock(lock) (void)(lock) /* Not "unused variable". */
#define _raw_write_unlock(lock) do { } while(0)

-#endif /* !SMP */
+#endif /* !CONFIG_SMP */
+
+/*
+ * Simple lock assertions for debugging and documenting where locks need
+ * to be locked/unlocked.
+ */
+#if defined(CONFIG_DEBUG_SPINLOCK) && defined(CONFIG_SMP)
+#define MUST_HOLD(lock) BUG_ON(!spin_is_locked(lock))
+#define MUST_NOT_HOLD(lock) BUG_ON(spin_is_locked(lock))
+#else
+#define MUST_HOLD(lock) do { } while(0)
+#define MUST_NOT_HOLD(lock) do { } while(0)
+#endif /* CONFIG_DEBUG_SPINLOCK && CONFIG_SMP */

#ifdef CONFIG_PREEMPT

-
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