Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 8dbea644 authored by Frank Rowand's avatar Frank Rowand Committed by Greg Kroah-Hartman
Browse files

of: __of_detach_node() - remove node from phandle cache 



commit 5801169a2ed20003f771acecf3ac00574cf10a38 upstream.

Non-overlay dynamic devicetree node removal may leave the node in
the phandle cache.  Subsequent calls to of_find_node_by_phandle()
will incorrectly find the stale entry.  Remove the node from the
cache.

Add paranoia checks in of_find_node_by_phandle() as a second level
of defense (do not return cached node if detached, do not add node
to cache if detached).

Fixes: 0b3ce78e ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
Reported-by: default avatarMichael Bringmann <mwb@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: default avatarFrank Rowand <frank.rowand@sony.com>
Signed-off-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1cb5a033

drivers/of/base.c

+30 −1
Original line number Diff line number Diff line
@@ -161,6 +161,28 @@ int of_free_phandle_cache(void) 
late_initcall_sync(of_free_phandle_cache);

#endif



/*

 * Caller must hold devtree_lock.

 */

void __of_free_phandle_cache_entry(phandle handle)

{

	phandle masked_handle;

	struct device_node *np;



	if (!handle)

		return;



	masked_handle = handle & phandle_cache_mask;



	if (phandle_cache) {

		np = phandle_cache[masked_handle];

		if (np && handle == np->phandle) {

			of_node_put(np);

			phandle_cache[masked_handle] = NULL;

		}

	}

}



void of_populate_phandle_cache(void)

{

	unsigned long flags;
@@ -1169,11 +1191,18 @@ struct device_node *of_find_node_by_phandle(phandle handle) 
		if (phandle_cache[masked_handle] &&

		    handle == phandle_cache[masked_handle]->phandle)

			np = phandle_cache[masked_handle];

		if (np && of_node_check_flag(np, OF_DETACHED)) {

			WARN_ON(1); /* did not uncache np on node removal */

			of_node_put(np);

			phandle_cache[masked_handle] = NULL;

			np = NULL;

		}

	}



	if (!np) {

		for_each_of_allnodes(np)

			if (np->phandle == handle) {

			if (np->phandle == handle &&

			    !of_node_check_flag(np, OF_DETACHED)) {

				if (phandle_cache) {

					/* will put when removed from cache */

					of_node_get(np);

drivers/of/dynamic.c

+3 −0
Original line number Diff line number Diff line
@@ -268,6 +268,9 @@ void __of_detach_node(struct device_node *np) 
	}



	of_node_set_flag(np, OF_DETACHED);



	/* race with of_find_node_by_phandle() prevented by devtree_lock */

	__of_free_phandle_cache_entry(np->phandle);

}



/**

drivers/of/of_private.h

+4 −0
Original line number Diff line number Diff line
@@ -76,6 +76,10 @@ static inline void __of_detach_node_sysfs(struct device_node *np) {} 
int of_resolve_phandles(struct device_node *tree);

#endif



#if defined(CONFIG_OF_DYNAMIC)

void __of_free_phandle_cache_entry(phandle handle);

#endif



#if defined(CONFIG_OF_OVERLAY)

void of_overlay_mutex_lock(void);

void of_overlay_mutex_unlock(void);