Debugging Tools for Windows

!deadlock

!deadlock扩展显示通过驱动程序验证器(Driver Verifier)的Deadlock Detection选项搜集的死锁(deadlock)信息。

语法

!deadlock
!deadlock 1

DLL

Windows 2000	不可用
Windows XP和之后	Kdexts.dll

注释

该扩展命令只有在驱动程序验证器的Deadlock Detection选项检测到加锁层次违例(lock hierarchy violation)并产生bug check 0xC4 (DRIVER_VERIFIER_DETECTED_VIOLATION)时，才能提供有用的信息。

不带任何参数时，!deadlock扩展显示基本的加锁的拓扑层次。如果问题不是一帮的循环死锁，该命令会描述遇到了什么情况。

!deadlock 1 扩展显示堆栈回溯。该堆栈是锁被请求时活动的调用堆栈。

下面是一个示例：

0:kd> !deadlock

Deadlock detected (2 resources in 2 threads):

Thread 0: A B
Thread 1: B A

Where:
Thread 0 = 8d3ba030
Thread 1 = 8d15c030
Lock A = bba2af30 Type 'Spinlock'
Lock B = dummy!GlobalLock Type 'Spinlock'

显示出了相关的锁和线程。但是，这只是一个摘要信息，可能还不足以调试遇到的问题。

使用!deadlock 1来打印出死锁相关的每个锁被请求时的堆栈回溯。由于这是运行时堆栈回溯，所以在使用调试版时会更加完整。在free版上，它们可能在一行之后就被截断了。

0:kd> !deadlock 1

Deadlock detected (2 resources in 2 threads):

Thread 0 (8D14F750) took locks in the following order:

    Lock A -- b7906f30 (Spinlock)
    Stack:   dummy!DummyActivateVcComplete+0x63
             dummy!dummyOpenVcChannels+0x2E1
             dummy!DummyAllocateRecvBufferComplete+0x436
             dummy!DummyAllocateComplete+0x55
             NDIS!ndisMQueuedAllocateSharedHandler+0xC9
             NDIS!ndisWorkerThread+0xEE

    Lock B -- dummy!GlobalLock (Spinlock)
    Stack:   dummy!dummyQueueRecvBuffers+0x2D
             dummy!DummyActivateVcComplete+0x90
             dummy!dummyOpenVcChannels+0x2E1
             dummy!DummyAllocateRecvBufferComplete+0x436
             dummy!DummyAllocateComplete+0x55

Thread 1 (8D903030) took locks in the following order:

    Lock B -- dummy!GlobalLock (Spinlock)
    Stack:   dummy!dummyRxInterruptOnCompletion+0x25D
             dummy!DummyHandleInterrupt+0x32F
             NDIS!ndisMDpcX+0x3C
             ntkrnlpa!KiRetireDpcList+0x5D

    Lock A -- b7906f30 (Spinlock)
    Stack:   << Current stack >>

除了当前堆栈之外，这些基本上就是所有需要的信息了。

0: kd> k
ChildEBP RetAddr
f78aae6c 80664c58 ntkrnlpa!DbgBreakPoint
f78aae74 8066523f ntkrnlpa!ViDeadlockReportIssue+0x2f
f78aae9c 806665df ntkrnlpa!ViDeadlockAnalyze+0x253
f78aaee8 8065d944 ntkrnlpa!VfDeadlockAcquireResource+0x20b
f78aaf08 bfd6df46 ntkrnlpa!VerifierKeAcquireSpinLockAtDpcLevel+0x44
f78aafa4 b1bf2d2d dummy!dummyRxInterruptOnCompletion+0x2b5
f78aafc4 bfde9d8c dummy!DummyHandleInterrupt+0x32f
f78aafd8 804b393b NDIS!ndisMDpcX+0x3c
f78aaff4 804b922b ntkrnlpa!KiRetireDpcList+0x5d

从上面这些可以知道有哪些相关的锁，以及它们在什么地方被请求的。这对于调试死锁来说已经包含了足够信息。如果可以使用源码，则还可以使用调试器来查看问题具体出现在什么地方：

0: kd> .lines
Line number information will be loaded

0: kd> u dummy!DummyActivateVcComplete+0x63 l1
dummy!DummyActivateVcComplete+63 [d:\nt\drivers\dummy\vc.c @ 2711]:
b1bfe6c9 837d0c00         cmp     dword ptr [ebp+0xc],0x0

0: kd> u dummy!dummyQueueRecvBuffers+0x2D l1
dummy!dummyQueueRecvBuffers+2d [d:\nt\drivers\dummy\receive.c @ 2894]:
b1bf4e39 807d0c01         cmp     byte ptr [ebp+0xc],0x1

0: kd> u dummy!dummyRxInterruptOnCompletion+0x25D l1
dummy!dummyRxInterruptOnCompletion+25d [d:\nt\drivers\dummy\receive.c @ 1424]:
b1bf5d05 85f6             test    esi,esi

0: kd> u dummy!dummyRxInterruptOnCompletion+0x2b5 l1
dummy!dummyRxInterruptOnCompletion+2b5 [d:\nt\drivers\dummy\receive.c @ 1441]:
b1bf5d5d 8b4648           mov     eax,[esi+0x48]

现在就知道了源文件的名字，以及请求锁的位置的行号。这种情况下，源文件表明了这些线程的行为如下：

线程1: DummyActivateVcComplete获得了dummy小端口锁(miniport lock)。然后调用dummyQueueRecvBuffers，它会请求dummy global lock。
线程2: dummyRxInterruptOnCompletion获得了global lock。然后，几行之后又请求小端口锁。

通过这点，死锁原因就清楚了。

附加信息

关于驱动程序验证器的信息，查看Windows Driver Kit (WDK) 文档。

Build machine: CAPEBUILD