Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature

On Tue, Feb 28, 2017 at 10:28:20PM +0900, Byungchul Park wrote:

On Tue, Feb 28, 2017 at 02:05:13PM +0100, Peter Zijlstra wrote:

quoted

On Wed, Jan 18, 2017 at 10:17:32PM +0900, Byungchul Park wrote:

quoted

+#define MAX_XHLOCKS_NR 64UL

quoted

+#ifdef CONFIG_LOCKDEP_CROSSRELEASE
+	if (tsk->xhlocks) {
+		void *tmp = tsk->xhlocks;
+		/* Disable crossrelease for current */
+		tsk->xhlocks = NULL;
+		vfree(tmp);
+	}
+#endif

quoted

+#ifdef CONFIG_LOCKDEP_CROSSRELEASE
+	p->xhlock_idx = 0;
+	p->xhlock_idx_soft = 0;
+	p->xhlock_idx_hard = 0;
+	p->xhlock_idx_nmi = 0;
+	p->xhlocks = vzalloc(sizeof(struct hist_lock) * MAX_XHLOCKS_NR);

I don't think we need vmalloc for this now.

Really? When is a better time to do it?

I think the time creating a task is the best time to initialize it. No?

The place is fine, but I would use kmalloc() now (and subsequently kfree
on the other end) for the allocation. Its not _that_ large anymore,
right?

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