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Date: Wed, 5 Jul 2017 08:30:14 +0200
From: Jens Gustedt <jens.gustedt@...ia.fr>
To: musl@...ts.openwall.com
Subject: move to a proper __lock_t type

Hello,

On Tue, 4 Jul 2017 18:28:42 -0400 Rich Felker <dalias@...c.org> wrote:

> On Wed, Jul 05, 2017 at 01:24:23AM +0300, Alexander Monakov wrote:
> > On Tue, 4 Jul 2017, Rich Felker wrote:
> >   
> > > Thanks, applying.  
> > 
> > Can you please document the rationale for using bare ints instead
> > of an explicit struct for internal locks?  
> 
> I don't think there was/is any good one, it was just the choice that
> was made at the time. At one point there might have been places it
> avoided need for including a header to define the type, or where being
> explicit about the storage needed for the lock mattered (think stdio
> FILE layout, but it uses its own lock anyway), but I think it was
> mostly unjustified. I wouldn't be opposed to changing it.

So what would you think of the following migration path:

 (1) Finish the volatile/atomic cleanup by adding a_load, a_load_l and
 perhaps corresponding store primitives.

 (2) Replace all occurences of "volatile int[2]" by "__lock_t" that
 encapsulates just that in a struct.

 (3) Replace the __lock/__unlock pair by the new algorithm

 (4) Reduce "__lock_t" to a struct that simply has a "volatile int" as
 sole member.

In all of that, would we need the "__" in the name of the structure? I
think this name will never be exported.

Jens

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