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Re: [libvirt] Potential race condition problem



On 09/29/2012 03:07 PM, Benjamin Wang (gendwang) wrote:

Hi,

   Currently virInitialize() method defined in libvirt.c has the following code:

int

virInitialize(void)

{

    if (initialized)

        return 0;

 

    initialized = 1;

 

    if (virThreadInitialize() < 0 ||

        virErrorInitialize() < 0 ||

        virRandomInitialize(time(NULL) ^ getpid()) ||

        virNodeSuspendInit() < 0)

        return -1;

 

……

}

 

When two threads access virInitialize method, there is no lock for the “initialized” parameter. If the first thread enters this method and set “initialized” to 1,

the second thread could see that “initialized” is 1(Because initialized is not volatiled, I say could). In some situation, before the first thread finishes all the initialization,

the second thread could use some resources which should be initialized in Initialize method.

If you have any comments, please let me know. Thanks!

 

B.R.

Benjamin Wang



      As the comments above the function said,
      "It's better to call this routine at startup in multithreaded applications to avoid potential race when initializing the library."
     

      Guannan



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