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SubjectRe: [PATCH v2 2/3] sched: add a macro to define bitops for task atomic flags
>> -static inline bool task_no_new_privs(struct task_struct *p)
>> -{
>> - return test_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
>> -}
>> -
>> -static inline void task_set_no_new_privs(struct task_struct *p)
>> -{
>> - set_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
>> -}
>> +#define TASK_PFA_BITOPS(name, func) \
>> +static inline bool task_##func(struct task_struct *p) \
>> +{ return test_bit(PFA_##name, &p->atomic_flags); } \
>> + \
>> +static inline void task_set_##func(struct task_struct *p) \
>> +{ set_bit(PFA_##name, &p->atomic_flags); } \
>> + \
>> +static inline void task_clear_##func(struct task_struct *p) \
>> +{ clear_bit(PFA_##name, &p->atomic_flags); }
>> +
>> +TASK_PFA_BITOPS(NO_NEW_PRIVS, no_new_privs)
>
> One thing I don't like about this is that task_clear_no_new_privs()
> ends up getting defined, and it should absolutely never be used. NNP
> should never be cleared or there could be security issues. I realize
> this isn't a very useful nit-pick, but I'd rather the function wasn't
> even available for someone to accidentally use. Maybe break up the
> macro with some kind of "write only" version like:
>
> #define TASK_PFA_BITOPS_WO(name, func) \
> static inline bool task_##func(struct task_struct *p) \
> { return test_bit(PFA_##name, &p->atomic_flags); } \
> static inline void task_set_##func(struct task_struct *p) \
> { set_bit(PFA_##name, &p->atomic_flags); }
>
> #define TASK_PFA_BITOPS(name, func) \
> TASK_PFA_BITOPS_WO(name, func); \
> static inline void task_clear_##func(struct task_struct *p) \
> { clear_bit(PFA_##name, &p->atomic_flags); }
>
> TASK_PFA_BITOPS_WO(NO_NEW_PRIVS, no_new_privs)
>
> And then all the new users can use TASK_PFA_BITOPS() normally since
> they expect to use "clear"?
>

Now I'm inclined to do this:

+#define TASK_PFA_TEST(name, func) \
+ static inline bool task_##func(struct task_struct *p) \
+ { return test_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_SET(name, func) \
+ static inline void task_set_##func(struct task_struct *p) \
+ { set_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_CLEAR(name, func) \
+ static inline void task_clear_##func(struct task_struct *p) \
+ { clear_bit(PFA_##name, &p->atomic_flags); }
+
+TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
+TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)



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