[PATCH v0 1/4] bitops: add some atomic versions of bitmap operations

[Denis Plotnikov <dplotnikov@virtuozzo.com>]

1. test bit
2. test and set bit

Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 include/qemu/bitops.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h
index f55ce8b320..63218afa5a 100644
--- a/include/qemu/bitops.h
+++ b/include/qemu/bitops.h
@@ -95,6 +95,21 @@ static inline int test_and_set_bit(long nr, unsigned long *addr)
     return (old & mask) != 0;
 }
 
+/**
+ * test_and_set_bit_atomic - Set a bit atomically and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ */
+static inline int test_and_set_bit_atomic(long nr, unsigned long *addr)
+{
+    unsigned long mask = BIT_MASK(nr);
+    unsigned long *p = addr + BIT_WORD(nr);
+    unsigned long old;
+
+    old = atomic_fetch_or(p, mask);
+    return (old & mask) != 0;
+}
+
 /**
  * test_and_clear_bit - Clear a bit and return its old value
  * @nr: Bit to clear
@@ -135,6 +150,16 @@ static inline int test_bit(long nr, const unsigned long *addr)
     return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
 }
 
+/**
+ * test_bit_atomic - Determine whether a bit is set atomicallly
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */
+static inline int test_bit_atomic(long nr, const unsigned long *addr)
+{
+    long valid_nr = nr & (BITS_PER_LONG - 1);
+    return 1UL & (atomic_read(&addr[BIT_WORD(nr)]) >> valid_nr);
+}
 /**
  * find_last_bit - find the last set bit in a memory region
  * @addr: The address to start the search at
-- 
2.17.0