Messages in this thread | | | Date | Thu, 17 Aug 2023 10:33:13 +0800 | Subject | Re: [PATCH v2] cpufreq: cppc: Set fie_disabled to FIE_DISABLED if fails to create kworker_fie | From | "Liao, Chang" <> |
| |
在 2023/8/16 18:37, Viresh Kumar 写道: > On 16-08-23, 09:49, Liao Chang wrote: >> The function cppc_freq_invariance_init() may failed to create >> kworker_fie, make it more robust by setting fie_disabled to FIE_DISBALED >> to prevent an invalid pointer dereference in kthread_destroy_worker(), >> which called from cppc_freq_invariance_exit(). >> >> Link: https://lore.kernel.org/all/20230816034630.a4hvsj373q6aslk3@vireshk-i7/ >> >> Signed-off-by: Liao Chang <liaochang1@huawei.com> >> --- >> drivers/cpufreq/cppc_cpufreq.c | 28 ++++++++++++++++------------ >> 1 file changed, 16 insertions(+), 12 deletions(-) >> >> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c >> index 022e3555407c..bff4cde06083 100644 >> --- a/drivers/cpufreq/cppc_cpufreq.c >> +++ b/drivers/cpufreq/cppc_cpufreq.c >> @@ -220,6 +220,15 @@ static void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy) >> } >> } >> >> +static void cppc_freq_invariance_exit(void) >> +{ >> + if (fie_disabled) >> + return; >> + >> + kthread_destroy_worker(kworker_fie); >> + kworker_fie = NULL; >> +} >> + >> static void __init cppc_freq_invariance_init(void) >> { >> struct sched_attr attr = { >> @@ -249,27 +258,22 @@ static void __init cppc_freq_invariance_init(void) >> return; >> >> kworker_fie = kthread_create_worker(0, "cppc_fie"); >> - if (IS_ERR(kworker_fie)) >> + if (IS_ERR(kworker_fie)) { >> + pr_warn("%s: failed to create kworker_fie: %ld\n", __func__, >> + PTR_ERR(kworker_fie)); >> + fie_disabled = FIE_DISABLED; >> return; >> + } >> >> ret = sched_setattr_nocheck(kworker_fie->task, &attr); >> if (ret) { >> pr_warn("%s: failed to set SCHED_DEADLINE: %d\n", __func__, >> ret); >> - kthread_destroy_worker(kworker_fie); >> - return; >> + cppc_freq_invariance_exit(); > > I don't really like this change, there aren't a lot of things that we > need to do here on cleanup, but just kthread_destroy_worker(). Calling > it directly makes more sense I guess.
OK,I will simplify code in next revisoin.
> >> + fie_disabled = FIE_DISABLED; >> } >> } >> >> -static void cppc_freq_invariance_exit(void) >> -{ >> - if (fie_disabled) >> - return; >> - >> - kthread_destroy_worker(kworker_fie); > >> - kworker_fie = NULL; > > I don't see the point of this line. Probably it can be dropped.
I agree with you, when fie_disbaled is set to FIE_DISABLED and kthred_destroy_worker() is called, the driver has no chance to access the invalid kworker_fie pointer.
Thanks.
> >> -} >> - >> #else >> static inline void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy) >> { >> -- >> 2.34.1 >
-- BR Liao, Chang
| |