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Re: [PATCHv3] PowerPC: Fix a race condition when eliding a lock
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Tulio Magno Quites Machado Filho <tuliom at linux dot vnet dot ibm dot com>, adhemerval dot zanella at linaro dot org
- Cc: triegel at redhat dot com, libc-alpha at sourceware dot org, munroesj at linux dot vnet dot ibm dot com
- Date: Mon, 24 Aug 2015 14:58:24 -0400
- Subject: Re: [PATCHv3] PowerPC: Fix a race condition when eliding a lock
- Authentication-results: sourceware.org; auth=none
- References: <55D742D3 dot 9050600 at redhat dot com> <1440439895-11812-1-git-send-email-tuliom at linux dot vnet dot ibm dot com>
On 08/24/2015 02:11 PM, Tulio Magno Quites Machado Filho wrote:
> Changes since v2:
> - Moved part of the source code comments to the commit message.
> - Added O'Donnel's suggestion to the source code comments.
>
> Changes since v1:
> - Improved commit message.
> - Added new comments in the source code alerting to the concurrency details
> intrinsic to this code.
> - Removed compiler barriers from this patch, which will be treated in another
> patch and will be synchronized with the GCC implementation.
> + if (__builtin_tbegin (0)) \
> + { \
> + if (is_lock_free) \
> + { \
> + ret = 1; \
> + break; \
> + } \
> + __builtin_tabort (_ABORT_LOCK_BUSY); \
> + } \
> + else \
> + if (!__get_new_count(&adapt_count)) \
> + break; \
Toravld still suggests an atomic_load_relaxed here:
https://www.sourceware.org/ml/libc-alpha/2015-08/msg00893.html
Is there any technical objection to that request?
It does highlight, as he notes, the transactional and non-transactional
accesses for that evaluated value.
Cheers,
Carlos.