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property: fix getting dirty serial value

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__system_property_serial just returned serial value without
checking if it is dirty, so check and wait until serial
value is not dirty before return

Change-Id: If485b6251b5555b004912c66c7c2cb455a7fdbdc
Signed-off-by: jiaguo <jiaguo@marvell.com>
This commit is contained in:
jiaguo
2014-03-13 17:39:58 +08:00
committed by Elliott Hughes
parent 01cd78854a
commit 879d330499
1 changed files with 14 additions and 14 deletions
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20
libc/bionic/system_properties.cpp
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@@ -609,19 +609,13 @@ const prop_info *__system_property_find(const char *name)
int __system_property_read(const prop_info *pi, char *name, char *value) int __system_property_read(const prop_info *pi, char *name, char *value)
{ {
unsigned serial, len;
if (__predict_false(compat_mode)) { if (__predict_false(compat_mode)) {
return __system_property_read_compat(pi, name, value); return __system_property_read_compat(pi, name, value);
} }
for(;;) { while (true) {
serial = pi->serial; uint32_t serial = __system_property_serial(pi);
while(SERIAL_DIRTY(serial)) { size_t len = SERIAL_VALUE_LEN(serial);
__futex_wait((volatile void *)&pi->serial, serial, NULL);
serial = pi->serial;
}
len = SERIAL_VALUE_LEN(serial);
memcpy(value, pi->value, len + 1); memcpy(value, pi->value, len + 1);
ANDROID_MEMBAR_FULL(); ANDROID_MEMBAR_FULL();
if (serial == pi->serial) { if (serial == pi->serial) {
@@ -702,6 +696,7 @@ int __system_property_update(prop_info *pi, const char *value, unsigned int len)
return 0; return 0;
} }
int __system_property_add(const char *name, unsigned int namelen, int __system_property_add(const char *name, unsigned int namelen,
const char *value, unsigned int valuelen) const char *value, unsigned int valuelen)
{ {
@@ -726,7 +721,12 @@ int __system_property_add(const char *name, unsigned int namelen,
unsigned int __system_property_serial(const prop_info *pi) unsigned int __system_property_serial(const prop_info *pi)
{ {
return pi->serial; uint32_t serial = pi->serial;
while (SERIAL_DIRTY(serial)) {
__futex_wait(const_cast<volatile uint32_t*>(&pi->serial), serial, NULL);
serial = pi->serial;
}
return serial;
} }
unsigned int __system_property_wait_any(unsigned int serial) unsigned int __system_property_wait_any(unsigned int serial)