Messages in this thread | | | Date | Wed, 16 Aug 2023 15:27:21 +0800 | Subject | Re: [PATCH] cpufreq: cppc: Add missing error pointer check | From | "Liao, Chang" <> |
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Hi Viresh,
在 2023/8/16 11:46, Viresh Kumar 写道: > On 16-08-23, 03:05, Liao Chang wrote: >> The function cppc_freq_invariance_init() may failed to create >> kworker_fie, make it more robust by checking the return value to prevent >> an invalid pointer dereference in kthread_destroy_worker(), which called >> from cppc_freq_invariance_exit(). >> >> Signed-off-by: Liao Chang <liaochang1@huawei.com> >> --- >> drivers/cpufreq/cppc_cpufreq.c | 21 ++++++++++++++------- >> 1 file changed, 14 insertions(+), 7 deletions(-) > > I think why it was designed this way was to make the driver work, > without invariance support, in the worst case instead of just failing > completely. The invariance thing is a good to have feature, but not > really necessary and so failing probing the driver for that isn't > worth it. We should print all error messages though. > Thanks for pointing that out. I think you are right that the kworker created in the cppc driver is not the only arch_freq_scale updater, the ARCH provided updater has more priority than the driver, so the driver should still work even without kworker_fie supports.
If that is the case, i think the best thing to do is checking the error pointer and printing an error message before calling kthread_destroy() in cppc_freq_invariance_exit(), this is because at that point, it is really necessary to ensure the kworker_fie has been initialized as expected, otherwise it will raise a NULL pointer exception.
I hope this makes sense, thanks.
-- BR Liao, Chang
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