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()

Author: torvalds

arch/riscv/include/asm/bitops.h

@@ -228,7 +228,7 @@ static __always_inline int variable_fls(unsigned int x)
  *
  * This operation may be reordered on other architectures than x86.
  */
-static inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(or, __NOP, nr, addr);
 }
@@ -240,7 +240,7 @@ static inline int arch_test_and_set_bit(int nr, volatile unsigned long *addr)
  *
  * This operation can be reordered on other architectures other than x86.
  */
-static inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(and, __NOT, nr, addr);
 }
@@ -253,7 +253,7 @@ static inline int arch_test_and_clear_bit(int nr, volatile unsigned long *addr)
  * This operation is atomic and cannot be reordered.
  * It also implies a memory barrier.
  */
-static inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
+static __always_inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit(xor, __NOP, nr, addr);
 }
@@ -270,7 +270,7 @@ static inline int arch_test_and_change_bit(int nr, volatile unsigned long *addr)
  * Note that @nr may be almost arbitrarily large; this function is not
  * restricted to acting on a single-word quantity.
  */
-static inline void arch_set_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_set_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(or, __NOP, nr, addr);
 }
@@ -284,7 +284,7 @@ static inline void arch_set_bit(int nr, volatile unsigned long *addr)
  * on non x86 architectures, so if you are writing portable code,
  * make sure not to rely on its reordering guarantees.
  */
-static inline void arch_clear_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_clear_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(and, __NOT, nr, addr);
 }
@@ -298,7 +298,7 @@ static inline void arch_clear_bit(int nr, volatile unsigned long *addr)
  * Note that @nr may be almost arbitrarily large; this function is not
  * restricted to acting on a single-word quantity.
  */
-static inline void arch_change_bit(int nr, volatile unsigned long *addr)
+static __always_inline void arch_change_bit(int nr, volatile unsigned long *addr)
 {
 	__op_bit(xor, __NOP, nr, addr);
 }
@@ -311,7 +311,7 @@ static inline void arch_change_bit(int nr, volatile unsigned long *addr)
  * This operation is atomic and provides acquire barrier semantics.
  * It can be used to implement bit locks.
  */
-static inline int arch_test_and_set_bit_lock(
+static __always_inline int arch_test_and_set_bit_lock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	return __test_and_op_bit_ord(or, __NOP, nr, addr, .aq);
@@ -324,7 +324,7 @@ static inline int arch_test_and_set_bit_lock(
  *
  * This operation is atomic and provides release barrier semantics.
  */
-static inline void arch_clear_bit_unlock(
+static __always_inline void arch_clear_bit_unlock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	__op_bit_ord(and, __NOT, nr, addr, .rl);
@@ -345,13 +345,13 @@ static inline void arch_clear_bit_unlock(
  * non-atomic property here: it's a lot more instructions and we still have to
  * provide release semantics anyway.
  */
-static inline void arch___clear_bit_unlock(
+static __always_inline void arch___clear_bit_unlock(
 	unsigned long nr, volatile unsigned long *addr)
 {
 	arch_clear_bit_unlock(nr, addr);
 }
 
-static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
+static __always_inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
 		volatile unsigned long *addr)
 {
 	unsigned long res;

include/linux/bits.h

@@ -20,9 +20,8 @@
  */
 #if !defined(__ASSEMBLY__)
 #include <linux/build_bug.h>
-#define GENMASK_INPUT_CHECK(h, l) \
-	(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
-		__is_constexpr((l) > (h)), (l) > (h), 0)))
+#include <linux/compiler.h>
+#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))
 #else
 /*
  * BUILD_BUG_ON_ZERO is not available in h files included from asm files,

include/linux/compiler.h

@@ -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.

include/linux/cpumask.h

@@ -391,7 +391,7 @@ unsigned int __pure cpumask_next_wrap(int n, const struct cpumask *mask, int sta
 	for_each_set_bit_from(cpu, cpumask_bits(mask), small_cpumask_bits)
 
 /**
- * cpumask_any_but - return a "random" in a cpumask, but not this one.
+ * cpumask_any_but - return an arbitrary cpu in a cpumask, but not this one.
  * @mask: the cpumask to search
  * @cpu: the cpu to ignore.
  *
@@ -411,7 +411,7 @@ unsigned int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
 }
 
 /**
- * cpumask_any_and_but - pick a "random" cpu from *mask1 & *mask2, but not this one.
+ * cpumask_any_and_but - pick an arbitrary cpu from *mask1 & *mask2, but not this one.
  * @mask1: the first input cpumask
  * @mask2: the second input cpumask
  * @cpu: the cpu to ignore
@@ -840,15 +840,15 @@ void cpumask_copy(struct cpumask *dstp, const struct cpumask *srcp)
 }
 
 /**
- * cpumask_any - pick a "random" cpu from *srcp
+ * cpumask_any - pick an arbitrary cpu from *srcp
  * @srcp: the input cpumask
  *
  * Return: >= nr_cpu_ids if no cpus set.
  */
 #define cpumask_any(srcp) cpumask_first(srcp)
 
 /**
- * cpumask_any_and - pick a "random" cpu from *mask1 & *mask2
+ * cpumask_any_and - pick an arbitrary cpu from *mask1 & *mask2
  * @mask1: the first input cpumask
  * @mask2: the second input cpumask
  *
@@ -1043,7 +1043,6 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS);
 /* Wrappers for arch boot code to manipulate normally-constant masks */
 void init_cpu_present(const struct cpumask *src);
 void init_cpu_possible(const struct cpumask *src);
-void init_cpu_online(const struct cpumask *src);
 
 #define assign_cpu(cpu, mask, val)	\
 	assign_bit(cpumask_check(cpu), cpumask_bits(mask), (val))

kernel/cpu.c

@@ -3128,11 +3128,6 @@ void init_cpu_possible(const struct cpumask *src)
 	cpumask_copy(&__cpu_possible_mask, src);
 }
 
-void init_cpu_online(const struct cpumask *src)
-{
-	cpumask_copy(&__cpu_online_mask, src);
-}
-
 void set_cpu_online(unsigned int cpu, bool online)
 {
 	/*