PM / devfreq: Fix possible null pointer issue in devfreq_add_governor()

When a user removes a governor using devfreq_remove_governor(), if
the current device is using this governor, devfreq->governor will
be set to NULL. When the user registers any governor
using devfreq_add_governor(), since devfreq->governor is NULL, a
null pointer error occurs in strncmp().

For example: A user loads the userspace gov through a module, then
a device selects userspace. When unloading the userspace module and
then loading it again, the null pointer error occurs:

Unable to handle kernel NULL pointer dereference at virtual address
0000000000000010
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
*******************skip *********************
Call trace:
__pi_strncmp+0x20/0x1b8
devfreq_userspace_init+0x1c/0xff8 [governor_userspace]
do_one_initcall+0x4c/0x278
do_init_module+0x5c/0x218
load_module+0x1f1c/0x1fc8
init_module_from_file+0x8c/0xd0
__arm64_sys_finit_module+0x220/0x3d8
invoke_syscall+0x48/0x110
el0_svc_common.constprop.0+0xbc/0xe8
do_el0_svc+0x20/0x30
el0_svc+0x24/0xb8
el0t_64_sync_handler+0xb8/0xc0
el0t_64_sync+0x14c/0x150

To fix this issue, remove the list_for_each_entry() logic, as
find_devfreq_governor() has already checked for the existence of
governor with the same name. This makes it impossible to find a
duplicate governor in the list, so the subsequent logic is
unreachable and can be removed.

Fixes: 1b5c1be2c88e ("PM / devfreq: map devfreq drivers to governor using name")
Signed-off-by: Yaxiong Tian <tianyaxiong@kylinos.cn>
Co-developed-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Jie Zhan <zhanjie9@hisilicon.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://patchwork.kernel.org/project/linux-pm/patch/20260401033046.67482-1-tianyaxiong@kylinos.cn/

0 files changed, 0 insertions, 0 deletions