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SubjectRe: [PATCH] sched: make struct task_struct::state 32-bit
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On 02/09/2019 22:05, Alexey Dobriyan wrote:
> 32-bit accesses are shorter than 64-bit accesses on x86_64.
> Nothing uses 64-bitness of ->state.
>
> Space savings are ~2KB on F30 kernel config.
>
> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
> ---
>
> arch/ia64/kernel/perfmon.c | 4 ++--
> block/blk-mq.c | 2 +-
> drivers/md/dm.c | 4 ++--
> fs/userfaultfd.c | 2 +-
> include/linux/sched.h | 6 +++---
> include/linux/sched/debug.h | 2 +-
> include/linux/sched/signal.h | 2 +-
> kernel/freezer.c | 2 +-
> kernel/kthread.c | 4 ++--
> kernel/locking/mutex.c | 6 +++---
> kernel/locking/semaphore.c | 2 +-
> kernel/rcu/rcutorture.c | 4 ++--
> kernel/rcu/tree_stall.h | 6 +++---
> kernel/sched/core.c | 8 ++++----
> lib/syscall.c | 2 +-
> 15 files changed, 28 insertions(+), 28 deletions(-)
>

It looks like you missed a few places. There's a long prev_state in
sched/core.c::finish_task_switch() for instance.

I suppose that's where coccinelle oughta help but I'm really not fluent
in that. Is there a way to make it match p.state accesses with p task_struct?
And if so, can we make it change the type of the variable being read from
/ written to?

How did you come up with this changeset, did you pickaxe for some regexp?

[...]

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