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Merge "Work around atomic_load(const T*) issues."

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Hans Boehm 2014-08-19 22:34:00 +00:00 committed by Gerrit Code Review
commit b61c50647b
1 changed files with 11 additions and 3 deletions
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14
libc/bionic/system_properties.cpp
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@ -611,6 +611,14 @@ const prop_info *__system_property_find(const char *name)
return find_property(root_node(), name, strlen(name), NULL, 0, false);
}
// The C11 standard doesn't allow atomic loads from const fields,
// though C++11 does. Fudge it until standards get straightened out.
static inline uint_least32_t load_const_atomic(const atomic_uint_least32_t* s,
memory_order mo) {
atomic_uint_least32_t* non_const_s = const_cast<atomic_uint_least32_t*>(s);
return atomic_load_explicit(non_const_s, mo);
}
int __system_property_read(const prop_info *pi, char *name, char *value)
{
if (__predict_false(compat_mode)) {
@ -631,7 +639,7 @@ int __system_property_read(const prop_info *pi, char *name, char *value)
// would be any different, so this should be OK.
atomic_thread_fence(memory_order_acquire);
if (serial ==
atomic_load_explicit(&(pi->serial), memory_order_relaxed)) {
load_const_atomic(&(pi->serial), memory_order_relaxed)) {
if (name != 0) {
strcpy(name, pi->name);
}
@ -733,12 +741,12 @@ int __system_property_add(const char *name, unsigned int namelen,
// Wait for non-locked serial, and retrieve it with acquire semantics.
unsigned int __system_property_serial(const prop_info *pi)
{
uint32_t serial = atomic_load_explicit(&pi->serial, memory_order_acquire);
uint32_t serial = load_const_atomic(&pi->serial, memory_order_acquire);
while (SERIAL_DIRTY(serial)) {
__futex_wait(const_cast<volatile void *>(
reinterpret_cast<const void *>(&pi->serial)),
serial, NULL);
serial = atomic_load_explicit(&pi->serial, memory_order_acquire);
serial = load_const_atomic(&pi->serial, memory_order_acquire);
}
return serial;
}