On Tue, 20 May 2014 19:55:45 -0700, Frank Rowand <frowand.l...@gmail.com> wrote:
> On 5/13/2014 7:58 AM, Grant Likely wrote:
> 
> > Make of_find_node_by_path() handle aliases as prefixes. To make this
> 
> > work the name search is refactored to search by path component instead
> 
> > of by full string. This should be a more efficient search, and it makes
> 
> > it possible to start a search at a subnode of a tree.
> 
> > 
> 
> > Signed-off-by: David Daney <david.da...@cavium.com>
> 
> > Signed-off-by: Pantelis Antoniou <pantelis.anton...@konsulko.com>
> 
> > [grant.likely: Rework to not require allocating at runtime]
> 
> > Acked-by: Rob Herring <r...@kernel.org>
> 
> > Signed-off-by: Grant Likely <grant.lik...@linaro.org>
> 
> > ---
> 
> >  drivers/of/base.c | 60 
> > +++++++++++++++++++++++++++++++++++++++++++++++++++----
> 
> >  1 file changed, 56 insertions(+), 4 deletions(-)
> 
> 
> 
> Was this patch created against a tree that has modifications to device tree
> 
> locking?
>   I get a hang due to deadlock when I apply it.  Patch to verify the
> cause is below.

Ummm... I may have forgotten to enable CONFIG_LOCKDEP when testing. Try
the following fix, and can you please pass me that brown paper bag.

g.

commit 35e9c5ae6c3d0b5eb91579f397d8e1ecb95ee711
Author: Grant Likely <grant.lik...@linaro.org>
Date:   Thu May 22 01:04:17 2014 +0900

    dt: Create unlocked version of for_each_child_of_node()
    
    When iterating over nodes, sometimes it needs to be done when the DT
    lock is already held. This patch makes an unlocked version of the
    for_each_child_of_node() macro.
    
    Signed-off-by: Grant Likely <grant.lik...@linaro.org>

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 8900d378c07e..c05a143b6a70 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -695,6 +695,22 @@ struct device_node *of_get_next_parent(struct device_node 
*node)
 }
 EXPORT_SYMBOL(of_get_next_parent);
 
+#define __for_each_child_of_node(parent, child) \
+       for (child = __of_get_next_child(parent, NULL); child != NULL; \
+            child = __of_get_next_child(parent, child))
+static struct device_node *__of_get_next_child(const struct device_node *node,
+                                               struct device_node *prev)
+{
+       struct device_node *next;
+
+       next = prev ? prev->sibling : node->child;
+       for (; next; next = next->sibling)
+               if (of_node_get(next))
+                       break;
+       of_node_put(prev);
+       return next;
+}
+
 /**
  *     of_get_next_child - Iterate a node childs
  *     @node:  parent node
@@ -710,11 +726,7 @@ struct device_node *of_get_next_child(const struct 
device_node *node,
        unsigned long flags;
 
        raw_spin_lock_irqsave(&devtree_lock, flags);
-       next = prev ? prev->sibling : node->child;
-       for (; next; next = next->sibling)
-               if (of_node_get(next))
-                       break;
-       of_node_put(prev);
+       next = __of_get_next_child(node, prev);
        raw_spin_unlock_irqrestore(&devtree_lock, flags);
        return next;
 }
@@ -780,7 +792,7 @@ static struct device_node *__of_find_node_by_path(struct 
device_node *parent,
        if (!len)
                return parent;
 
-       for_each_child_of_node(parent, child) {
+       __for_each_child_of_node(parent, child) {
                const char *name = strrchr(child->full_name, '/');
                if (WARN(!name, "malformed device_node %s\n", child->full_name))
                        continue;

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