Messages in this thread | | | Date | Tue, 11 Dec 2018 16:36:36 -0500 | From | Jerome Glisse <> | Subject | Re: [PATCH] mm/mmu_notifier: fix mmu_notifier_range_init warning |
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On Tue, Dec 11, 2018 at 01:12:54PM -0800, David Rientjes wrote: > On Tue, 11 Dec 2018, Jerome Glisse wrote: > > > On Tue, Dec 11, 2018 at 09:04:43PM +0100, Arnd Bergmann wrote: > > > The macro version of mmu_notifier_range_init() for CONFIG_MMU_NOTIFIER=n > > > does not evaluate all its arguments, leading to a warning in one case: > > > > > > mm/migrate.c: In function 'migrate_vma_pages': > > > mm/migrate.c:2711:20: error: unused variable 'mm' [-Werror=unused-variable] > > > struct mm_struct *mm = vma->vm_mm; > > > > > > Pass down the 'mm' as into the inline function as well so gcc can > > > see why the variable exists. > > > > > > Fixes: 137d92bd73b1 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2") > > > > What about changing migrate.c (i actualy tried to do that everywhere in > > the patchset but i missed that spot) So we avoid one useless variable on > > such configuration: > > > > diff --git a/mm/migrate.c b/mm/migrate.c > > index f02bb4b22c1a..883fce631f47 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -2701,7 +2701,6 @@ static void migrate_vma_pages(struct migrate_vma *migrate) > > const unsigned long npages = migrate->npages; > > const unsigned long start = migrate->start; > > struct vm_area_struct *vma = migrate->vma; > > - struct mm_struct *mm = vma->vm_mm; > > struct mmu_notifier_range range; > > unsigned long addr, i; > > bool notified = false; > > @@ -2724,8 +2723,8 @@ static void migrate_vma_pages(struct migrate_vma *migrate) > > if (!notified) { > > notified = true; > > > > - mmu_notifier_range_init(&range, mm, addr, > > - migrate->end, > > + mmu_notifier_range_init(&range, vma->vm_mm, > > + addr, migrate->end, > > MMU_NOTIFY_CLEAR); > > mmu_notifier_invalidate_range_start(&range); > > } > > Wouldn't it be better to just declare mmu_notifier_range_init() as a > static inline function rather than a #define to avoid this warning?
The define trick is use to drop the event parameter so that we do not need to define the event value for CONFIG_MMU_NOTIFIER=n case.
Cheers, Jérôme
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