On Tue, Mar 19, 2024 at 09:22:03AM +0800, Leizhen (ThunderTown) wrote:
>
>
> On 2024/3/19 0:33, Mike Rapoport wrote:
> > On Mon, Mar 18, 2024 at 09:57:14PM +0800, thunder.leizhen@xxxxxxxxxxxxxxx wrote:
> >> From: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> >>
> >> The local variable 'page_poisoning_requested' is assigned true at only
> >> one point. It can be eliminated by moving the code that depends on it
> >> to the location where it is assigned true. This also make the moved
> >> code to be compiled only if CONFIG_PAGE_POISONING is set.
> >
> > I don't see it as much of an improvement and code readability becomes worse
> > IMO.
>
> Yes, the moved branch will be optimized by the compiler if CONFIG_PAGE_POISONING is
> not set. But for a reader, he can simply skip over that moved branch when
> CONFIG_PAGE_POISONING is not set.
Saving one branch at init does not justify the churn and reduced
readability.
> >> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> >> ---
> >> mm/mm_init.c | 17 +++++++----------
> >> 1 file changed, 7 insertions(+), 10 deletions(-)
> >>
> >> diff --git a/mm/mm_init.c b/mm/mm_init.c
> >> index 549e76af8f82a8e..3eb217130bcb2b5 100644
> >> --- a/mm/mm_init.c
> >> +++ b/mm/mm_init.c
> >> @@ -2614,7 +2614,6 @@ DEFINE_STATIC_KEY_MAYBE(CONFIG_DEBUG_VM, check_pages_enabled);
> >> */
> >> static void __init mem_debugging_and_hardening_init(void)
> >> {
> >> - bool page_poisoning_requested = false;
> >> bool want_check_pages = false;
> >>
> >> #ifdef CONFIG_PAGE_POISONING
> >> @@ -2626,18 +2625,16 @@ static void __init mem_debugging_and_hardening_init(void)
> >> (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
> >> debug_pagealloc_enabled())) {
> >> static_branch_enable(&_page_poisoning_enabled);
> >> - page_poisoning_requested = true;
> >> want_check_pages = true;
> >> - }
> >> -#endif
> >>
> >> - if ((_init_on_alloc_enabled_early || _init_on_free_enabled_early) &&
> >> - page_poisoning_requested) {
> >> - pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
> >> - "will take precedence over init_on_alloc and init_on_free\n");
> >> - _init_on_alloc_enabled_early = false;
> >> - _init_on_free_enabled_early = false;
> >> + if (_init_on_alloc_enabled_early || _init_on_free_enabled_early) {
> >> + pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, "
> >> + "will take precedence over init_on_alloc and init_on_free\n");
> >> + _init_on_alloc_enabled_early = false;
> >> + _init_on_free_enabled_early = false;
> >> + }
> >> }
> >> +#endif
> >>
> >> if (_init_on_alloc_enabled_early) {
> >> want_check_pages = true;
> >> --
> >> 2.34.1
> >>
> >
>
> --
> Regards,
> Zhen Lei
>
--
Sincerely yours,
Mike.
