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author | Herve Codina <herve.codina@bootlin.com> | 2023-11-14 16:26:55 +0100 |
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committer | Petr Mladek <pmladek@suse.com> | 2023-12-06 11:06:59 +0100 |
commit | 5c47251e8c4903111608ddcba2a77c0c425c247c (patch) | |
tree | 27bd1276083b5cdf3f27b8600eae65d6fb0bfb53 | |
parent | 2a80532c0745e140852e6b579bbe8371332bb45d (diff) | |
download | linux-5c47251e8c4903111608ddcba2a77c0c425c247c.tar.gz linux-5c47251e8c4903111608ddcba2a77c0c425c247c.tar.bz2 linux-5c47251e8c4903111608ddcba2a77c0c425c247c.zip |
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.c | 11 |
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; |