[PATCH RESEND v2 00/19] random: Resolve circular include dependency and include <linux/percpu.h>

[PATCH RESEND v2 00/19] random: Resolve circular include dependency and include <linux/percpu.h>

[Uros Bizjak]

Resent due to missing linux-kernel@ mailing list inclusion.

There were several attempts to resolve circular include dependency
after the addition of percpu.h: 1c9df907da83 ("random: fix circular
include dependency on arm64 after addition of percpu.h"), c0842fbc1b18
("random32: move the pseudo-random 32-bit definitions to prandom.h") and
finally d9f29deb7fe8 ("prandom: Remove unused include") that completely
removes the inclusion of <linux/percpu.h>.

Due to legacy reasons, <linux/random.h> includes <linux/prandom.h>, but
with the commit entry remark:

--quote--
A further cleanup step would be to remove this from <linux/random.h>
entirely, and make people who use the prandom infrastructure include
just the new header file.  That's a bit of a churn patch, but grepping
for "prandom_" and "next_pseudo_random32" "struct rnd_state" should
catch most users.

But it turns out that that nice cleanup step is fairly painful, because
a _lot_ of code currently seems to depend on the implicit include of
<linux/random.h>, which can currently come in a lot of ways, including
such fairly core headfers as <linux/net.h>.

So the "nice cleanup" part may or may never happen.
--/quote--

We would like to include <linux/percpu.h> in <linux/prandom.h>.
In [1] we would like to repurpose __percpu tag as a named address space
qualifier, where __percpu macro uses defines from <linux/percpu.h>.

The major roadblock to inclusion of <linux/percpu.h> is the above
mentioned legacy inclusion of <linux/prandom.h> in <linux/random.h> that
causes circular include dependency that prevents <linux/percpu.h>
inclusion.

This patch series is the "nice cleanup" part that:

a) Substitutes the inclusion of <linux/random.h> with the
inclusion of <linux/prandom.h> where needed (patches 1 - 17).

b) Removes legacy inclusion of <linux/prandom.h> from
<linux/random.h> (patch 18).

c) Includes <linux/percpu.h> in <linux/prandom.h> (patch 19).

The whole series was tested by compiling the kernel for x86_64 allconfig
and some popular architectures, namely arm64 defconfig, powerpc defconfig
and loongarch defconfig.

[1] https://lore.kernel.org/lkml/20240812115945.484051-4-ubizjak@gmail.com/

Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
---
v2: - Reword commit messages to mention the removal of legacy inclusion
    of <linux/prandom.h> from <linux/random.h>
    - Add missing substitution in crypto/testmgr.c
    (reported by kernel test robot)
    - Add Acked-by:.

Uros Bizjak (19):
  x86/kaslr: Include <linux/prandom.h> instead of <linux/random.h>
  crypto: testmgr: Include <linux/prandom.h> instead of <linux/random.h>
  drm/i915/selftests: Include <linux/prandom.h> instead of
    <linux/random.h>
  drm/lib: Include <linux/prandom.h> instead of <linux/random.h>
  media: vivid: Include <linux/prandom.h> in vivid-vid-cap.c
  mtd: tests: Include <linux/prandom.h> instead of <linux/random.h>
  fscrypt: Include <linux/once.h> in fs/crypto/keyring.c
  scsi: libfcoe: Include <linux/prandom.h> instead of <linux/random.h>
  bpf: Include <linux/prandom.h> instead of <linux/random.h>
  lib/interval_tree_test.c: Include <linux/prandom.h> instead of
    <linux/random.h>
  kunit: string-stream-test: Include <linux/prandom.h> instead of
    <linux/random.h>
  random32: Include <linux/prandom.h> instead of <linux/random.h>
  lib/rbtree-test: Include <linux/prandom.h> instead of <linux/random.h>
  bpf/tests: Include <linux/prandom.h> instead of <linux/random.h>
  lib/test_parman: Include <linux/prandom.h> instead of <linux/random.h>
  lib/test_scanf: Include <linux/prandom.h> instead of <linux/random.h>
  netem: Include <linux/prandom.h> in sch_netem.c
  random: Do not include <linux/prandom.h> in <linux/random.h>
  prandom: Include <linux/percpu.h> in <linux/prandom.h>

 arch/x86/mm/kaslr.c                              | 2 +-
 crypto/testmgr.c                                 | 2 +-
 drivers/gpu/drm/i915/selftests/i915_gem.c        | 2 +-
 drivers/gpu/drm/i915/selftests/i915_random.h     | 2 +-
 drivers/gpu/drm/i915/selftests/scatterlist.c     | 2 +-
 drivers/gpu/drm/lib/drm_random.h                 | 2 +-
 drivers/media/test-drivers/vivid/vivid-vid-cap.c | 1 +
 drivers/mtd/tests/oobtest.c                      | 2 +-
 drivers/mtd/tests/pagetest.c                     | 2 +-
 drivers/mtd/tests/subpagetest.c                  | 2 +-
 fs/crypto/keyring.c                              | 1 +
 include/linux/prandom.h                          | 1 +
 include/linux/random.h                           | 7 -------
 include/scsi/libfcoe.h                           | 2 +-
 kernel/bpf/core.c                                | 2 +-
 lib/interval_tree_test.c                         | 2 +-
 lib/kunit/string-stream-test.c                   | 1 +
 lib/random32.c                                   | 2 +-
 lib/rbtree_test.c                                | 2 +-
 lib/test_bpf.c                                   | 2 +-
 lib/test_parman.c                                | 2 +-
 lib/test_scanf.c                                 | 2 +-
 net/sched/sch_netem.c                            | 1 +
 23 files changed, 22 insertions(+), 24 deletions(-)

-- 
2.46.0

[PATCH RESEND v2 01/19] x86/kaslr: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
 arch/x86/mm/kaslr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 230f1dee4f09..e17e6e27b7ec 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -22,7 +22,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/memblock.h>
 #include <linux/pgtable.h>
 
-- 
2.46.0

[PATCH RESEND v2 02/19] crypto: testmgr: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
---
 crypto/testmgr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index f02cb075bd68..eeb7edd99a93 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c
@@ -23,7 +23,7 @@
 #include <linux/fips.h>
 #include <linux/module.h>
 #include <linux/once.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/string.h>
-- 
2.46.0

Re: [PATCH RESEND v2 02/19] crypto: testmgr: Include <linux/prandom.h> instead of <linux/random.h>

[Herbert Xu]

Uros Bizjak <ubizjak@gmail.com> wrote:
> Substitute the inclusion of <linux/random.h> header with
> <linux/prandom.h> to allow the removal of legacy inclusion
> of <linux/prandom.h> from <linux/random.h>.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: "David S. Miller" <davem@davemloft.net>
> ---
> crypto/testmgr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[PATCH RESEND v2 03/19] drm/i915/selftests: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/i915/selftests/i915_gem.c    | 2 +-
 drivers/gpu/drm/i915/selftests/i915_random.h | 2 +-
 drivers/gpu/drm/i915/selftests/scatterlist.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem.c b/drivers/gpu/drm/i915/selftests/i915_gem.c
index 61da4ed9d521..0727492576be 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem.c
@@ -4,7 +4,7 @@
  * Copyright © 2018 Intel Corporation
  */
 
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "gem/i915_gem_internal.h"
 #include "gem/i915_gem_pm.h"
diff --git a/drivers/gpu/drm/i915/selftests/i915_random.h b/drivers/gpu/drm/i915/selftests/i915_random.h
index 05364eca20f7..70330a2e80f2 100644
--- a/drivers/gpu/drm/i915/selftests/i915_random.h
+++ b/drivers/gpu/drm/i915/selftests/i915_random.h
@@ -26,7 +26,7 @@
 #define __I915_SELFTESTS_RANDOM_H__
 
 #include <linux/math64.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "../i915_selftest.h"
 
diff --git a/drivers/gpu/drm/i915/selftests/scatterlist.c b/drivers/gpu/drm/i915/selftests/scatterlist.c
index 805c4bfb85fe..7e59591bbed6 100644
--- a/drivers/gpu/drm/i915/selftests/scatterlist.c
+++ b/drivers/gpu/drm/i915/selftests/scatterlist.c
@@ -22,7 +22,7 @@
  */
 
 #include <linux/prime_numbers.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "i915_selftest.h"
 #include "i915_utils.h"
-- 
2.46.0

[PATCH RESEND v2 04/19] drm/lib: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
---
 drivers/gpu/drm/lib/drm_random.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/lib/drm_random.h b/drivers/gpu/drm/lib/drm_random.h
index 5543bf0474bc..9f827260a89d 100644
--- a/drivers/gpu/drm/lib/drm_random.h
+++ b/drivers/gpu/drm/lib/drm_random.h
@@ -6,7 +6,7 @@
  * be transposed to lib/ at the earliest convenience.
  */
 
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #define DRM_RND_STATE_INITIALIZER(seed__) ({				\
 	struct rnd_state state__;					\
-- 
2.46.0

[PATCH RESEND v2 05/19] media: vivid: Include <linux/prandom.h> in vivid-vid-cap.c

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: linux-media@vger.kernel.org
---
 drivers/media/test-drivers/vivid/vivid-vid-cap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/test-drivers/vivid/vivid-vid-cap.c b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
index 69620e0a35a0..184460eb356e 100644
--- a/drivers/media/test-drivers/vivid/vivid-vid-cap.c
+++ b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
@@ -10,6 +10,7 @@
 #include <linux/sched.h>
 #include <linux/vmalloc.h>
 #include <linux/videodev2.h>
+#include <linux/prandom.h>
 #include <linux/v4l2-dv-timings.h>
 #include <media/v4l2-common.h>
 #include <media/v4l2-event.h>
-- 
2.46.0

Re: [PATCH RESEND v2 05/19] media: vivid: Include <linux/prandom.h> in vivid-vid-cap.c

[Hans Verkuil]

On 09/09/2024 09:53, Uros Bizjak wrote:
> Substitute the inclusion of <linux/random.h> header with
> <linux/prandom.h> to allow the removal of legacy inclusion
> of <linux/prandom.h> from <linux/random.h>.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>

Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Regards,

	Hans

> Cc: Hans Verkuil <hverkuil@xs4all.nl>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: linux-media@vger.kernel.org
> ---
>  drivers/media/test-drivers/vivid/vivid-vid-cap.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/media/test-drivers/vivid/vivid-vid-cap.c b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
> index 69620e0a35a0..184460eb356e 100644
> --- a/drivers/media/test-drivers/vivid/vivid-vid-cap.c
> +++ b/drivers/media/test-drivers/vivid/vivid-vid-cap.c
> @@ -10,6 +10,7 @@
>  #include <linux/sched.h>
>  #include <linux/vmalloc.h>
>  #include <linux/videodev2.h>
> +#include <linux/prandom.h>
>  #include <linux/v4l2-dv-timings.h>
>  #include <media/v4l2-common.h>
>  #include <media/v4l2-event.h>

[PATCH RESEND v2 06/19] mtd: tests: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
---
 drivers/mtd/tests/oobtest.c     | 2 +-
 drivers/mtd/tests/pagetest.c    | 2 +-
 drivers/mtd/tests/subpagetest.c | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/tests/oobtest.c b/drivers/mtd/tests/oobtest.c
index 13fed398937e..e1ee68f8b8f8 100644
--- a/drivers/mtd/tests/oobtest.c
+++ b/drivers/mtd/tests/oobtest.c
@@ -17,7 +17,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "mtd_test.h"
 
diff --git a/drivers/mtd/tests/pagetest.c b/drivers/mtd/tests/pagetest.c
index 8eb40b6e6dfa..6878700d2fc0 100644
--- a/drivers/mtd/tests/pagetest.c
+++ b/drivers/mtd/tests/pagetest.c
@@ -17,7 +17,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "mtd_test.h"
 
diff --git a/drivers/mtd/tests/subpagetest.c b/drivers/mtd/tests/subpagetest.c
index 05250a080139..f34bbf033c4d 100644
--- a/drivers/mtd/tests/subpagetest.c
+++ b/drivers/mtd/tests/subpagetest.c
@@ -15,7 +15,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 
 #include "mtd_test.h"
 
-- 
2.46.0

Re: [PATCH RESEND v2 06/19] mtd: tests: Include <linux/prandom.h> instead of <linux/random.h>

[Miquel Raynal]

Hi Uros,

ubizjak@gmail.com wrote on Mon,  9 Sep 2024 09:53:49 +0200:

> Substitute the inclusion of <linux/random.h> header with
> <linux/prandom.h> to allow the removal of legacy inclusion
> of <linux/prandom.h> from <linux/random.h>.

Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>

> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> Cc: Richard Weinberger <richard@nod.at>
> Cc: Vignesh Raghavendra <vigneshr@ti.com>

Miquèl

[PATCH RESEND v2 07/19] fscrypt: Include <linux/once.h> in fs/crypto/keyring.c

[Uros Bizjak]

Include <linux/once.h> header to allow the removal of legacy
inclusion of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: "Theodore Y. Ts'o" <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
---
v2: Include <linux/once.h> instead of <linux/prandom.h>
---
 fs/crypto/keyring.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 6681a71625f0..82fcc5683649 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -22,6 +22,7 @@
 #include <crypto/skcipher.h>
 #include <linux/key-type.h>
 #include <linux/random.h>
+#include <linux/once.h>
 #include <linux/seq_file.h>
 
 #include "fscrypt_private.h"
-- 
2.46.0

Re: [PATCH RESEND v2 07/19] fscrypt: Include <linux/once.h> in fs/crypto/keyring.c

[Eric Biggers]

On Mon, Sep 09, 2024 at 09:53:50AM +0200, Uros Bizjak wrote:
> Include <linux/once.h> header to allow the removal of legacy
> inclusion of <linux/prandom.h> from <linux/random.h>.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Eric Biggers <ebiggers@kernel.org>
> Cc: "Theodore Y. Ts'o" <tytso@mit.edu>
> Cc: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
> v2: Include <linux/once.h> instead of <linux/prandom.h>
> ---
>  fs/crypto/keyring.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
> index 6681a71625f0..82fcc5683649 100644
> --- a/fs/crypto/keyring.c
> +++ b/fs/crypto/keyring.c
> @@ -22,6 +22,7 @@
>  #include <crypto/skcipher.h>
>  #include <linux/key-type.h>
>  #include <linux/random.h>
> +#include <linux/once.h>
>  #include <linux/seq_file.h>
>  
>  #include "fscrypt_private.h"

Acked-by: Eric Biggers <ebiggers@google.com>

- Eric

[PATCH RESEND v2 08/19] scsi: libfcoe: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
---
 include/scsi/libfcoe.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
index 3c5899290aed..6616348e59b9 100644
--- a/include/scsi/libfcoe.h
+++ b/include/scsi/libfcoe.h
@@ -15,7 +15,7 @@
 #include <linux/skbuff.h>
 #include <linux/workqueue.h>
 #include <linux/local_lock.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <scsi/fc/fc_fcoe.h>
 #include <scsi/libfc.h>
 #include <scsi/fcoe_sysfs.h>
-- 
2.46.0

Re: [PATCH RESEND v2 08/19] scsi: libfcoe: Include <linux/prandom.h> instead of <linux/random.h>

[Bart Van Assche]

On 9/9/24 12:53 AM, Uros Bizjak wrote:
> Substitute the inclusion of <linux/random.h> header with
> <linux/prandom.h> to allow the removal of legacy inclusion
> of <linux/prandom.h> from <linux/random.h>.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
> Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
> ---
>   include/scsi/libfcoe.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
> index 3c5899290aed..6616348e59b9 100644
> --- a/include/scsi/libfcoe.h
> +++ b/include/scsi/libfcoe.h
> @@ -15,7 +15,7 @@
>   #include <linux/skbuff.h>
>   #include <linux/workqueue.h>
>   #include <linux/local_lock.h>
> -#include <linux/random.h>
> +#include <linux/prandom.h>
>   #include <scsi/fc/fc_fcoe.h>
>   #include <scsi/libfc.h>
>   #include <scsi/fcoe_sysfs.h>

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

[PATCH RESEND v2 09/19] bpf: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
---
 kernel/bpf/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7ee62e38faf0..3f0d1eb7f5b0 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -21,7 +21,7 @@
 #include <linux/filter.h>
 #include <linux/skbuff.h>
 #include <linux/vmalloc.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/bpf.h>
 #include <linux/btf.h>
 #include <linux/objtool.h>
-- 
2.46.0

[PATCH RESEND v2 10/19] lib/interval_tree_test.c: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 lib/interval_tree_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/interval_tree_test.c b/lib/interval_tree_test.c
index f37f4d44faa9..837064b83a6c 100644
--- a/lib/interval_tree_test.c
+++ b/lib/interval_tree_test.c
@@ -2,7 +2,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/interval_tree.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/slab.h>
 #include <asm/timex.h>
 
-- 
2.46.0

[PATCH RESEND v2 11/19] kunit: string-stream-test: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Rae Moar <rmoar@google.com>
---
 lib/kunit/string-stream-test.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/kunit/string-stream-test.c b/lib/kunit/string-stream-test.c
index 7511442ea98f..7734e33156f9 100644
--- a/lib/kunit/string-stream-test.c
+++ b/lib/kunit/string-stream-test.c
@@ -9,6 +9,7 @@
 #include <kunit/static_stub.h>
 #include <kunit/test.h>
 #include <linux/ktime.h>
+#include <linux/prandom.h>
 #include <linux/slab.h>
 #include <linux/timekeeping.h>
 
-- 
2.46.0

[PATCH RESEND v2 12/19] random32: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
---
 lib/random32.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/random32.c b/lib/random32.c
index 32060b852668..31fc2ca68856 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -36,7 +36,7 @@
 #include <linux/percpu.h>
 #include <linux/export.h>
 #include <linux/jiffies.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/sched.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
-- 
2.46.0

[PATCH RESEND v2 13/19] lib/rbtree-test: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 lib/rbtree_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
index 41ae3c7570d3..8655a76d29a1 100644
--- a/lib/rbtree_test.c
+++ b/lib/rbtree_test.c
@@ -2,7 +2,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/rbtree_augmented.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/slab.h>
 #include <asm/timex.h>
 
-- 
2.46.0

[PATCH RESEND v2 14/19] bpf/tests: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
---
 lib/test_bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index ca4b0eea81a2..eb4a1915e4d2 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -14,7 +14,7 @@
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/if_vlan.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/highmem.h>
 #include <linux/sched.h>
 
-- 
2.46.0

[PATCH RESEND v2 15/19] lib/test_parman: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Pirko <jiri@resnulli.us>
---
 lib/test_parman.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_parman.c b/lib/test_parman.c
index 35e32243693c..f9b97426a337 100644
--- a/lib/test_parman.c
+++ b/lib/test_parman.c
@@ -39,7 +39,7 @@
 #include <linux/slab.h>
 #include <linux/bitops.h>
 #include <linux/err.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/parman.h>
 
 #define TEST_PARMAN_PRIO_SHIFT 7 /* defines number of prios for testing */
-- 
2.46.0

[PATCH RESEND v2 16/19] lib/test_scanf: Include <linux/prandom.h> instead of <linux/random.h>

[Uros Bizjak]

Substitute the inclusion of <linux/random.h> header with
<linux/prandom.h> to allow the removal of legacy inclusion
of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 lib/test_scanf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/test_scanf.c b/lib/test_scanf.c
index 7257b1768545..44f8508c9d88 100644
--- a/lib/test_scanf.c
+++ b/lib/test_scanf.c
@@ -11,7 +11,7 @@
 #include <linux/module.h>
 #include <linux/overflow.h>
 #include <linux/printk.h>
-#include <linux/random.h>
+#include <linux/prandom.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 
-- 
2.46.0

Re: [PATCH RESEND v2 16/19] lib/test_scanf: Include <linux/prandom.h> instead of <linux/random.h>

[Petr Mladek]

On Mon 2024-09-09 09:53:59, Uros Bizjak wrote:
> Substitute the inclusion of <linux/random.h> header with
> <linux/prandom.h> to allow the removal of legacy inclusion
> of <linux/prandom.h> from <linux/random.h>.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>

I have just acked v1 and missed that there already is v2.
Just for record:

Acked-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

[PATCH RESEND v2 17/19] netem: Include <linux/prandom.h> in sch_netem.c

[Uros Bizjak]

Include <linux/prandom.h> header to allow the removal of legacy
inclusion of <linux/prandom.h> from <linux/random.h>.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
---
 net/sched/sch_netem.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 0f8d581438c3..2d919f590772 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -17,6 +17,7 @@
 #include <linux/errno.h>
 #include <linux/skbuff.h>
 #include <linux/vmalloc.h>
+#include <linux/prandom.h>
 #include <linux/rtnetlink.h>
 #include <linux/reciprocal_div.h>
 #include <linux/rbtree.h>
-- 
2.46.0

[PATCH RESEND v2 18/19] random: Do not include <linux/prandom.h> in <linux/random.h>

[Uros Bizjak]

Files that use prandom infrastructure are now converted to
use <linux/prandom.h> header instead of <linux/random.h>.
Remove the legacy inclusion of <linux/prandom.h> from
<linux/random.h>.

This is the "nice cleanup" part, wished in c0842fbc1b18.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Fixes: c0842fbc1b18 ("random32: move the pseudo-random 32-bit definitions to prandom.h")
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/linux/random.h | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/include/linux/random.h b/include/linux/random.h
index b0a940af4fff..333cecfca93f 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -145,13 +145,6 @@ declare_get_random_var_wait(u64, u32)
 declare_get_random_var_wait(long, unsigned long)
 #undef declare_get_random_var
 
-/*
- * This is designed to be standalone for just prandom
- * users, but for now we include it from <linux/random.h>
- * for legacy reasons.
- */
-#include <linux/prandom.h>
-
 #ifdef CONFIG_SMP
 int random_prepare_cpu(unsigned int cpu);
 int random_online_cpu(unsigned int cpu);
-- 
2.46.0

[PATCH RESEND v2 19/19] prandom: Include <linux/percpu.h> in <linux/prandom.h>

[Uros Bizjak]

<linux/percpu.h> include was removed from <linux/prandom.h>
in d9f29deb7fe8 ("prandom: Remove unused include") because
this inclusion broke arm64 due to a circular dependency
on include files.

__percpu tag is defined in include/linux/compiler_types.h, so there
is currently no direct need for the inclusion of <linux/percpu.h>.
However, in [1] we would like to repurpose __percpu tag as a named
address space qualifier, where __percpu macro uses defines from
<linux/percpu.h>.

The circular dependency was removed in xxxxxxxxxxxx ("random: Do not
include <linux/prandom.h> in <linux/random.h>") and it cleared
the path for the inclusion of <linux/percpu.h> in <linux/prandom.h>.

This patch is basically a revert of d9f29deb7fe8
("prandom: Remove unused include").

[1] https://lore.kernel.org/lkml/20240812115945.484051-4-ubizjak@gmail.com/

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
---
 include/linux/prandom.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/prandom.h b/include/linux/prandom.h
index f7f1e5251c67..f2ed5b72b3d6 100644
--- a/include/linux/prandom.h
+++ b/include/linux/prandom.h
@@ -10,6 +10,7 @@
 
 #include <linux/types.h>
 #include <linux/once.h>
+#include <linux/percpu.h>
 #include <linux/random.h>
 
 struct rnd_state {
-- 
2.46.0

Re: [PATCH RESEND v2 00/19] random: Resolve circular include dependency and include <linux/percpu.h>

[Jason A. Donenfeld]

Hi Uros,

On Mon, Sep 09, 2024 at 09:53:43AM +0200, Uros Bizjak wrote:
> a) Substitutes the inclusion of <linux/random.h> with the
> inclusion of <linux/prandom.h> where needed (patches 1 - 17).
> 
> b) Removes legacy inclusion of <linux/prandom.h> from
> <linux/random.h> (patch 18).
> 
> c) Includes <linux/percpu.h> in <linux/prandom.h> (patch 19).
 
Thanks for doing this. That seems like a fine initiative to me. (I'm
also curious about the future percpu changes you've got planned.)

Tree-wise, were you expecting me to take this through random.git? And if
so, what timeframe did you have in mind? For 6.12 next week (can you
poke folks for acks in time?), or punt it for 6.13? Or did you have a
different tree in mind for treewide changes (in which case, I'll send
you an ack for the [p]random.h changes).

Regards,
Jason

Re: [PATCH RESEND v2 00/19] random: Resolve circular include dependency and include <linux/percpu.h>

[Uros Bizjak]

On Mon, Sep 9, 2024 at 5:57 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:

> On Mon, Sep 09, 2024 at 09:53:43AM +0200, Uros Bizjak wrote:
> > a) Substitutes the inclusion of <linux/random.h> with the
> > inclusion of <linux/prandom.h> where needed (patches 1 - 17).
> >
> > b) Removes legacy inclusion of <linux/prandom.h> from
> > <linux/random.h> (patch 18).
> >
> > c) Includes <linux/percpu.h> in <linux/prandom.h> (patch 19).
>
> Thanks for doing this. That seems like a fine initiative to me. (I'm
> also curious about the future percpu changes you've got planned.)

As explained in the cover letter, recent GCCs are able to track
address space of variables in percpu address space from the
declaration to its usage site. There are certain rules regarding casts
of variables and their pointers (when this named address space is not
considered a subspace of the generic address space), so it is possible
to create much more effective checks for cast-from-as type casts than
what sparse can achieve.

Besides GCC, clang can define various named address space via
address_space attribute:

--cut here--
#define __as(N) __attribute__((address_space(N)))

void *foo(void __as(1) *x) { return x; }         // error

void *bar(void __as(1) *x) { return (void *)x; } // fine
--cut here--

When compiling this, the compiler returns:

clang-as.c:3:37: error: returning '__as(1) void *' from a function
with result type 'void *' changes address space of pointer

Although clang currently errors out when __seg_gs and __seg_fs named
address space designators are used, we can explore its named address
spaces functionality to implement percpu checks for all targets. The
percpu address space checks patchset, referred to in the cover letter,
also supports this functionality when per_cpu_qual is defined to
__attribute__((address_space(N))).

Perhaps we can use different address spaces to also handle __user,
__iomem and __rcu address spaces. This way the compiler will be able
to handle address space checks instead of sparse.

> Tree-wise, were you expecting me to take this through random.git? And if
> so, what timeframe did you have in mind? For 6.12 next week (can you
> poke folks for acks in time?), or punt it for 6.13? Or did you have a
> different tree in mind for treewide changes (in which case, I'll send
> you an ack for the [p]random.h changes).

I think that the best approach is to target this patchset for linux
6.13 via random.git tree. I will prepare a v3 after 6.12rc1, so when
committed to random.git, the patchset will be able to spend some time
in linux-next. This way, there will be plenty of time for CI robots to
do additional checks also for some less popular targets (although
individual patches are dead simple, removing these kinds of "legacy"
includes can be tricky), and I will also be able to collect Acked-by:s
in the meantime.

While the patchset is an improvement by itself, its inclusion is not
time sensitive. The follow up percpu named address checking
functionality requires a very recent feature (__typeof_unqual__
keyword), which is only supported in recent compilers (gcc-14 and
clang-20). Besides compiler support, sparse doesn't know about
__typeof_unqual__, resulting in broken type tracing and hundreds of
sparse errors with C=1 due to unknown keyword.

So, I think we are not in a hurry and can take the slow and safe path.

Thanks and best regards,
Uros.

Re: [PATCH RESEND v2 00/19] random: Resolve circular include dependency and include <linux/percpu.h>

[Jason A. Donenfeld]

Hi Uros,

On Mon, Sep 09, 2024 at 09:30:06PM +0200, Uros Bizjak wrote:
> Besides GCC, clang can define various named address space via
> address_space attribute:
> 
> --cut here--
> #define __as(N) __attribute__((address_space(N)))
> 
> void *foo(void __as(1) *x) { return x; }         // error
> 
> void *bar(void __as(1) *x) { return (void *)x; } // fine
> --cut here--
> 
> When compiling this, the compiler returns:
> 
> clang-as.c:3:37: error: returning '__as(1) void *' from a function
> with result type 'void *' changes address space of pointer

Super cool. Looking forward to having it all wired up and the bugs we'll
find with it. 

> I think that the best approach is to target this patchset for linux
> 6.13 via random.git tree. I will prepare a v3 after 6.12rc1, so when
> committed to random.git, the patchset will be able to spend some time
> in linux-next. This way, there will be plenty of time for CI robots to
> do additional checks also for some less popular targets (although
> individual patches are dead simple, removing these kinds of "legacy"
> includes can be tricky), and I will also be able to collect Acked-by:s
> in the meantime.
> 
> While the patchset is an improvement by itself, its inclusion is not
> time sensitive. The follow up percpu named address checking
> functionality requires a very recent feature (__typeof_unqual__
> keyword), which is only supported in recent compilers (gcc-14 and
> clang-20). Besides compiler support, sparse doesn't know about
> __typeof_unqual__, resulting in broken type tracing and hundreds of
> sparse errors with C=1 due to unknown keyword.
> 
> So, I think we are not in a hurry and can take the slow and safe path.

Okay, sure, that sounds good to me. I'll keep my eyes open for v3
in a few weeks then.

Jason