On Wed, Sep 15, 2021 at 10:10 AM laurentiu.tudor@nxp.com wrote:

From: Laurentiu Tudor laurentiu.tudor@nxp.com

software_node_notify(), on KOBJ_REMOVE drops the refcount twice on managed software nodes, thus leading to underflow errors. Balance the refcount by bumping it in the device_create_managed_software_node() function.

The error [1] was encountered after adding a .shutdown() op to our fsl-mc-bus driver.

[1] pc : refcount_warn_saturate+0xf8/0x150 lr : refcount_warn_saturate+0xf8/0x150 sp : ffff80001009b920 x29: ffff80001009b920 x28: ffff1a2420318000 x27: 0000000000000000 x26: ffffccac15e7a038 x25: 0000000000000008 x24: ffffccac168e0030 x23: ffff1a2428a82000 x22: 0000000000080000 x21: ffff1a24287b5000 x20: 0000000000000001 x19: ffff1a24261f4400 x18: ffffffffffffffff x17: 6f72645f726f7272 x16: 0000000000000000 x15: ffff80009009b607 x14: 0000000000000000 x13: ffffccac16602670 x12: 0000000000000a17 x11: 000000000000035d x10: ffffccac16602670 x9 : ffffccac16602670 x8 : 00000000ffffefff x7 : ffffccac1665a670 x6 : ffffccac1665a670 x5 : 0000000000000000 x4 : 0000000000000000 x3 : 00000000ffffffff x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff1a2420318000 Call trace: refcount_warn_saturate+0xf8/0x150 kobject_put+0x10c/0x120 software_node_notify+0xd8/0x140 device_platform_notify+0x4c/0xb4 device_del+0x188/0x424 fsl_mc_device_remove+0x2c/0x4c rebofind sp.c__fsl_mc_device_remove+0x14/0x2c device_for_each_child+0x5c/0xac dprc_remove+0x9c/0xc0 fsl_mc_driver_remove+0x28/0x64 __device_release_driver+0x188/0x22c device_release_driver+0x30/0x50 bus_remove_device+0x128/0x134 device_del+0x16c/0x424 fsl_mc_bus_remove+0x8c/0x114 fsl_mc_bus_shutdown+0x14/0x20 platform_shutdown+0x28/0x40 device_shutdown+0x15c/0x330 __do_sys_reboot+0x218/0x2a0 __arm64_sys_reboot+0x28/0x34 invoke_syscall+0x48/0x114 el0_svc_common+0x40/0xdc do_el0_svc+0x2c/0x94 el0_svc+0x2c/0x54 el0t_64_sync_handler+0xa8/0x12c el0t_64_sync+0x198/0x19c ---[ end trace 32eb1c71c7d86821 ]---

Fixes: 151f6ff78cdf ("software node: Provide replacement for device_add_properties()") Reported-by: Jon Nettleton jon@solid-run.com Suggested-by: Heikki Krogerus heikki.krogerus@linux.intel.com Reviewed-by: Heikki Krogerus heikki.krogerus@linux.intel.com Signed-off-by: Laurentiu Tudor laurentiu.tudor@nxp.com Cc: stable@vger.kernel.org

---

Changes since v2:

• added Fixes: tag
• Cc-ed stable

Changes since v1:

• added Heikki's Reviewed-by: (Thanks!)

Changes since RFC:

• use software_node_notify(KOBJ_ADD) instead of directly bumping refcount (Heikki)

drivers/base/swnode.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c index d1f1a8240120..bdb50a06c82a 100644 --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -1113,6 +1113,9 @@ int device_create_managed_software_node(struct device *dev, to_swnode(fwnode)->managed = true; set_secondary_fwnode(dev, fwnode);

•   if (device_is_registered(dev))
  

•           software_node_notify(dev, KOBJ_ADD);
  

•   return 0;
  

} EXPORT_SYMBOL_GPL(device_create_managed_software_node); --

Applied as 5.15-rc material, thanks!