[GIT,PULL] Scope-based Resource Management for 6.5

  Hi Linus,

Please consider pulling the SBRM infrastructure so that people can start
building upon it. Specifically Greg also wants to start using this soon.

Once this lands, I'll start to trickle in the conversions I've done for
the next release.

Thanks!

---

The following changes since commit 6995e2de6891c724bfeb2db33d7b87775f913ad1:

  Linux 6.4 (2023-06-25 16:29:58 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git tags/core_guards_for_6.5_rc1

for you to fetch changes up to b5ec6fd286dfa466f64cb0e56ed768092d0342ae:

  kbuild: Drop -Wdeclaration-after-statement (2023-06-26 11:14:19 +0200)

----------------------------------------------------------------
Scope-based Resource Management infrastructure

These are the first few patches in the Scope-based Resource Management
series that introduce the infrastructure but not any conversions as of
yet.

Adding the infrastructure now allows multiple people to start using them.

Of note is that Sparse will need some work since it doesn't yet
understand this attribute and might have decl-after-stmt issues -- but I
think that's being worked on.

----------------------------------------------------------------
Peter Zijlstra (4):
      dmaengine: ioat: Free up __cleanup() name
      apparmor: Free up __cleanup() name
      locking: Introduce __cleanup() based infrastructure
      kbuild: Drop -Wdeclaration-after-statement

 Makefile                            |   6 +-
 arch/arm64/kernel/vdso32/Makefile   |   2 -
 drivers/dma/ioat/dma.c              |  12 +--
 include/linux/cleanup.h             | 171 ++++++++++++++++++++++++++++++++++++
 include/linux/compiler-clang.h      |   9 ++
 include/linux/compiler_attributes.h |   6 ++
 include/linux/device.h              |   7 ++
 include/linux/file.h                |   6 ++
 include/linux/irqflags.h            |   7 ++
 include/linux/mutex.h               |   4 +
 include/linux/percpu.h              |   4 +
 include/linux/preempt.h             |   5 ++
 include/linux/rcupdate.h            |   3 +
 include/linux/rwsem.h               |   8 ++
 include/linux/sched/task.h          |   2 +
 include/linux/slab.h                |   3 +
 include/linux/spinlock.h            |  31 +++++++
 include/linux/srcu.h                |   5 ++
 scripts/checkpatch.pl               |   2 +-
 security/apparmor/include/lib.h     |   6 +-
 20 files changed, 282 insertions(+), 17 deletions(-)
 create mode 100644 include/linux/cleanup.h
  

On Mon, 26 Jun 2023 at 05:57, Peter Zijlstra <peterz@infradead.org> wrote:
>
> Please consider pulling the SBRM infrastructure so that people can start
> building upon it. Specifically Greg also wants to start using this soon.
>
> Once this lands, I'll start to trickle in the conversions I've done for
> the next release.

So things are quiet (partly presumably due to July 4th in the US) and
I've mostly emptied my merge window queue, so I've pulled this since I
obviously was happy with the final syntax.

However, let's agree to not really use it for 6.5 yet, and consider it
all purely infrastructure for the next release, and for testing it all
out in linux-next etc.

We should probably also strive to avoid it for bug-fixes that end up
going to stable. I'm sure this will all be backported to stable
eventually, but I'd at least personally be happier if that started
happening only after we actually have some more interaction with this.

I hope - and expect - that the core compiler infrastructure should be
stable due to C++ uses of destructors, but I also note that at least
in the system headers I have, the only use of the __cleanup__
attribute seems to be a very special pthread_cleanup_push() helper,
and some (fairly minimal) glib use in the g_auto*() types.

So this attribute has been around forever, and the low-level
functionality has presumably gotten a lot of testing, but at the same
time it really looks like the C interface is somewhat limited in its
use.

I did do a Debian core search on g_autoptr() use, and in the first ten
pages, most uses seemed to be either comments or tests. But there are
certainly *some* real users too.

Anyway, I did find enough use that I'm not worried, but I'd still like
us to take this somewhat slowly.

Let's *not* treat this as a "W00t! Black Friday at Walmart! Everybody
rush in at once!"

             Linus
  

The pull request you sent on Mon, 26 Jun 2023 14:57:26 +0200:

> git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git tags/core_guards_for_6.5_rc1

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/04f2933d375e3f90d4435b7b518d3065afd1fa25

Thank you!
  

On Tue, Jul 04, 2023 at 02:11:05PM -0700, Linus Torvalds wrote:
> On Mon, 26 Jun 2023 at 05:57, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Please consider pulling the SBRM infrastructure so that people can start
> > building upon it. Specifically Greg also wants to start using this soon.
> >
> > Once this lands, I'll start to trickle in the conversions I've done for
> > the next release.
> 
> So things are quiet (partly presumably due to July 4th in the US) and
> I've mostly emptied my merge window queue, so I've pulled this since I
> obviously was happy with the final syntax.
> 
> However, let's agree to not really use it for 6.5 yet, and consider it
> all purely infrastructure for the next release, and for testing it all
> out in linux-next etc.

Sounds good to me.

> We should probably also strive to avoid it for bug-fixes that end up
> going to stable. I'm sure this will all be backported to stable
> eventually, but I'd at least personally be happier if that started
> happening only after we actually have some more interaction with this.

Yeah, it will probably need to be backported to maybe 6.1.y if some real
bugfix needs it, but for all of the trivial "clean up the error path"
patches that we constantly get, we'll resist that for the stable tree if
they use the cleanup logic.  That might actually be a good thing overall
anyway.

> I hope - and expect - that the core compiler infrastructure should be
> stable due to C++ uses of destructors, but I also note that at least
> in the system headers I have, the only use of the __cleanup__
> attribute seems to be a very special pthread_cleanup_push() helper,
> and some (fairly minimal) glib use in the g_auto*() types.
> 
> So this attribute has been around forever, and the low-level
> functionality has presumably gotten a lot of testing, but at the same
> time it really looks like the C interface is somewhat limited in its
> use.
> 
> I did do a Debian core search on g_autoptr() use, and in the first ten
> pages, most uses seemed to be either comments or tests. But there are
> certainly *some* real users too.

systemd has been using it for a long time so the infrastructure has been
there and should be stable, but I'm sure we will find out if not.

thanks,

greg k-h