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ntdll-NtAlertThreadByThreadId: Avoid spurious wakeups by performing the comparison inside of the futex queue spinlock.

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Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=50680
This commit is contained in:
Zebediah Figura 2021-11-12 00:25:51 -06:00
parent b090c12d6d
commit 45230b51db
1 changed files with 25 additions and 66 deletions
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91
patches/ntdll-NtAlertThreadByThreadId/0007-ntdll-Reimplement-Win32-futexes-on-top-of-thread-ID-.patch
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@ -1,4 +1,4 @@
From 08cec34b6dccea0cf7e8f880911786fd385ed78a Mon Sep 17 00:00:00 2001
From 4b2ad3bf49e77c6cb0e541329ac851d054e6f649 Mon Sep 17 00:00:00 2001
From: Zebediah Figura <z.figura12@gmail.com>
Date: Mon, 7 Jun 2021 16:26:18 -0500
Subject: [PATCH] ntdll: Reimplement Win32 futexes on top of thread-ID alerts.
@ -6,14 +6,14 @@ Subject: [PATCH] ntdll: Reimplement Win32 futexes on top of thread-ID alerts.
Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Zebediah Figura <zfigura@codeweavers.com>
---
dlls/ntdll/sync.c | 214 ++++++++++++++++++++++++++++++++++++++-
dlls/ntdll/sync.c | 173 ++++++++++++++++++++++++++++++++++++++-
dlls/ntdll/unix/loader.c | 3 -
dlls/ntdll/unix/sync.c | 162 -----------------------------
dlls/ntdll/unix/sync.c | 162 ------------------------------------
dlls/ntdll/unixlib.h | 6 +-
4 files changed, 212 insertions(+), 173 deletions(-)
4 files changed, 171 insertions(+), 173 deletions(-)
diff --git a/dlls/ntdll/sync.c b/dlls/ntdll/sync.c
index bfb30661864..db68a466d8a 100644
index bfb30661864..adc03c9ff7a 100644
--- a/dlls/ntdll/sync.c
+++ b/dlls/ntdll/sync.c
@@ -34,11 +34,18 @@
@ -35,7 +35,7 @@ index bfb30661864..db68a466d8a 100644
/******************************************************************
* RtlRunOnceInitialize (NTDLL.@)
*/
@@ -863,13 +870,142 @@ NTSTATUS WINAPI RtlSleepConditionVariableSRW( RTL_CONDITION_VARIABLE *variable,
@@ -863,13 +870,111 @@ NTSTATUS WINAPI RtlSleepConditionVariableSRW( RTL_CONDITION_VARIABLE *variable,
return status;
}
@ -72,22 +72,6 @@ index bfb30661864..db68a466d8a 100644
+ return &futex_queues[(val >> 4) % ARRAY_SIZE(futex_queues)];
+}
+
+static void spin_rdlock( LONG *lock )
+{
+ for (;;)
+ {
+ LONG old = *lock;
+ if (old != -1 && InterlockedCompareExchange( lock, old + 1, old ) == old)
+ return;
+ YieldProcessor();
+ }
+}
+
+static void spin_rdunlock( LONG *lock )
+{
+ InterlockedDecrement( lock );
+}
+
+static void spin_wrlock( LONG *lock )
+{
+ while (InterlockedCompareExchange( lock, -1, 0 ))
@ -136,35 +120,20 @@ index bfb30661864..db68a466d8a 100644
+ entry.tid = GetCurrentThreadId();
+
+ spin_wrlock( &queue->lock );
+
+ if (!compare_addr( addr, cmp, size ))
+ {
+ spin_wrunlock( &queue->lock );
+ return STATUS_SUCCESS;
+ }
+
+ if (!queue->queue.next)
+ list_init(&queue->queue);
+ list_init( &queue->queue );
+ list_add_tail( &queue->queue, &entry.entry );
+
+ spin_wrunlock( &queue->lock );
+
+ /* Ensure that the store above is ordered before the comparison below.
+ * This barrier is paired with another in RtlWakeByAddress*().
+ *
+ * In more detail, given the following sequence:
+ *
+ * Thread A Thread B
+ * -----------------------------------------------------------------
+ * RtlWaitOnAddress( &val ); val = 1;
+ * queue thread RtlWakeByAddress( &val );
+ * MemoryBarrier(); <---- paired with ----> MemoryBarrier();
+ * compare_addr( &val ); if (thread is queued)
+ *
+ * We must ensure that the thread is queued [through the above
+ * InterlockedExchangePointer()] before reading "val", and that writes to
+ * "val" by the application happen before we check for queued threads.
+ * Otherwise, thread A can deadlock: "val" may appear unchanged, while
+ * thread B observed that thread A was not queued.
+ */
+ MemoryBarrier();
+
+ if (compare_addr( addr, cmp, size ))
+ ret = NtWaitForAlertByThreadId( NULL, timeout );
+ else
+ ret = STATUS_SUCCESS;
+ ret = NtWaitForAlertByThreadId( NULL, timeout );
+
+ spin_wrlock( &queue->lock );
+ /* We may have already been removed by a call to RtlWakeAddressSingle(). */
@ -179,7 +148,7 @@ index bfb30661864..db68a466d8a 100644
}
/***********************************************************************
@@ -877,7 +1013,42 @@ NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size
@@ -877,7 +982,37 @@ NTSTATUS WINAPI RtlWaitOnAddress( const void *addr, const void *cmp, SIZE_T size
*/
void WINAPI RtlWakeAddressAll( const void *addr )
{
@ -193,11 +162,6 @@ index bfb30661864..db68a466d8a 100644
+
+ if (!addr) return;
+
+ /* Ensure that memory stores to "addr" are ordered before reading the
+ * array below. Paired with another barrier in RtlWaitOnAddress() [q.v.].
+ */
+ MemoryBarrier();
+
+ spin_wrlock( &queue->lock );
+
+ if (!queue->queue.next)
@ -223,7 +187,7 @@ index bfb30661864..db68a466d8a 100644
}
/***********************************************************************
@@ -885,5 +1056,42 @@ void WINAPI RtlWakeAddressAll( const void *addr )
@@ -885,5 +1020,37 @@ void WINAPI RtlWakeAddressAll( const void *addr )
*/
void WINAPI RtlWakeAddressSingle( const void *addr )
{
@ -236,11 +200,6 @@ index bfb30661864..db68a466d8a 100644
+
+ if (!addr) return;
+
+ /* Ensure that memory stores to "addr" are ordered before reading the
+ * array below. Paired with another barrier in RtlWaitOnAddress() [q.v.].
+ */
+ MemoryBarrier();
+
+ spin_wrlock( &queue->lock );
+
+ if (!queue->queue.next)
@ -268,10 +227,10 @@ index bfb30661864..db68a466d8a 100644
+ if (tid) NtAlertThreadByThreadId( (HANDLE)(DWORD_PTR)tid );
}
diff --git a/dlls/ntdll/unix/loader.c b/dlls/ntdll/unix/loader.c
index 7f36dc42579..05ae264297a 100644
index a411b01a389..59bc978022c 100644
--- a/dlls/ntdll/unix/loader.c
+++ b/dlls/ntdll/unix/loader.c
@@ -2145,9 +2145,6 @@ static struct unix_funcs unix_funcs =
@@ -2146,9 +2146,6 @@ static struct unix_funcs unix_funcs =
NtCurrentTeb,
#endif
RtlGetSystemTimePrecise,
@ -282,10 +241,10 @@ index 7f36dc42579..05ae264297a 100644
fast_RtlpUnWaitCriticalSection,
fast_RtlDeleteCriticalSection,
diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index cdc63c8a6ef..47a0a03b45f 100644
index ce78c11fd4b..c37dbc5e96e 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -73,10 +73,6 @@ WINE_DEFAULT_DEBUG_CHANNEL(sync);
@@ -74,10 +74,6 @@ WINE_DEFAULT_DEBUG_CHANNEL(sync);
HANDLE keyed_event = 0;
@ -296,7 +255,7 @@ index cdc63c8a6ef..47a0a03b45f 100644
static const char *debugstr_timeout( const LARGE_INTEGER *timeout )
{
if (!timeout) return "(infinite)";
@@ -186,24 +182,6 @@ static void timespec_from_timeout( struct timespec *timespec, const LARGE_INTEGE
@@ -187,24 +183,6 @@ static void timespec_from_timeout( struct timespec *timespec, const LARGE_INTEGE
#endif
@ -321,7 +280,7 @@ index cdc63c8a6ef..47a0a03b45f 100644
/* create 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 )
@@ -2977,71 +2955,6 @@ NTSTATUS CDECL fast_RtlWakeConditionVariable( RTL_CONDITION_VARIABLE *variable,
@@ -3035,71 +3013,6 @@ NTSTATUS CDECL fast_RtlWakeConditionVariable( RTL_CONDITION_VARIABLE *variable,
return STATUS_SUCCESS;
}
@ -393,7 +352,7 @@ index cdc63c8a6ef..47a0a03b45f 100644
#else
NTSTATUS CDECL fast_RtlTryAcquireSRWLockExclusive( RTL_SRWLOCK *lock )
@@ -3084,79 +2997,4 @@ NTSTATUS CDECL fast_wait_cv( RTL_CONDITION_VARIABLE *variable, const void *value
@@ -3142,79 +3055,4 @@ NTSTATUS CDECL fast_wait_cv( RTL_CONDITION_VARIABLE *variable, const void *value
return STATUS_NOT_IMPLEMENTED;
}