Re: PR/49816 CVS commit: src/libexec/ld.elf_so

[Masao Uebayashi <uebayasi%gmail.com@localhost>]

The following reply was made to PR lib/49816; it has been noted by GNATS.

From: Masao Uebayashi <uebayasi%gmail.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: lib-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
	YAMAMOTO Takashi <yamt%netbsd.org@localhost>
Subject: Re: PR/49816 CVS commit: src/libexec/ld.elf_so
Date: Wed, 8 Apr 2015 12:42:28 +0900

 >  I don't think that's relevant, this is about global visiblity of
 >  changes. E.g. if another thread tries to get the mutex, it must see all
 >  changes from the current thread when successfully acquired the mutex.
 >
 >  Joerg
 
 I can't follow... Your first message was:
 
 > None of those should matter on amd64? CAS has an implicit total memory
 > barrier, so this seems to just add a lot of overhead for no reason.
 
 If you're talking about atomic vs. memory barrier, isn't it something
 addressed by the new C11 atomic API?  Kernel mutex code has
 MUTEX_RECEIVE()/MUTEX_GIVE() for that purpose (IIUC).