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ntdll: Add a futex-based implementation of WaitOnAddress(). 

Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Zebediah Figura 2019-02-05 20:21:07 -06:00 committed by Alexandre Julliard
parent 749fe42d1f
commit cc8f9b6419
1 changed files with 139 additions and 0 deletions
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139
dlls/ntdll/sync.c
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@ -26,7 +26,11 @@
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <signal.h>
#ifdef HAVE_SYS_SYSCALL_H
#include <sys/syscall.h>
#endif
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
@ -63,6 +67,8 @@ HANDLE keyed_event = NULL;
static const LARGE_INTEGER zero_timeout;
#define TICKSPERSEC 10000000
static inline int interlocked_dec_if_nonzero( int *dest )
{
int val, tmp;
@ -74,6 +80,41 @@ static inline int interlocked_dec_if_nonzero( int *dest )
return val;
}
#ifdef __linux__
static int wait_op = 128; /*FUTEX_WAIT|FUTEX_PRIVATE_FLAG*/
static int wake_op = 129; /*FUTEX_WAKE|FUTEX_PRIVATE_FLAG*/
static inline int futex_wait( const int *addr, int val, struct timespec *timeout )
{
return syscall( __NR_futex, addr, wait_op, val, timeout, 0, 0 );
}
static inline int futex_wake( const int *addr, int val )
{
return syscall( __NR_futex, addr, wake_op, val, NULL, 0, 0 );
}
static inline int use_futexes(void)
{
static int supported = -1;
if (supported == -1)
{
futex_wait( &supported, 10, NULL );
if (errno == ENOSYS)
{
wait_op = 0; /*FUTEX_WAIT*/
wake_op = 1; /*FUTEX_WAKE*/
futex_wait( &supported, 10, NULL );
}
supported = (errno != ENOSYS);
}
return supported;
}
#endif
/* creates a struct security_descriptor and contained information in one contiguous piece of memory */
NTSTATUS alloc_object_attributes( const OBJECT_ATTRIBUTES *attr, struct object_attributes **ret,
data_size_t *ret_len )
@ -1987,6 +2028,95 @@ static BOOL compare_addr( const void *addr, const void *cmp, SIZE_T size )
return FALSE;
}
#ifdef __linux__
/* We can't map addresses to futex directly, because an application can wait on
* 8 bytes, and we can't pass all 8 as the compare value to futex(). Instead we
* map all addresses to a small fixed table of futexes. This may result in
* spurious wakes, but the application is already expected to handle those. */
static int addr_futex_table[256];
static inline int *hash_addr( const void *addr )
{
ULONG_PTR val = (ULONG_PTR)addr;
return &addr_futex_table[(val >> 2) & 255];
}
static inline NTSTATUS fast_wait_addr( const void *addr, const void *cmp, SIZE_T size,
const LARGE_INTEGER *timeout )
{
int *futex;
int val;
LARGE_INTEGER now;
timeout_t diff;
struct timespec timespec;
int ret;
if (!use_futexes())
return STATUS_NOT_IMPLEMENTED;
futex = hash_addr( addr );
/* We must read the previous value of the futex before checking the value
* of the address being waited on. That way, if we receive a wake between
* now and waiting on the futex, we know that val will have changed.
* Use an atomic load so that memory accesses are ordered between this read
* and the increment below. */
val = interlocked_cmpxchg( futex, 0, 0 );
if (!compare_addr( addr, cmp, size ))
return STATUS_SUCCESS;
if (timeout)
{
if (timeout->QuadPart > 0)
{
NtQuerySystemTime( &now );
diff = timeout->QuadPart - now.QuadPart;
}
else
diff = -timeout->QuadPart;
timespec.tv_sec = diff / TICKSPERSEC;
timespec.tv_nsec = (diff % TICKSPERSEC) * 100;
ret = futex_wait( futex, val, &timespec );
}
else
ret = futex_wait( futex, val, NULL );
if (ret == -1 && errno == ETIMEDOUT)
return STATUS_TIMEOUT;
return STATUS_SUCCESS;
}
static inline NTSTATUS fast_wake_addr( const void *addr )
{
int *futex;
if (!use_futexes())
return STATUS_NOT_IMPLEMENTED;
futex = hash_addr( addr );
interlocked_xchg_add( futex, 1 );
futex_wake( futex, INT_MAX );
return STATUS_SUCCESS;
}
#else
static inline NTSTATUS fast_wait_addr( const void *addr, const void *cmp, SIZE_T size,
const LARGE_INTEGER *timeout )
{
return STATUS_NOT_IMPLEMENTED;
}
static inline NTSTATUS fast_wake_addr( const void *addr )
{
return STATUS_NOT_IMPLEMENTED;
}
#endif
/***********************************************************************
* RtlWaitOnAddress (NTDLL.@)
*/
@ -2005,6 +2135,9 @@ NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size
if (size != 1 && size != 2 && size != 4 && size != 8)
return STATUS_INVALID_PARAMETER;
if ((ret = fast_wait_addr( addr, cmp, size, timeout )) != STATUS_NOT_IMPLEMENTED)
return ret;
select_op.keyed_event.op = SELECT_KEYED_EVENT_WAIT;
select_op.keyed_event.handle = wine_server_obj_handle( keyed_event );
select_op.keyed_event.key = wine_server_client_ptr( addr );
@ -2059,6 +2192,9 @@ NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size
*/
void WINAPI RtlWakeAddressAll( const void *addr )
{
if (fast_wake_addr( addr ) != STATUS_NOT_IMPLEMENTED)
return;
RtlEnterCriticalSection( &addr_section );
while (NtReleaseKeyedEvent( 0, addr, 0, &zero_timeout ) == STATUS_SUCCESS) {}
RtlLeaveCriticalSection( &addr_section );
@ -2069,6 +2205,9 @@ void WINAPI RtlWakeAddressAll( const void *addr )
*/
void WINAPI RtlWakeAddressSingle( const void *addr )
{
if (fast_wake_addr( addr ) != STATUS_NOT_IMPLEMENTED)
return;
RtlEnterCriticalSection( &addr_section );
NtReleaseKeyedEvent( 0, addr, 0, &zero_timeout );
RtlLeaveCriticalSection( &addr_section );