linux-kernel - [PATCH] ARM: OMAP2+: Grab reference to device nodes where needed

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Date:   Sat, 11 Feb 2017 14:59:08 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Paul Walmsley <paul@...an.com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Russell King <linux@...linux.org.uk>,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        Qi Hou <qi.hou@...driver.com>, Peter Rosin <peda@...ntia.se>,
        Rob Herring <robh@...nel.org>
Subject: [PATCH] ARM: OMAP2+: Grab reference to device nodes where needed

After commit '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@...00000
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,
so it is necessary to grab an extra one if it is still needed after the
call.

Cc: Qi Hou <qi.hou@...driver.com>
Cc: Peter Rosin <peda@...ntia.se>
Cc: Rob Herring <robh@...nel.org>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 arch/arm/mach-omap2/omap_hwmod_3xxx_data.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
index 56f917ec8621..d4ca1e3964c3 100644
--- a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
+++ b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c
@@ -3117,6 +3117,7 @@ static int __init omap3xxx_hwmod_is_hs_ip_block_usable(struct device_node *bus,
 	if (!bus)
 		return (omap_type() == OMAP2_DEVICE_TYPE_GP) ? 1 : 0;
 
+	of_node_get(bus);
 	if (of_device_is_available(of_find_node_by_name(bus, dev_name)))
 		return 1;
 
@@ -3189,15 +3190,20 @@ int __init omap3xxx_hwmod_init(void)
 
 	if (h_sham && omap3xxx_hwmod_is_hs_ip_block_usable(bus, "sham")) {
 		r = omap_hwmod_register_links(h_sham);
-		if (r < 0)
+		if (r < 0) {
+			of_node_put(bus);
 			return r;
+		}
 	}
 
 	if (h_aes && omap3xxx_hwmod_is_hs_ip_block_usable(bus, "aes")) {
 		r = omap_hwmod_register_links(h_aes);
-		if (r < 0)
+		if (r < 0) {
+			of_node_put(bus);
 			return r;
+		}
 	}
+	of_node_put(bus);
 
 	/*
 	 * Register hwmod links specific to certain ES levels of a
-- 
2.7.4