On Sat, Feb 16, 2008 at 08:19:58AM -0800, Paul E. McKenney wrote:
> On Sat, Feb 16, 2008 at 10:47:23AM +0200, Adrian Bunk wrote:
> > On Mon, Jan 28, 2008 at 04:25:00AM -0800, Paul E. McKenney wrote:
> > > Hello!
> > >
> > > The list_for_each_entry_rcu() primitive should be used instead of
> > > list_for_each_rcu(), as the former is easier to use and provides
> > > better type safety. This patch therefore adds list_for_each_rcu()
> > > to the Documentation/feature-removal-schedule.txt file (for mid-2008)
> > > and marks its comment header deprecated.
> > >
> > > Signed-off-by: Paul E. McKenney <[EMAIL PROTECTED]>
> > > ---
> > >
> > > Documentation/feature-removal-schedule.txt | 10 ++++++++++
> > > include/linux/list.h | 5 ++++-
> > > 2 files changed, 14 insertions(+), 1 deletion(-)
> > >
> > > diff -urpNa -X dontdiff
> > > linux-2.6.24/Documentation/feature-removal-schedule.txt
> > > linux-2.6.24-dep-lfeRCU/Documentation/feature-removal-schedule.txt
> > > --- linux-2.6.24/Documentation/feature-removal-schedule.txt
> > > 2008-01-24 14:58:37.000000000 -0800
> > > +++ linux-2.6.24-dep-lfeRCU/Documentation/feature-removal-schedule.txt
> > > 2008-01-28 04:00:49.000000000 -0800
> > > @@ -333,3 +333,13 @@ Why: This driver has been marked obsolet
> > > Who: Stephen Hemminger <[EMAIL PROTECTED]>
> > >
> > > ---------------------------
> > > +
> > > +What: list_for_each_rcu() primitive
> > > +When: July 2008
> > > +Files: include/linux/list.h
> > > +Why: The list_for_each_entry_rcu() primitive should be used instead,
> > > + as it is less error-prone and provides better type safety.
> > > +Who: Paul E. McKenney <[EMAIL PROTECTED]>
> > >...
> >
> > Declaring something as deprecated doesn't automatically convert the
> > in-kernel users.
>
> Understood.
>
> > And once there are no in-kernel users left you can kill it immediately.
>
> Hmmm... What is the purpose of Documentation/feature-removal-schedule.txt
> in that case?
I don't see any reason for not userspace visible things to be listed in
feature-removal-schedule.txt (with module names counted as being
userspace visible) - they can be removed as soon as the last in-kernel
user is gone.
> > The only working way for getting rid of list_for_each_rcu() is:
> > - send patches for all in-kernel usages to the maintainers of the code
> > in question now
>
> That has happened at least once.
Resend the patches (with a Cc to linux-kernel) until all of them got
picked up...
> > - once all of these patches have entered Linus' tree (which might not
> > be before the 2.6.26 merge window) you can remove list_for_each_rcu()
>
> So your approach would be to mark the macro obsolete to prevent additional
> uses in the meantime?
That can't harm.
But realistically, the only way to prevent additional uses is to
completely remove it...
> Thanx, Paul
cu
Adrian
--
An architecture specific patch that breaks the one architecture it
touches at the first file being compiled is even for kernel standards
unusually bad...
Me about a recent commit in Linus' tree
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