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Revision tags: v6.15, v6.15-rc7, v6.15-rc6, v6.15-rc5, v6.15-rc4, v6.15-rc3, v6.15-rc2, v6.15-rc1, v6.14, v6.14-rc7, v6.14-rc6, v6.14-rc5, v6.14-rc4, v6.14-rc3, v6.14-rc2, v6.14-rc1, v6.13, v6.13-rc7, v6.13-rc6, v6.13-rc5, v6.13-rc4, v6.13-rc3, v6.13-rc2, v6.13-rc1, v6.12, v6.12-rc7, v6.12-rc6, v6.12-rc5, v6.12-rc4, v6.12-rc3, v6.12-rc2, v6.12-rc1, v6.11, v6.11-rc7, v6.11-rc6, v6.11-rc5, v6.11-rc4, v6.11-rc3, v6.11-rc2, v6.11-rc1, v6.10, v6.10-rc7, v6.10-rc6, v6.10-rc5, v6.10-rc4, v6.10-rc3, v6.10-rc2, v6.10-rc1, v6.9, v6.9-rc7, v6.9-rc6, v6.9-rc5, v6.9-rc4, v6.9-rc3, v6.9-rc2, v6.9-rc1 |
| #
a88d970c |
| 17-Mar-2024 |
Paul E. McKenney <[email protected]> |
lib: Add one-byte emulation function
Architectures are required to provide four-byte cmpxchg() and 64-bit
architectures are additionally required to provide eight-byte cmpxchg().
However, there are
lib: Add one-byte emulation function
Architectures are required to provide four-byte cmpxchg() and 64-bit
architectures are additionally required to provide eight-byte cmpxchg().
However, there are cases where one-byte cmpxchg() would be extremely
useful. Therefore, provide cmpxchg_emu_u8() that emulates one-byte
cmpxchg() in terms of four-byte cmpxchg().
Note that this emulations is fully ordered, and can (for example) cause
one-byte cmpxchg_relaxed() to incur the overhead of full ordering.
If this causes problems for a given architecture, that architecture is
free to provide its own lighter-weight primitives.
[ paulmck: Apply Marco Elver feedback. ]
[ paulmck: Apply kernel test robot feedback. ]
[ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
Link: https://lore.kernel.org/all/0733eb10-5e7a-4450-9b8a-527b97c842ff@paulmck-laptop/
Signed-off-by: Paul E. McKenney <[email protected]>
Acked-by: Marco Elver <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "Peter Zijlstra (Intel)" <[email protected]>
Cc: Douglas Anderson <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: <[email protected]>
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