lkml.org 
[lkml]   [2020]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RESEND PATCH] percpu_ref: Fix comment regarding percpu_ref_init flags

[snip]

> > > diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
> > > index 4f6c6ebbbbde..48d7fcff70b6 100644
> > > --- a/lib/percpu-refcount.c
> > > +++ b/lib/percpu-refcount.c
> > > @@ -50,9 +50,9 @@ static unsigned long __percpu *percpu_count_ptr(struct percpu_ref *ref)
> > > * @flags: PERCPU_REF_INIT_* flags
> > > * @gfp: allocation mask to use
> > > *
> > > - * Initializes @ref. If @flags is zero, @ref starts in percpu mode with a
> > > - * refcount of 1; analagous to atomic_long_set(ref, 1). See the
> > > - * definitions of PERCPU_REF_INIT_* flags for flag behaviors.
> > > + * Initializes @ref. If @flags is zero or PERCPU_REF_ALLOW_REINIT, @ref starts
> > > + * in percpu mode with a refcount of 1; analagous to atomic_long_set(ref, 1).
> > > + * See the definitions of PERCPU_REF_INIT_* flags for flag behaviors.
> >
> > Yeah. Prior we had both PERCPU_REF_INIT_ATOMIC and PERCPU_REF_INIT_DEAD
> > with the latter implying the former. So 0 meant percpu and the others
> > meant atomic. With PERCPU_REF_ALLOW_REINIT, it's probably easier to
> > understand by saying if neither PERCPU_REF_INIT_ATOMIC or
> > PERCPU_REF_INIT_DEAD is set, it starts out in percpu mode which is
> > mentioned in the comments where the flags are defined. It's not great
> > having implied flags, but it's worked so far.
> >
> > Also, it's not quite analagous to atomic_long_set(ref, 1) as there is a
> > bias to prevent prematurely hitting 0.
> >
> > I can take this and massage the wording a bit.
>
> Hello Ira! Hello Dennis!
>
> Yeah, I'd simple say that it starts in the percpu mode, except the case when
> PERCPU_REF_INIT_ATOMIC is set, then (atomic mode, 1) and
> PERCPU_REF_INIT_DEAD is set, then (atomic mode, 0).
>
> PERCPU_REF_ALLOW_REINIT actually doesn't affect the initial state.
>

Thanks for the clarification. Dennis let me know if you want me to resubmit
the patch.

Thanks!
Ira

\
 
 \ /
  Last update: 2020-02-23 15:33    [W:0.119 / U:0.848 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site