Messages in this thread Patch in this message | | | Date | Tue, 20 May 2014 19:55:45 -0700 | From | Frank Rowand <> | Subject | Re: [PATCH 2/3] of: Make of_find_node_by_path() handle /aliases |
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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.daney@cavium.com>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> [grant.likely: Rework to not require allocating at runtime]
> Acked-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Grant Likely <grant.likely@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.
From: Frank Rowand <frank.rowand@sonymobile.com>
Do not apply this patch -- it is not a valid fix. The point of this patch is to confirm the cause of a bug.
Problem seen on 3.15-rc1 with dragonboard platform patches added.
The dragonboard hangs on boot the very first time that of_find_node_by_path() is called:
of_find_node_by_path() raw_spin_lock_irqsave(&devtree_lock, flags) np = __of_find_node_by_path(np, path) for_each_child_of_node(parent, child) {
// This is a define: #define for_each_child_of_node(parent, child) \ for (child = of_get_next_child(parent, NULL); child != NULL; \
// Resulting in a deadlock when of_get_next_child() // attempts to lock the same lock: raw_spin_lock_irqsave(&devtree_lock, flags)
When this patch is applied, the first lock is commented out so the deadlock does not occur and the boot completes.
Not-signed-off-by: Frank Rowand <frank.rowand@sonymobile.com> --- drivers/of/base.c | 4 ++++ 1 file changed, 4 insertions(+)
Index: b/drivers/of/base.c =================================================================== --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -835,13 +835,17 @@ struct device_node *of_find_node_by_path } /* Step down the tree matching path components */ +#if 0 raw_spin_lock_irqsave(&devtree_lock, flags); +#endif while (np && *path == '/') { path++; /* Increment past '/' delimiter */ np = __of_find_node_by_path(np, path); path = strchrnul(path, '/'); } +#if 0 raw_spin_unlock_irqrestore(&devtree_lock, flags); +#endif return np; } EXPORT_SYMBOL(of_find_node_by_path);
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