Merge tag 'bitmap-6.0-rc1' of https://github.com/norov/linux

[linux-2.6-microblaze.git] / include / asm-generic / bitops / generic-non-atomic.h

diff --git a/include/asm-generic/bitops/generic-non-atomic.h b/include/asm-generic/bitops/generic-non-atomic.h
new file mode 100644 (file)
index 0000000..3d5ebd2
--- /dev/null
+++ b/include/asm-generic/bitops/generic-non-atomic.h
@@ -0,0 +1,161 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H
+#define __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H
+
+#include <linux/bits.h>
+
+#ifndef _LINUX_BITOPS_H
+#error only <linux/bitops.h> can be included directly
+#endif
+
+/*
+ * Generic definitions for bit operations, should not be used in regular code
+ * directly.
+ */
+
+/**
+ * generic___set_bit - Set a bit in memory
+ * @nr: the bit to set
+ * @addr: the address to start counting from
+ *
+ * Unlike set_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static __always_inline void
+generic___set_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+       *p  |= mask;
+}
+
+static __always_inline void
+generic___clear_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+       *p &= ~mask;
+}
+
+/**
+ * generic___change_bit - Toggle a bit in memory
+ * @nr: the bit to change
+ * @addr: the address to start counting from
+ *
+ * Unlike change_bit(), this function is non-atomic and may be reordered.
+ * If it's called on the same region of memory simultaneously, the effect
+ * may be that only one operation succeeds.
+ */
+static __always_inline void
+generic___change_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+
+       *p ^= mask;
+}
+
+/**
+ * generic___test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static __always_inline bool
+generic___test_and_set_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+       unsigned long old = *p;
+
+       *p = old | mask;
+       return (old & mask) != 0;
+}
+
+/**
+ * generic___test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail.  You must protect multiple accesses with a lock.
+ */
+static __always_inline bool
+generic___test_and_clear_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+       unsigned long old = *p;
+
+       *p = old & ~mask;
+       return (old & mask) != 0;
+}
+
+/* WARNING: non atomic and it can be reordered! */
+static __always_inline bool
+generic___test_and_change_bit(unsigned long nr, volatile unsigned long *addr)
+{
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+       unsigned long old = *p;
+
+       *p = old ^ mask;
+       return (old & mask) != 0;
+}
+
+/**
+ * generic_test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */
+static __always_inline bool
+generic_test_bit(unsigned long nr, const volatile unsigned long *addr)
+{
+       /*
+        * Unlike the bitops with the '__' prefix above, this one *is* atomic,
+        * so `volatile` must always stay here with no cast-aways. See
+        * `Documentation/atomic_bitops.txt` for the details.
+        */
+       return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
+}
+
+/*
+ * const_*() definitions provide good compile-time optimizations when
+ * the passed arguments can be resolved at compile time.
+ */
+#define const___set_bit                        generic___set_bit
+#define const___clear_bit              generic___clear_bit
+#define const___change_bit             generic___change_bit
+#define const___test_and_set_bit       generic___test_and_set_bit
+#define const___test_and_clear_bit     generic___test_and_clear_bit
+#define const___test_and_change_bit    generic___test_and_change_bit
+
+/**
+ * const_test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ *
+ * A version of generic_test_bit() which discards the `volatile` qualifier to
+ * allow a compiler to optimize code harder. Non-atomic and to be called only
+ * for testing compile-time constants, e.g. by the corresponding macros, not
+ * directly from "regular" code.
+ */
+static __always_inline bool
+const_test_bit(unsigned long nr, const volatile unsigned long *addr)
+{
+       const unsigned long *p = (const unsigned long *)addr + BIT_WORD(nr);
+       unsigned long mask = BIT_MASK(nr);
+       unsigned long val = *p;
+
+       return !!(val & mask);
+}
+
+#endif /* __ASM_GENERIC_BITOPS_GENERIC_NON_ATOMIC_H */