Disable all lock elision unless --enable-lock-elision=yes

[Carlos O'Donell]

On 09/27/2014 02:10 PM, Andi Kleen wrote:
> Hi Carlos,
> 
> On Sat, Sep 27, 2014 at 12:40:28AM -0400, Carlos O'Donell wrote:
>> Andi.
>>
>> The rwlock elision support you added in 2014-06-13
>> appears to unconditionally enable elision for rwlock's
>> if the RTM-bit indicates TSX is present. That isn't what
>> we do for mutexes, and isn't very conservative in that
>> case.
>>
>> Did I read the code right?
> 
> You're right. It should have been disabled in this case.
> 
> Patch looks good to me.

Andi,

Thanks. I'll get that checked in shortly. I just wanted to make
sure that we weren't doing it for any other reason.

I'll adjust the wording of the configure switch to indicate it
is for all elision usage in the library.

Cheers,
Carlos.