On Thu, Jun 29, 2023 at 8:36 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Thu, Jun 29, 2023 at 07:04:33PM -0700, Suren Baghdasaryan wrote:
> > Change folio_lock_or_retry to accept vm_fault struct and return the
> > vm_fault_t directly.
>
> I thought we decided to call this folio_lock_fault()?
>
> > +static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
> > + struct vm_fault *vmf)
> > {
> > might_sleep();
> > - return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
> > + return folio_trylock(folio) ? 0 : __folio_lock_or_retry(folio, vmf);
>
> No, don't use the awful ternary operator. The || form is used
> everywhere else.
Ok, but folio_trylock() returns a boolean while folio_lock_or_retry
should return vm_fault_t. How exactly do you suggest changing this?
Something like this perhaps:
static inline vm_fault_t folio_lock_or_retry(struct folio *folio,
struct vm_fault *vmf)
{
might_sleep();
if (folio_trylock(folio))
return 0;
return __folio_lock_or_retry(folio, mm, flags);
}
?
>
> > /*
> > * Return values:
> > - * true - folio is locked; mmap_lock is still held.
> > - * false - folio is not locked.
> > + * 0 - folio is locked.
> > + * VM_FAULT_RETRY - folio is not locked.
>
> I don't think we want to be so prescriptive here. It returns non-zero
> if the folio is not locked. The precise value is not something that
> callers should depend on.
Ok, I'll change it to "non-zero" here.
>
