queue-5.10/u64_stats-fix-u64_stats_init-for-lockdep-when-used-r.patch

   1 From d126067245d71c1d4a831a86eedbc702a5c6480a Mon Sep 17 00:00:00 2001
   2 From: Sasha Levin <sashal@kernel.org>
   3 Date: Thu, 4 Apr 2024 09:57:40 +0200
   4 Subject: u64_stats: fix u64_stats_init() for lockdep when used repeatedly in
   5  one file
   6
   7 From: Petr Tesarik <petr@tesarici.cz>
   8
   9 [ Upstream commit 38a15d0a50e0a43778561a5861403851f0b0194c ]
  10
  11 Fix bogus lockdep warnings if multiple u64_stats_sync variables are
  12 initialized in the same file.
  13
  14 With CONFIG_LOCKDEP, seqcount_init() is a macro which declares:
  15
  16         static struct lock_class_key __key;
  17
  18 Since u64_stats_init() is a function (albeit an inline one), all calls
  19 within the same file end up using the same instance, effectively treating
  20 them all as a single lock-class.
  21
  22 Fixes: 9464ca650008 ("net: make u64_stats_init() a function")
  23 Closes: https://lore.kernel.org/netdev/ea1567d9-ce66-45e6-8168-ac40a47d1821@roeck-us.net/
  24 Signed-off-by: Petr Tesarik <petr@tesarici.cz>
  25 Reviewed-by: Simon Horman <horms@kernel.org>
  26 Reviewed-by: Eric Dumazet <edumazet@google.com>
  27 Link: https://lore.kernel.org/r/20240404075740.30682-1-petr@tesarici.cz
  28 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
  29 Signed-off-by: Sasha Levin <sashal@kernel.org>
  30 ---
  31  include/linux/u64_stats_sync.h | 9 +++++----
  32  1 file changed, 5 insertions(+), 4 deletions(-)
  33
  34 diff --git a/include/linux/u64_stats_sync.h b/include/linux/u64_stats_sync.h
  35 index 51f2e16b9540b..11c3162dade3b 100644
  36 --- a/include/linux/u64_stats_sync.h
  37 +++ b/include/linux/u64_stats_sync.h
  38 @@ -125,10 +125,11 @@ static inline void u64_stats_inc(u64_stats_t *p)
  39         p->v++;
  40  }
  41
  42 -static inline void u64_stats_init(struct u64_stats_sync *syncp)
  43 -{
  44 -       seqcount_init(&syncp->seq);
  45 -}
  46 +#define u64_stats_init(syncp)                          \
  47 +       do {                                            \
  48 +               struct u64_stats_sync *__s = (syncp);   \
  49 +               seqcount_init(&__s->seq);               \
  50 +       } while (0)
  51
  52  static inline void __u64_stats_update_begin(struct u64_stats_sync *syncp)
  53  {
  54 --
  55 2.43.0
  56