[v3,00/19] random: Resolve circular include dependency and include <linux/percpu.h>

Message

Uros Bizjak Sept. 30, 2024, 12:33 p.m. UTC

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/[e-mail]/

Cc: Dave Hansen <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: "H. Peter Anvin" <[e-mail]>
Cc: Jani Nikula <[e-mail]>
Cc: Joonas Lahtinen <[e-mail]>
Cc: Rodrigo Vivi <[e-mail]>
Cc: Tvrtko Ursulin <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Maarten Lankhorst <[e-mail]>
Cc: Maxime Ripard <[e-mail]>
Cc: Thomas Zimmermann <[e-mail]>
Cc: Hans Verkuil <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Miquel Raynal <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: Vignesh Raghavendra <[e-mail]>
Cc: Eric Biggers <[e-mail]>
Cc: "Theodore Y. Ts'o" <[e-mail]>
Cc: Jaegeuk Kim <[e-mail]>
Cc: "Jason A. Donenfeld" <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Hannes Reinecke <[e-mail]>
Cc: "James E.J. Bottomley" <[e-mail]>
Cc: "Martin K. Petersen" <[e-mail]>
Cc: Alexei Starovoitov <[e-mail]>
Cc: Daniel Borkmann <[e-mail]>
Cc: John Fastabend <[e-mail]>
Cc: Andrii Nakryiko <[e-mail]>
Cc: Martin KaFai Lau <[e-mail]>
Cc: Eduard Zingerman <[e-mail]>
Cc: Song Liu <[e-mail]>
Cc: Yonghong Song <[e-mail]>
Cc: KP Singh <[e-mail]>
Cc: Stanislav Fomichev <[e-mail]>
Cc: Hao Luo <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Brendan Higgins <[e-mail]>
Cc: David Gow <[e-mail]>
Cc: Rae Moar <[e-mail]>
Cc: "David S. Miller" <[e-mail]>
Cc: Eric Dumazet <[e-mail]>
Cc: Jakub Kicinski <[e-mail]>
Cc: Paolo Abeni <[e-mail]>
Cc: Jiri Pirko <[e-mail]>
Cc: Petr Mladek <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Andy Shevchenko <[e-mail]>
Cc: Rasmus Villemoes <[e-mail]>
Cc: Sergey Senozhatsky <[e-mail]>
Cc: Stephen Hemminger <[e-mail]>
Cc: Jamal Hadi Salim <[e-mail]>
Cc: Cong Wang <[e-mail]>
Cc: Kent Overstreet <[e-mail]>
---
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: tags.
v3: - Update to linux 6.12rc1.
    - Add more Acked-by: tags.

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>
  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(-)

Comments

Jason A. Donenfeld Sept. 30, 2024, 1:25 p.m. UTC | #1

Hi Uros,

Per your plan, I took this into random.git, and we'll now see if being
in next unearths some problems over the next week or two.

Jason