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Re: [libvirt] [PATCH 1/13] Adding recursive locks



On Thu, Mar 11, 2010 at 08:06:34AM -0500, Stefan Berger wrote:
> This patch adds recursive locks necessary due to the processing of
> network filter XML that can reference other network filters, including
> references that cause looks. Loops in the XML are prevented but their
> detection requires recursive locks.
> 

> ---
>  src/util/threads-pthread.c |   12 ++++++++++++
>  src/util/threads-pthread.h |    1 +
>  src/util/threads-win32.c   |    5 +++++
>  src/util/threads.h         |    1 +
>  4 files changed, 19 insertions(+)
> 
> Index: libvirt-acl/src/util/threads-pthread.c
> ===================================================================
> --- libvirt-acl.orig/src/util/threads-pthread.c
> +++ libvirt-acl/src/util/threads-pthread.c
> @@ -43,6 +43,18 @@ int virMutexInit(virMutexPtr m)
>      return 0;
>  }
>  
> +int virRecursiveMutexInit(virMutexPtr m)
> +{
> +    int ret;
> +    pthread_mutexattr_init(&m->attr);
> +    pthread_mutexattr_settype(&m->attr, PTHREAD_MUTEX_RECURSIVE);
> +    if ((ret = pthread_mutex_init(&m->lock, &m->attr)) != 0) {
> +        errno = ret;
> +        return -1;
> +    }
> +    return 0;
> +}
> +
>  void virMutexDestroy(virMutexPtr m)
>  {
>      pthread_mutex_destroy(&m->lock);

Minor point, I think it would be better to call it virMutexInitRecursive()
so we keep the standard virMutex prefix for naming convention


> Index: libvirt-acl/src/util/threads-pthread.h
> ===================================================================
> --- libvirt-acl.orig/src/util/threads-pthread.h
> +++ libvirt-acl/src/util/threads-pthread.h
> @@ -24,6 +24,7 @@
>  #include <pthread.h>
>  
>  struct virMutex {
> +    pthread_mutexattr_t attr;
>      pthread_mutex_t lock;
>  };

I don't think this is neccessary - the attributes are only used
at time of pthread_mutex_init() call, so don't need to be kept
around after that. Thus the 'pthread_mutexattr_t attr' could just
be a local variable in virRecursiveMutexInit().

>  
> Index: libvirt-acl/src/util/threads.h
> ===================================================================
> --- libvirt-acl.orig/src/util/threads.h
> +++ libvirt-acl/src/util/threads.h
> @@ -38,6 +38,7 @@ int virThreadInitialize(void) ATTRIBUTE_
>  void virThreadOnExit(void);
>  
>  int virMutexInit(virMutexPtr m) ATTRIBUTE_RETURN_CHECK;
> +int virRecursiveMutexInit(virMutexPtr m) ATTRIBUTE_RETURN_CHECK;
>  void virMutexDestroy(virMutexPtr m);
>  
>  void virMutexLock(virMutexPtr m);
> Index: libvirt-acl/src/util/threads-win32.c
> ===================================================================
> --- libvirt-acl.orig/src/util/threads-win32.c
> +++ libvirt-acl/src/util/threads-win32.c
> @@ -76,6 +76,11 @@ int virMutexInit(virMutexPtr m)
>      return 0;
>  }
>  
> +int virRecursiveMutexInit(virMutexPtr m)
> +{
> +    return virMutexInit(m);
> +}
> +
>  void virMutexDestroy(virMutexPtr m)
>  {
>      CloseHandle(m->lock);


Regards,
Daniel
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