Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1595549

Re: [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to refcount_t

Show all headers | View raw

On Wed, Mar 8, 2017 at 7:50 AM, Christoph Hellwig <hch@infradead.org> wrote:
>> -     ASSERT(atomic_read(&ticket->t_ref) > 0);
>> -     atomic_inc(&ticket->t_ref);
>> +     ASSERT(refcount_read(&ticket->t_ref) > 0);
>> +     refcount_inc(&ticket->t_ref);
>
> With strict refcount semantics refcount_inc should check that
> the count is larger than 0, otherwise we'd need to use
> recount_inc_not_zero or whatever you're going to call it.
>
> Is that something the recount code does / could do?

Yes, refcount_inc() will not increment from 0 and WARNs. It looks like
xfs's ASSERT is also a warn (though with XFS-specific formatting), so
perhaps the ASSERT could be dropped? IIUC, Elena's approach to these
changes was to be conservative about removing the existing checks.

-Kees

-- 
Kees Cook
Pixel Security

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/5] fs, xfs refcount conversions Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 10:00 +0100
  [PATCH 5/5] fs, xfs: convert xfs_rui_log_item.rui_refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 10:00 +0100
  [PATCH 1/5] fs, xfs: convert xfs_bui_log_item.bui_refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 10:00 +0100
  [PATCH 2/5] fs, xfs: convert xfs_efi_log_item.efi_refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 10:00 +0100
  [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 12:40 +0100
    Re: [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to  refcount_t Christoph Hellwig <hch@infradead.org> - 2017-03-08 17:00 +0100
      Re: [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to refcount_t Kees Cook <keescook@chromium.org> - 2017-03-08 23:10 +0100
        RE: [PATCH 3/5] fs, xfs: convert xlog_ticket.t_ref from atomic_t to  refcount_t "Reshetova, Elena" <elena.reshetova@intel.com> - 2017-03-09 08:00 +0100
  [PATCH 4/5] fs, xfs: convert xfs_cui_log_item.cui_refcount from atomic_t to refcount_t Elena Reshetova <elena.reshetova@intel.com> - 2017-03-08 15:40 +0100

csiph-web