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Message-Id: <1518416868-8804-1-git-send-email-frowand.list@gmail.com>
Date: Sun, 11 Feb 2018 22:27:48 -0800
From: frowand.list@...il.com
To: Rob Herring <robh+dt@...nel.org>, cpandya@...eaurora.org
Cc: devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] of: cache phandle nodes to reduce cost of of_find_node_by_phandle()
From: Frank Rowand <frank.rowand@...y.com>
Create a cache of the nodes that contain a phandle property. Use this
cache to find the node for a given phandle value instead of scanning
the devicetree to find the node. If the phandle value is not found
in the cache, of_find_node_by_phandle() will fall back to the tree
scan algorithm.
The cache is initialized in of_core_init().
The cache is freed via a late_initcall_sync() if modules are not
enabled.
Signed-off-by: Frank Rowand <frank.rowand@...y.com>
---
Changes since v1:
- change short description from
of: cache phandle nodes to reduce cost of of_find_node_by_phandle()
- rebase on v4.16-rc1
- reorder new functions in base.c to avoid forward declaration
- add locking around kfree(phandle_cache) for memory ordering
- add explicit check for non-null of phandle_cache in
of_find_node_by_phandle(). There is already a check for !handle,
which prevents accessing a null phandle_cache, but that dependency
is not obvious, so this check makes it more apparent.
- do not free phandle_cache if modules are enabled, so that
cached phandles will be available when modules are loaded
drivers/of/base.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++---
drivers/of/of_private.h | 5 +++
drivers/of/resolver.c | 21 -----------
3 files changed, 94 insertions(+), 25 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ad28de96e13f..b3597c250837 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -91,10 +91,88 @@ int __weak of_node_to_nid(struct device_node *np)
}
#endif
+static struct device_node **phandle_cache;
+static u32 max_phandle_cache;
+
+phandle live_tree_max_phandle(void)
+{
+ struct device_node *node;
+ phandle max_phandle;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+
+ max_phandle = 0;
+ for_each_of_allnodes(node) {
+ if (node->phandle != OF_PHANDLE_ILLEGAL &&
+ node->phandle > max_phandle)
+ max_phandle = node->phandle;
+ }
+
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+
+ return max_phandle;
+}
+
+static void of_populate_phandle_cache(void)
+{
+ unsigned long flags;
+ phandle max_phandle;
+ u32 nodes = 0;
+ struct device_node *np;
+
+ if (phandle_cache)
+ return;
+
+ max_phandle = live_tree_max_phandle();
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+
+ for_each_of_allnodes(np)
+ nodes++;
+
+ /* sanity cap for malformed tree */
+ if (max_phandle > nodes)
+ max_phandle = nodes;
+
+ phandle_cache = kzalloc((max_phandle + 1) * sizeof(*phandle_cache),
+ GFP_ATOMIC);
+
+ for_each_of_allnodes(np)
+ if (np->phandle != OF_PHANDLE_ILLEGAL &&
+ np->phandle <= max_phandle &&
+ np->phandle)
+ phandle_cache[np->phandle] = np;
+
+ max_phandle_cache = max_phandle;
+
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+}
+
+#ifndef CONFIG_MODULES
+static int __init of_free_phandle_cache(void)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&devtree_lock, flags);
+
+ max_phandle_cache = 0;
+ kfree(phandle_cache);
+ phandle_cache = NULL;
+
+ raw_spin_unlock_irqrestore(&devtree_lock, flags);
+
+ return 0;
+}
+late_initcall_sync(of_free_phandle_cache);
+#endif
+
void __init of_core_init(void)
{
struct device_node *np;
+ of_populate_phandle_cache();
+
/* Create the kset, and register existing nodes */
mutex_lock(&of_mutex);
of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj);
@@ -1021,16 +1099,23 @@ int of_modalias_node(struct device_node *node, char *modalias, int len)
*/
struct device_node *of_find_node_by_phandle(phandle handle)
{
- struct device_node *np;
+ struct device_node *np = NULL;
unsigned long flags;
if (!handle)
return NULL;
raw_spin_lock_irqsave(&devtree_lock, flags);
- for_each_of_allnodes(np)
- if (np->phandle == handle)
- break;
+
+ if (phandle_cache && handle <= max_phandle_cache)
+ np = phandle_cache[handle];
+
+ if (!np || np->phandle != handle) {
+ for_each_of_allnodes(np)
+ if (np->phandle == handle)
+ break;
+ }
+
of_node_get(np);
raw_spin_unlock_irqrestore(&devtree_lock, flags);
return np;
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index 0c609e7d0334..18e03c9d4b55 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -131,6 +131,11 @@ extern void __of_update_property_sysfs(struct device_node *np,
extern void __of_sysfs_remove_bin_file(struct device_node *np,
struct property *prop);
+/* illegal phandle value (set when unresolved) */
+#define OF_PHANDLE_ILLEGAL 0xdeadbeef
+
+extern phandle live_tree_max_phandle(void);
+
/* iterators for transactions, used for overlays */
/* forward iterator */
#define for_each_transaction_entry(_oft, _te) \
diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
index 740d19bde601..a7580c24737a 100644
--- a/drivers/of/resolver.c
+++ b/drivers/of/resolver.c
@@ -19,27 +19,6 @@
#include "of_private.h"
-/* illegal phandle value (set when unresolved) */
-#define OF_PHANDLE_ILLEGAL 0xdeadbeef
-
-static phandle live_tree_max_phandle(void)
-{
- struct device_node *node;
- phandle phandle;
- unsigned long flags;
-
- raw_spin_lock_irqsave(&devtree_lock, flags);
- phandle = 0;
- for_each_of_allnodes(node) {
- if (node->phandle != OF_PHANDLE_ILLEGAL &&
- node->phandle > phandle)
- phandle = node->phandle;
- }
- raw_spin_unlock_irqrestore(&devtree_lock, flags);
-
- return phandle;
-}
-
static void adjust_overlay_phandles(struct device_node *overlay,
int phandle_delta)
{
--
Frank Rowand <frank.rowand@...y.com>
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