Hi Eugene,
This already got merged into -mm, but ...
On Sun, 19 Aug 2007, Eugene Teo wrote:
>
> tsk->exit_state can only be 0, EXIT_ZOMBIE, or EXIT_DEAD. A non-zero test
> is the same as tsk->exit_state & (EXIT_ZOMBIE | EXIT_DEAD), so just testing
> tsk->exit_state is sufficient.
... IMHO this change harms the readability of the code.
> +++ b/fs/proc/array.c
> @@ -145,8 +145,7 @@ static inline const char *get_task_state(struct
> task_struct *tsk)
> TASK_UNINTERRUPTIBLE |
> TASK_STOPPED |
> TASK_TRACED)) |
> - (tsk->exit_state & (EXIT_ZOMBIE |
> - EXIT_DEAD));
> + tsk->exit_state;
Here, for example, the code is /purposefully/ enumerating all the task
states, probably it makes sense to explicitly enumerate the exit states
as well?
> +++ b/kernel/fork.c
> @@ -115,7 +115,7 @@ EXPORT_SYMBOL(free_task);
>
> void __put_task_struct(struct task_struct *tsk)
> {
> - WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
> + WARN_ON(!tsk->exit_state);
> +++ b/kernel/sched.c
> @@ -5190,7 +5190,7 @@ static void migrate_dead(unsigned int dead_cpu, struct
> task_struct *p)
> struct rq *rq = cpu_rq(dead_cpu);
>
> /* Must be exiting, otherwise would be on tasklist. */
> - BUG_ON(p->exit_state != EXIT_ZOMBIE && p->exit_state != EXIT_DEAD);
> + BUG_ON(!p->exit_state);
Regarding above two changes -- agreed, we want to catch /any/ exiting task
state, so (!p->exit_state) is /correct/, but still, enumerating those
explicitly helps readability. And although it's unlikely, in the future,
we may have an exit_state value for which we may _not_ want to complain
(WARN or BUG) in this code. So I'd still vote to keep the code explicit
like it was ...
Satyam
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