Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 24 Jan 2024 16:08:05 +0800 | Subject | Re: [PATCH v2 1/2] sched/fair: Return NULL when entity isn't a task in task_of() | From | Yajun Deng <> |
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On 2024/1/23 11:48, Steven Rostedt wrote: > On Wed, 6 Dec 2023 14:33:59 +0800 > Yajun Deng <yajun.deng@linux.dev> wrote: > >> Before calling task_of(), we need to make sure that the entity is a task. >> There is also a warning in task_of() if the entity isn't a task. That >> means we need to check the entity twice. If the entity isn't a task, > Does it really check it twice? Have you disassembled it to see if the code > is any better? > > #define entity_is_task(se) (!se->my_q) > static inline struct task_struct *task_of(struct sched_entity *se) > { > SCHED_WARN_ON(!entity_is_task(se)); > return container_of(se, struct task_struct, se); > } > > The above is a macro and a static inline, which means that the compiler > should optimized out that second check.
Yes, the second check should be optimized.
> >> return the task struct is meaningless. >> >> Return NULL when entity isn't a task in task_of(), and call task_of() >> instead of entity_is_task() when we need a task_struct. > I'm not against the change, as it could be considered a clean up. But it is > up to the sched maintainers to decide if it's worth the churn.
Return NULL in task_of() makes the code cleaner.
> > -- Steve > > >> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
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