Merge tag 'bitmap-for-6.14' of https://github.com:/norov/linux

Pull bitmap updates from Yury Norov:
 "This includes const_true() series from Vincent Mailhol, another
  __always_inline rework from Nathan Chancellor for RISCV, and a couple
  of random fixes from Dr. David Alan Gilbert and I Hsin Cheng"

* tag 'bitmap-for-6.14' of https://github.com:/norov/linux:
  cpumask: Rephrase comments for cpumask_any*() APIs
  cpu: Remove unused init_cpu_online
  riscv: Always inline bitops
  linux/bits.h: simplify GENMASK_INPUT_CHECK()
  compiler.h: add const_true()
This commit is contained in:
Linus Torvalds
2025-01-26 14:03:44 -08:00
5 changed files with 38 additions and 23 deletions

View File

@@ -307,6 +307,28 @@ static inline void *offset_to_ptr(const int *off)
*/
#define statically_true(x) (__builtin_constant_p(x) && (x))
/*
* Similar to statically_true() but produces a constant expression
*
* To be used in conjunction with macros, such as BUILD_BUG_ON_ZERO(),
* which require their input to be a constant expression and for which
* statically_true() would otherwise fail.
*
* This is a trade-off: const_true() requires all its operands to be
* compile time constants. Else, it would always returns false even on
* the most trivial cases like:
*
* true || non_const_var
*
* On the opposite, statically_true() is able to fold more complex
* tautologies and will return true on expressions such as:
*
* !(non_const_var * 8 % 4)
*
* For the general case, statically_true() is better.
*/
#define const_true(x) __builtin_choose_expr(__is_constexpr(x), x, false)
/*
* This is needed in functions which generate the stack canary, see
* arch/x86/kernel/smpboot.c::start_secondary() for an example.