ARM: OMAP2+: Fix device node reference counts

groeck · tmlind · commit 10e5778f5476 · 2017-03-04T08:27:46.000-08:00
After commit 0549bde ("of: fix of_node leak caused in of_find_node_opts_by_path"), the following error may be reported when running omap images. OF: ERROR: Bad of_node_put() on /ocp@68000000 CPU: 0 PID: 0 Comm: swapper Not tainted 4.10.0-rc7-next-20170210 #1 Hardware name: Generic OMAP3-GP (Flattened Device Tree) [<c0310604>] (unwind_backtrace) from [<c030bbf4>] (show_stack+0x10/0x14) [<c030bbf4>] (show_stack) from [<c05add8c>] (dump_stack+0x98/0xac) [<c05add8c>] (dump_stack) from [<c05af1b0>] (kobject_release+0x48/0x7c) [<c05af1b0>] (kobject_release) from [<c0ad1aa4>] (of_find_node_by_name+0x74/0x94) [<c0ad1aa4>] (of_find_node_by_name) from [<c1215bd4>] (omap3xxx_hwmod_is_hs_ip_block_usable+0x24/0x2c) [<c1215bd4>] (omap3xxx_hwmod_is_hs_ip_block_usable) from [<c1215d5c>] (omap3xxx_hwmod_init+0x180/0x274) [<c1215d5c>] (omap3xxx_hwmod_init) from [<c120faa8>] (omap3_init_early+0xa0/0x11c) [<c120faa8>] (omap3_init_early) from [<c120fb2c>] (omap3430_init_early+0x8/0x30) [<c120fb2c>] (omap3430_init_early) from [<c1204710>] (setup_arch+0xc04/0xc34) [<c1204710>] (setup_arch) from [<c1200948>] (start_kernel+0x68/0x38c) [<c1200948>] (start_kernel) from [<8020807c>] (0x8020807c) of_find_node_by_name() drops the reference to the passed device node. The commit referenced above exposes this problem. To fix the problem, use of_get_child_by_name() instead of of_find_node_by_name(); of_get_child_by_name() does not drop the reference count of passed device nodes. While semantically different, we only look for immediate children of the passed device node, so of_get_child_by_name() is a more appropriate function to use anyway. Release the reference to the device node obtained with of_get_child_by_name() after it is no longer needed to avoid another device node leak. While at it, clean up the code and change the return type of omap3xxx_hwmod_is_hs_ip_block_usable() to bool to match its use and the return type of of_device_is_available(). Cc: Qi Hou <qi.hou@windriver.com> Cc: Peter Rosin <peda@axentia.se> Cc: Rob Herring <robh@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
@@ -3131,16 +3131,20 @@ static struct omap_hwmod_ocp_if *omap3xxx_dss_hwmod_ocp_ifs[] __initdata = {
  * Return: 0 if device named @dev_name is not likely to be accessible,
  * or 1 if it is likely to be accessible.
  */
-static int __init omap3xxx_hwmod_is_hs_ip_block_usable(struct device_node *bus,
-						       const char *dev_name)
+static bool __init omap3xxx_hwmod_is_hs_ip_block_usable(struct device_node *bus,
+							const char *dev_name)
 {
+	struct device_node *node;
+	bool available;
+
 	if (!bus)
-		return (omap_type() == OMAP2_DEVICE_TYPE_GP) ? 1 : 0;
+		return omap_type() == OMAP2_DEVICE_TYPE_GP;
 
-	if (of_device_is_available(of_find_node_by_name(bus, dev_name)))
-		return 1;
+	node = of_get_child_by_name(bus, dev_name);
+	available = of_device_is_available(node);
+	of_node_put(node);
 
-	return 0;
+	return available;
 }
 
 int __init omap3xxx_hwmod_init(void)
