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Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision

From: Florian Weimer <fweimer at redhat dot com>
To: Torvald Riegel <triegel at redhat dot com>
Cc: munroesj at linux dot vnet dot ibm dot com, Rajalakshmi Srinivasaraghavan <raji at linux dot vnet dot ibm dot com>, libc-alpha at sourceware dot org, aaron Sawdey <acsawdey at linux dot vnet dot ibm dot com>, Ulrich Weigand <Ulrich dot Weigand at de dot ibm dot com>, Steve Munroe <sjmunroe at us dot ibm dot co>, carlos at redhat dot com, adhemerval dot zanella at linaro dot org, adconrad at ubuntu dot com, wschmidt at linux dot vnet dot ibm dot com
Date: Tue, 22 Nov 2016 16:02:25 +0100
Subject: Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
Authentication-results: sourceware.org; auth=none
References: <f777eebe-4a7b-87d2-1281-ab605c7fce8b@linux.vnet.ibm.com> <1479394010.7146.1154.camel@localhost.localdomain> <1479771736.9880.42.camel@oc7878010663> <1479804279.7146.1280.camel@localhost.localdomain> <a5e57060-b0e0-3156-5fdd-da24a4447a5d@redhat.com> <1479807670.7146.1295.camel@localhost.localdomain> <e649d9d8-1711-fa6b-b075-7dfdaf0c18d4@redhat.com> <1479822346.7146.1313.camel@localhost.localdomain>

On 11/22/2016 02:45 PM, Torvald Riegel wrote:

Lock elision relies on this kind of mixed access.  While it would be
nice to have a common formal model for the various HTMs out there from
the perspective of a C11/C++11 memory model setting, I don't think it's
a big problem right now that we don't (AFAIK) have such a formal model.
Lock elision should be well understood, so I'm not worried about any
surprises regarding this use case.

You are the expert. I'm just surprised we embrace a wild-west approachto P&C again, while trying to convince others to argue from thedefinitions instead based on gut feeling.

That being said, I'm don't have a strong opinion regarding the style touse in this case.


Thanks,
Florian

Follow-Ups:
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Torvald Riegel

References:
- BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Rajalakshmi Srinivasaraghavan
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Torvald Riegel
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Steven Munroe
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Torvald Riegel
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Florian Weimer
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Torvald Riegel
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Florian Weimer
- Re: BZ 20822 :powerpc: race condition in __lll_unlock_elision
  - From: Torvald Riegel

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