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authorHerve Codina <herve.codina@bootlin.com>2023-11-14 16:26:55 +0100
committerPetr Mladek <pmladek@suse.com>2023-12-06 11:06:59 +0100
commit5c47251e8c4903111608ddcba2a77c0c425c247c (patch)
tree27bd1276083b5cdf3f27b8600eae65d6fb0bfb53
parent2a80532c0745e140852e6b579bbe8371332bb45d (diff)
lib/vsprintf: Fix %pfwf when current node refcount == 0
A refcount issue can appeared in __fwnode_link_del() due to the pr_debug() call: WARNING: CPU: 0 PID: 901 at lib/refcount.c:25 refcount_warn_saturate+0xe5/0x110 Call Trace: <TASK> ... of_node_get+0x1e/0x30 of_fwnode_get+0x28/0x40 fwnode_full_name_string+0x34/0x90 fwnode_string+0xdb/0x140 ... vsnprintf+0x17b/0x630 ... __fwnode_link_del+0x25/0xa0 fwnode_links_purge+0x39/0xb0 of_node_release+0xd9/0x180 ... Indeed, an fwnode (of_node) is being destroyed and so, of_node_release() is called because the of_node refcount reached 0. From of_node_release() several function calls are done and lead to a pr_debug() calls with %pfwf to print the fwnode full name. The issue is not present if we change %pfwf to %pfwP. To print the full name, %pfwf iterates over the current node and its parents and obtain/drop a reference to all nodes involved. In order to allow to print the full name (%pfwf) of a node while it is being destroyed, do not obtain/drop a reference to this current node. Fixes: a92eb7621b9f ("lib/vsprintf: Make use of fwnode API to obtain node names and separators") Cc: stable@vger.kernel.org Signed-off-by: Herve Codina <herve.codina@bootlin.com> Reviewed-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20231114152655.409331-1-herve.codina@bootlin.com
-rw-r--r--lib/vsprintf.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 3e3733a7084f..552738f14275 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2111,15 +2111,20 @@ char *fwnode_full_name_string(struct fwnode_handle *fwnode, char *buf,
/* Loop starting from the root node to the current node. */
for (depth = fwnode_count_parents(fwnode); depth >= 0; depth--) {
- struct fwnode_handle *__fwnode =
- fwnode_get_nth_parent(fwnode, depth);
+ /*
+ * Only get a reference for other nodes (i.e. parent nodes).
+ * fwnode refcount may be 0 here.
+ */
+ struct fwnode_handle *__fwnode = depth ?
+ fwnode_get_nth_parent(fwnode, depth) : fwnode;
buf = string(buf, end, fwnode_get_name_prefix(__fwnode),
default_str_spec);
buf = string(buf, end, fwnode_get_name(__fwnode),
default_str_spec);
- fwnode_handle_put(__fwnode);
+ if (depth)
+ fwnode_handle_put(__fwnode);
}
return buf;