[PATCH 4.17 268/324] of: overlay: update phandle cache on overlay apply and remove

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Frank Rowand <frank.rowand@xxxxxxxx>

[ Upstream commit b9952b5218added5577e4a3443969bc20884cea9 ]

A comment in the review of the patch adding the phandle cache said that
the cache would have to be updated when modules are applied and removed.
This patch implements the cache updates.

Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
Reported-by: Alan Tull <atull@xxxxxxxxxx>
Suggested-by: Alan Tull <atull@xxxxxxxxxx>
Signed-off-by: Frank Rowand <frank.rowand@xxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/of/base.c       |    6 +++---
 drivers/of/of_private.h |    2 ++
 drivers/of/overlay.c    |   11 +++++++++++
 3 files changed, 16 insertions(+), 3 deletions(-)

--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -102,7 +102,7 @@ static u32 phandle_cache_mask;
  *   - the phandle lookup overhead reduction provided by the cache
  *     will likely be less
  */
-static void of_populate_phandle_cache(void)
+void of_populate_phandle_cache(void)
 {
 	unsigned long flags;
 	u32 cache_entries;
@@ -134,8 +134,7 @@ out:
 	raw_spin_unlock_irqrestore(&devtree_lock, flags);
 }
 
-#ifndef CONFIG_MODULES
-static int __init of_free_phandle_cache(void)
+int of_free_phandle_cache(void)
 {
 	unsigned long flags;
 
@@ -148,6 +147,7 @@ static int __init of_free_phandle_cache(
 
 	return 0;
 }
+#if !defined(CONFIG_MODULES)
 late_initcall_sync(of_free_phandle_cache);
 #endif
 
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -79,6 +79,8 @@ int of_resolve_phandles(struct device_no
 #if defined(CONFIG_OF_OVERLAY)
 void of_overlay_mutex_lock(void);
 void of_overlay_mutex_unlock(void);
+int of_free_phandle_cache(void);
+void of_populate_phandle_cache(void);
 #else
 static inline void of_overlay_mutex_lock(void) {};
 static inline void of_overlay_mutex_unlock(void) {};
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -804,6 +804,8 @@ static int of_overlay_apply(const void *
 		goto err_free_overlay_changeset;
 	}
 
+	of_populate_phandle_cache();
+
 	ret = __of_changeset_apply_notify(&ovcs->cset);
 	if (ret)
 		pr_err("overlay changeset entry notify error %d\n", ret);
@@ -1046,8 +1048,17 @@ int of_overlay_remove(int *ovcs_id)
 
 	list_del(&ovcs->ovcs_list);
 
+	/*
+	 * Disable phandle cache.  Avoids race condition that would arise
+	 * from removing cache entry when the associated node is deleted.
+	 */
+	of_free_phandle_cache();
+
 	ret_apply = 0;
 	ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
+
+	of_populate_phandle_cache();
+
 	if (ret) {
 		if (ret_apply)
 			devicetree_state_flags |= DTSF_REVERT_FAIL;