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Re: [PATCHv4] powerpc: Fix write-after-destroy in lock elision
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: tuliom at linux dot vnet dot ibm dot com (Tulio Magno Quites Machado Filho)
- Cc: triegel at redhat dot com, libc-alpha at sourceware dot org, adhemerval dot zanella at linaro dot org, raji at linux dot vnet dot ibm dot com, munroesj at linux dot vnet dot ibm dot com
- Date: Wed, 11 Jan 2017 16:22:01 +0100 (CET)
- Subject: Re: [PATCHv4] powerpc: Fix write-after-destroy in lock elision
- Authentication-results: sourceware.org; auth=none
Tulio Magno Quites Machado Filho wrote:
> + /* Update adapt_count in the critical section to prevent a
> + write-after-destroy error as mentioned in BZ 20822. The
> + following update of adapt_count has to be contained within
> + the critical region of the fall-back lock in order to not violate
> + the mutex destruction requirements. */
> + short __tmp = atomic_load_relaxed (adapt_count);
> + if (__tmp > 0)
> + atomic_store_relaxed (adapt_count, __tmp--);
Doesn't this have to be --__tmp to have any effect?
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU/Linux compilers and toolchain
Ulrich.Weigand@de.ibm.com