[libcxx-commits] [PATCH] D64299: Make ~mutex and ~condition_variable trivial with Bionic pthreads

[Dmitry Vyukov via Phabricator via libcxx-commits]

dvyukov added a comment.

In D64299#1590038 <https://reviews.llvm.org/D64299#1590038>, @eugenis wrote:

> In D64299#1588931 <https://reviews.llvm.org/D64299#1588931>, @dvyukov wrote:
>
> > In D64299#1588251 <https://reviews.llvm.org/D64299#1588251>, @eugenis wrote:
> >
> > > This feels like the right trade-off.
> > >
> > > TSan should be fine with a mutex that is never destroyed, but it will not be able to catch lock-after-destroy bugs on such mutex obviously.
> > >  @dvyukov
> >
> >
> > Effectively pthread_mutex_destroy is not trivial under tsan so, yes, there will be a number of negative consequences:
> >
> > - no lock-after-destroy races
> > - no races between lock/unlock and a subsequent destory
> > - no racy use-after-free detection for destroy vs free
> > - incorrect stack trace for a mutex that happened to reuse the address later
> > - resource leaks for mutexes
> > - no reporting of unlock of locked mutex
> > - no auto-unlock for destroyed mutexes, which will look like the thread is taking infinite number of locks recursively, which will quickly check-fail in deadlock detector
>
>
> Why is that not an issue for pthread mutexes with static initialization and no destruction?


Because these are not destroyed at all. So any problems related to destruction are not problems.
Here we have mutexes that are destroyed, but destructor is not called.


Repository:
  rCXX libc++

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https://reviews.llvm.org/D64299