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Groups > linux.kernel > #1522417

Re: [RFC][PATCH 5/7] kref: Implement kref_put_lock()

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [RFC][PATCH 5/7] kref: Implement kref_put_lock()
Date 2016-11-15 09:00 +0100
Message-ID <sDGOR-22f-5@gated-at.bofh.it> (permalink)
References <sDtyh-1DM-5@gated-at.bofh.it> <sDtyi-1DM-21@gated-at.bofh.it> <sDwcN-3pr-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Mon, Nov 14, 2016 at 12:35:48PM -0800, Kees Cook wrote:
> On Mon, Nov 14, 2016 at 9:39 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > Because home-rolling your own is _awesome_, stop doing it. Provide
> > kref_put_lock(), just like kref_put_mutex() but for a spinlock.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > ---
> >  include/linux/kref.h |   21 +++++++++++++++------
> >  net/sunrpc/svcauth.c |   15 ++++++++++-----
> >  2 files changed, 25 insertions(+), 11 deletions(-)
> >
> > --- a/include/linux/kref.h
> > +++ b/include/linux/kref.h
> > @@ -86,12 +86,21 @@ static inline int kref_put_mutex(struct
> >                                  struct mutex *lock)
> >  {
> >         WARN_ON(release == NULL);
> 
> This WARN_ON makes sense, yes, though it seems like it should be deal
> with differently. If it's NULL, we'll just Oops when we call release()
> later... Seems like this should saturate the kref or something else
> similar.

So I simply took the pattern from the existing kref_put().

But I like it more in these kref_put_{lock,mutex}() variants, because
someone will need to unlock. If we simply crash/bug without unlock we'll
have broken state the rest of the kernel cannot fix up.

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Thread

[RFC][PATCH 0/7] kref improvements Peter Zijlstra <peterz@infradead.org> - 2016-11-14 18:50 +0100
  [RFC][PATCH 5/7] kref: Implement kref_put_lock() Peter Zijlstra <peterz@infradead.org> - 2016-11-14 18:50 +0100
    Re: [RFC][PATCH 5/7] kref: Implement kref_put_lock() Kees Cook <keescook@chromium.org> - 2016-11-14 21:40 +0100
      Re: [RFC][PATCH 5/7] kref: Implement kref_put_lock() Peter Zijlstra <peterz@infradead.org> - 2016-11-15 09:00 +0100
  [RFC][PATCH 6/7] kref: Avoid more abuse Peter Zijlstra <peterz@infradead.org> - 2016-11-14 18:50 +0100
  [RFC][PATCH 4/7] kref: Use kref_get_unless_zero() more Peter Zijlstra <peterz@infradead.org> - 2016-11-14 18:50 +0100
  [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-14 18:50 +0100
    Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-15 09:50 +0100
      Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-15 10:50 +0100
        Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-15 11:10 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-15 11:50 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-15 14:10 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Kees Cook <keescook@chromium.org> - 2016-11-15 19:10 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-15 20:20 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Kees Cook <keescook@chromium.org> - 2016-11-15 20:30 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-16 09:40 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 10:00 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-16 10:10 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 10:30 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-16 11:20 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Kees Cook <keescook@chromium.org> - 2016-11-16 20:00 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 09:40 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Kees Cook <keescook@chromium.org> - 2016-11-17 21:00 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Kees Cook <keescook@chromium.org> - 2016-11-16 19:50 +0100
    Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-15 13:40 +0100
      Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-15 14:10 +0100
        Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-15 15:20 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 10:30 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-17 10:50 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 11:40 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 11:50 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Greg KH <gregkh@linuxfoundation.org> - 2016-11-17 12:10 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 18:10 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 18:30 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Will Deacon <will.deacon@arm.com> - 2016-11-17 18:10 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-18 09:30 +0100
                Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Will Deacon <will.deacon@arm.com> - 2016-11-18 11:20 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Will Deacon <will.deacon@arm.com> - 2016-11-17 18:10 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-17 18:30 +0100
    RE: [RFC][PATCH 7/7] kref: Implement using refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-18 11:10 +0100
      Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-18 12:40 +0100
        Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Will Deacon <will.deacon@arm.com> - 2016-11-18 18:10 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-18 20:00 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-21 05:10 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Ingo Molnar <mingo@kernel.org> - 2016-11-21 08:50 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-21 09:40 +0100
        Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-21 09:50 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-21 10:10 +0100
            Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Boqun Feng <boqun.feng@gmail.com> - 2016-11-21 10:40 +0100
    RE: [RFC][PATCH 7/7] kref: Implement using refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-18 11:50 +0100
      Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-18 12:00 +0100
        RE: [RFC][PATCH 7/7] kref: Implement using refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-18 18:00 +0100
          Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-18 20:00 +0100
            RE: [RFC][PATCH 7/7] kref: Implement using refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-19 08:20 +0100
              Re: [RFC][PATCH 7/7] kref: Implement using refcount_t Peter Zijlstra <peterz@infradead.org> - 2016-11-19 12:50 +0100
  Re: [RFC][PATCH 2/7] kref: Add kref_read() Christoph Hellwig <hch@infradead.org> - 2016-11-14 19:20 +0100
    Re: [RFC][PATCH 2/7] kref: Add kref_read() Greg KH <gregkh@linuxfoundation.org> - 2016-11-15 08:30 +0100
      Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-15 08:50 +0100
      [PATCH] printk, locking/atomics, kref: Introduce new %pAr and %pAk  format string options for atomic_t and 'struct kref' Ingo Molnar <mingo@kernel.org> - 2016-11-15 09:40 +0100
        [PATCH v2] printk, locking/atomics, kref: Introduce new %pAr and  %pAk format string options for atomic_t and 'struct kref' Ingo Molnar <mingo@kernel.org> - 2016-11-15 09:50 +0100
          Re: [PATCH v2] printk, locking/atomics, kref: Introduce new %pAr and  %pAk format string options for atomic_t and 'struct kref' Peter Zijlstra <peterz@infradead.org> - 2016-11-15 10:30 +0100
            [PATCH v3] printk, locking/atomics, kref: Introduce new %pAa and  %pAk format string options for atomic_t and 'struct kref' Ingo Molnar <mingo@kernel.org> - 2016-11-15 10:50 +0100
          Re: [PATCH v2] printk, locking/atomics, kref: Introduce new %pAr and  %pAk format string options for atomic_t and 'struct kref' kbuild test robot <lkp@intel.com> - 2016-11-15 11:10 +0100
        Re: [PATCH] printk, locking/atomics, kref: Introduce new %pAr and  %pAk format string options for atomic_t and 'struct kref' Linus Torvalds <torvalds@linux-foundation.org> - 2016-11-15 17:50 +0100
          Re: [PATCH] printk, locking/atomics, kref: Introduce new %pAr and  %pAk format string options for atomic_t and 'struct kref' Ingo Molnar <mingo@kernel.org> - 2016-11-16 09:20 +0100
  Re: [RFC][PATCH 0/7] kref improvements Greg KH <gregkh@linuxfoundation.org> - 2016-11-15 08:30 +0100
    Re: [RFC][PATCH 0/7] kref improvements Ingo Molnar <mingo@kernel.org> - 2016-11-15 08:50 +0100
      Re: [RFC][PATCH 0/7] kref improvements Greg KH <gregkh@linuxfoundation.org> - 2016-11-15 16:10 +0100
    Re: [RFC][PATCH 0/7] kref improvements Peter Zijlstra <peterz@infradead.org> - 2016-11-15 08:50 +0100
  Re: [RFC][PATCH 2/7] kref: Add kref_read() Greg KH <gregkh@linuxfoundation.org> - 2016-11-15 08:40 +0100
    Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-15 09:10 +0100
      Re: [RFC][PATCH 2/7] kref: Add kref_read() Kees Cook <keescook@chromium.org> - 2016-11-15 22:00 +0100
        Re: [RFC][PATCH 2/7] kref: Add kref_read() Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 09:30 +0100
          Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-16 11:20 +0100
            Re: [RFC][PATCH 2/7] kref: Add kref_read() Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 11:20 +0100
          Re: [RFC][PATCH 2/7] kref: Add kref_read() Greg KH <gregkh@linuxfoundation.org> - 2016-11-16 11:20 +0100
          Re: [RFC][PATCH 2/7] kref: Add kref_read() Daniel Borkmann <daniel@iogearbox.net> - 2016-11-16 11:20 +0100
        Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-16 11:10 +0100
          Re: [RFC][PATCH 2/7] kref: Add kref_read() Kees Cook <keescook@chromium.org> - 2016-11-16 20:00 +0100
            Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-17 09:40 +0100
              Re: [RFC][PATCH 2/7] kref: Add kref_read() David Windsor <dave@progbits.org> - 2016-11-17 13:50 +0100
                RE: [RFC][PATCH 2/7] kref: Add kref_read() "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-17 15:40 +0100
                Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-17 18:10 +0100
                RE: [RFC][PATCH 2/7] kref: Add kref_read() "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-17 18:10 +0100
                RE: [RFC][PATCH 2/7] kref: Add kref_read() "Reshetova, Elena" <elena.reshetova@intel.com> - 2016-11-17 19:10 +0100
                Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-17 20:20 +0100
                Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-17 20:40 +0100
                Re: [RFC][PATCH 2/7] kref: Add kref_read() Peter Zijlstra <peterz@infradead.org> - 2016-11-17 18:20 +0100
              Re: [RFC][PATCH 2/7] kref: Add kref_read() Kees Cook <keescook@chromium.org> - 2016-11-17 20:40 +0100

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