| 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: Wed, 27 Aug 2014 07:50:52 +0000 From: Dexuan Cui <decui@...rosoft.com> To: Jan Beulich <JBeulich@...e.com> CC: "jeremy@...p.org" <jeremy@...p.org>, KY Srinivasan <kys@...rosoft.com>, "chrisw@...s-sol.org" <chrisw@...s-sol.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: sync_set_bit() vs set_bit() -- what's the difference? > -----Original Message----- > From: Jan Beulich > Sent: Wednesday, August 27, 2014 15:39 PM > >>> On 27.08.14 at 09:30, <decui@...rosoft.com> wrote: > > I'm curious about the difference. :-) > > > > sync_set_bit() is only used in drivers/hv/ and drivers/xen/ while set_bit() > > is used in all other places. What makes hv/xen special? > > I guess this would really want to be used by anything communicating > with a hypervisor or a remote driver: set_bit() gets its LOCK prefix > discarded when the local kernel determines it runs on a single CPU > only. Obviously having knowledge of the CPU count inside a VM does > not imply anything about the number of CPUs available to the host, > i.e. stripping LOCK prefixes in that case would be unsafe. > > Jan Thank you, Juergen and Jan for your quick answers! I didn't realize LOCK_PREFIX is "" for UP. :-) Thanks, -- Dexuan -- 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