diff options
| author | Frank Rowand <frank.rowand@sony.com> | 2018-12-18 20:40:03 +0100 |
|---|---|---|
| committer | Rob Herring <robh@kernel.org> | 2018-12-21 19:42:36 +0100 |
| commit | 5801169a2ed20003f771acecf3ac00574cf10a38 (patch) | |
| tree | 56bcdc99f2d669033eea3c4308e52419a44ddc7e /drivers/of | |
| parent | of: of_node_get()/of_node_put() nodes held in phandle cache (diff) | |
| download | linux-5801169a2ed20003f771acecf3ac00574cf10a38.tar.xz linux-5801169a2ed20003f771acecf3ac00574cf10a38.zip | |
of: __of_detach_node() - remove node from phandle cache
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: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()")
Reported-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Diffstat (limited to 'drivers/of')
| -rw-r--r-- | drivers/of/base.c | 31 | ||||
| -rw-r--r-- | drivers/of/dynamic.c | 3 | ||||
| -rw-r--r-- | drivers/of/of_private.h | 4 |
3 files changed, 37 insertions, 1 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c index 4da1c688995b..5226e898476e 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -169,6 +169,28 @@ 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; @@ -1214,11 +1236,18 @@ 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); diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index b4e5b90cb314..a09c1c3cf831 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -277,6 +277,9 @@ 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); } /** diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 5d1567025358..24786818e32e 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -84,6 +84,10 @@ 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); |