Zebediah Figura : ntdll: Add a futex-based implementation of WaitOnAddress ().
Module: wine Branch: master Commit: cc8f9b64194f115de1161526e2f0ebbcb0bdcc4b URL: https://source.winehq.org/git/wine.git/?a=commit;h=cc8f9b64194f115de1161526e... Author: Zebediah Figura <z.figura12(a)gmail.com> Date: Tue Feb 5 20:21:07 2019 -0600 ntdll: Add a futex-based implementation of WaitOnAddress(). Signed-off-by: Zebediah Figura <z.figura12(a)gmail.com> Signed-off-by: Alexandre Julliard <julliard(a)winehq.org> --- dlls/ntdll/sync.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 139 insertions(+) diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c index 62cb3cd..8513561 100644 --- a/dlls/ntdll/sync.c +++ b/dlls/ntdll/sync.c @@ -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, ×pec ); + } + 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 );
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Alexandre Julliard