lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 27 Jun 2013 03:06:58 +0200 From: Andi Kleen <andi@...stfloor.org> To: Waiman Long <waiman.long@...com> Cc: Andi Kleen <andi@...stfloor.org>, Alexander Viro <viro@...iv.linux.org.uk>, Jeff Layton <jlayton@...hat.com>, Miklos Szeredi <mszeredi@...e.cz>, Ingo Molnar <mingo@...hat.com>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, Linus Torvalds <torvalds@...ux-foundation.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, "Chandramouleeswaran, Aswin" <aswin@...com>, "Norton, Scott J" <scott.norton@...com> Subject: Re: [PATCH v2 1/2] spinlock: New spinlock_refcount.h for lockless update of refcount > In the uncontended case, doing spin_unlock_wait will be similar to > spin_can_lock. This, when combined with a cmpxchg, is still faster > than doing 2 atomic operations in spin_lock/spin_unlock. I'm totally against any new users of spin_unlock_wait() It has bizarre semantics, most likely will make various lock optimizations impossible, it's race condition hell for most users etc. spin_can_lock() is not quite as bad has a lot of the similar problems. > BTW, spin_can_lock is just the negation of spin_is_locked. e.g. with elision it's not. -Andi -- ak@...ux.intel.com -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists