| Message ID | 1488639731-8047-1-git-send-email-linux@roeck-us.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
* Guenter Roeck <linux@roeck-us.net> [170304 07:04]: > After commit 0549bde0fcb1 ("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> > --- > v3: Add commit SHA of patch exposing the problem > Clarify that it does not cause the problem but exposes it > Split into two patches > v2: Change subject ('Grab reference to device nodes where needed' > didn't really cover all the changes made) > Use of_get_child_by_name() instead of of_find_node_by_name() > Drop references to device nodes as needed > Change return type of omap3xxx_hwmod_is_hs_ip_block_usable() > to bool Thanks for the updates, applying both into omap-for-v4.11/fixes. Regards, Tony
diff --git a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c index 56f917ec8621..44b5f9bbdde6 100644 --- a/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c +++ b/arch/arm/mach-omap2/omap_hwmod_3xxx_data.c @@ -3111,16 +3111,20 @@ 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)
After commit 0549bde0fcb1 ("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> --- v3: Add commit SHA of patch exposing the problem Clarify that it does not cause the problem but exposes it Split into two patches v2: Change subject ('Grab reference to device nodes where needed' didn't really cover all the changes made) Use of_get_child_by_name() instead of of_find_node_by_name() Drop references to device nodes as needed Change return type of omap3xxx_hwmod_is_hs_ip_block_usable() to bool arch/arm/mach-omap2/omap_hwmod_3xxx_data.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)