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    Subject[PATCH 5.18 310/879] cpufreq: governor: Use kobject release() method to free dbs_data
    Date
    From: Kevin Hao <haokexin@gmail.com>

    [ Upstream commit a85ee6401a47ae3fc64ba506cacb3e7873823c65 ]

    The struct dbs_data embeds a struct gov_attr_set and
    the struct gov_attr_set embeds a kobject. Since every kobject must have
    a release() method and we can't use kfree() to free it directly,
    so introduce cpufreq_dbs_data_release() to release the dbs_data via
    the kobject::release() method. This fixes the calltrace like below:

    ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x34
    WARNING: CPU: 12 PID: 810 at lib/debugobjects.c:505 debug_print_object+0xb8/0x100
    Modules linked in:
    CPU: 12 PID: 810 Comm: sh Not tainted 5.16.0-next-20220120-yocto-standard+ #536
    Hardware name: Marvell OcteonTX CN96XX board (DT)
    pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
    pc : debug_print_object+0xb8/0x100
    lr : debug_print_object+0xb8/0x100
    sp : ffff80001dfcf9a0
    x29: ffff80001dfcf9a0 x28: 0000000000000001 x27: ffff0001464f0000
    x26: 0000000000000000 x25: ffff8000090e3f00 x24: ffff80000af60210
    x23: ffff8000094dfb78 x22: ffff8000090e3f00 x21: ffff0001080b7118
    x20: ffff80000aeb2430 x19: ffff800009e8f5e0 x18: 0000000000000000
    x17: 0000000000000002 x16: 00004d62e58be040 x15: 013590470523aff8
    x14: ffff8000090e1828 x13: 0000000001359047 x12: 00000000f5257d14
    x11: 0000000000040591 x10: 0000000066c1ffea x9 : ffff8000080d15e0
    x8 : ffff80000a1765a8 x7 : 0000000000000000 x6 : 0000000000000001
    x5 : ffff800009e8c000 x4 : ffff800009e8c760 x3 : 0000000000000000
    x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0001474ed040
    Call trace:
    debug_print_object+0xb8/0x100
    __debug_check_no_obj_freed+0x1d0/0x25c
    debug_check_no_obj_freed+0x24/0xa0
    kfree+0x11c/0x440
    cpufreq_dbs_governor_exit+0xa8/0xac
    cpufreq_exit_governor+0x44/0x90
    cpufreq_set_policy+0x29c/0x570
    store_scaling_governor+0x110/0x154
    store+0xb0/0xe0
    sysfs_kf_write+0x58/0x84
    kernfs_fop_write_iter+0x12c/0x1c0
    new_sync_write+0xf0/0x18c
    vfs_write+0x1cc/0x220
    ksys_write+0x74/0x100
    __arm64_sys_write+0x28/0x3c
    invoke_syscall.constprop.0+0x58/0xf0
    do_el0_svc+0x70/0x170
    el0_svc+0x54/0x190
    el0t_64_sync_handler+0xa4/0x130
    el0t_64_sync+0x1a0/0x1a4
    irq event stamp: 189006
    hardirqs last enabled at (189005): [<ffff8000080849d0>] finish_task_switch.isra.0+0xe0/0x2c0
    hardirqs last disabled at (189006): [<ffff8000090667a4>] el1_dbg+0x24/0xa0
    softirqs last enabled at (188966): [<ffff8000080106d0>] __do_softirq+0x4b0/0x6a0
    softirqs last disabled at (188957): [<ffff80000804a618>] __irq_exit_rcu+0x108/0x1a4

    [ rjw: Because can be freed by the gov_attr_set_put() in
    cpufreq_dbs_governor_exit() now, it is also necessary to put the
    invocation of the governor ->exit() callback into the new
    cpufreq_dbs_data_release() function. ]

    Fixes: c4435630361d ("cpufreq: governor: New sysfs show/store callbacks for governor tunables")
    Signed-off-by: Kevin Hao <haokexin@gmail.com>
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/cpufreq/cpufreq_governor.c | 20 +++++++++++++-------
    drivers/cpufreq/cpufreq_governor.h | 1 +
    2 files changed, 14 insertions(+), 7 deletions(-)

    diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
    index 0d42cf8b88d8..85da677c43d6 100644
    --- a/drivers/cpufreq/cpufreq_governor.c
    +++ b/drivers/cpufreq/cpufreq_governor.c
    @@ -388,6 +388,15 @@ static void free_policy_dbs_info(struct policy_dbs_info *policy_dbs,
    gov->free(policy_dbs);
    }

    +static void cpufreq_dbs_data_release(struct kobject *kobj)
    +{
    + struct dbs_data *dbs_data = to_dbs_data(to_gov_attr_set(kobj));
    + struct dbs_governor *gov = dbs_data->gov;
    +
    + gov->exit(dbs_data);
    + kfree(dbs_data);
    +}
    +
    int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
    {
    struct dbs_governor *gov = dbs_governor_of(policy);
    @@ -425,6 +434,7 @@ int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
    goto free_policy_dbs_info;
    }

    + dbs_data->gov = gov;
    gov_attr_set_init(&dbs_data->attr_set, &policy_dbs->list);

    ret = gov->init(dbs_data);
    @@ -447,6 +457,7 @@ int cpufreq_dbs_governor_init(struct cpufreq_policy *policy)
    policy->governor_data = policy_dbs;

    gov->kobj_type.sysfs_ops = &governor_sysfs_ops;
    + gov->kobj_type.release = cpufreq_dbs_data_release;
    ret = kobject_init_and_add(&dbs_data->attr_set.kobj, &gov->kobj_type,
    get_governor_parent_kobj(policy),
    "%s", gov->gov.name);
    @@ -488,13 +499,8 @@ void cpufreq_dbs_governor_exit(struct cpufreq_policy *policy)

    policy->governor_data = NULL;

    - if (!count) {
    - if (!have_governor_per_policy())
    - gov->gdbs_data = NULL;
    -
    - gov->exit(dbs_data);
    - kfree(dbs_data);
    - }
    + if (!count && !have_governor_per_policy())
    + gov->gdbs_data = NULL;

    free_policy_dbs_info(policy_dbs, gov);

    diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
    index a5a0bc3cc23e..168c23fd7fca 100644
    --- a/drivers/cpufreq/cpufreq_governor.h
    +++ b/drivers/cpufreq/cpufreq_governor.h
    @@ -37,6 +37,7 @@ enum {OD_NORMAL_SAMPLE, OD_SUB_SAMPLE};
    /* Governor demand based switching data (per-policy or global). */
    struct dbs_data {
    struct gov_attr_set attr_set;
    + struct dbs_governor *gov;
    void *tuners;
    unsigned int ignore_nice_load;
    unsigned int sampling_rate;
    --
    2.35.1


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