On Fri, Nov 21, 2003 at 03:23:09PM -0700, Stuart Macdonald wrote: > >>On Wed, 2003-11-05 at 01:51, Yao, Zhigang(Richard) wrote: > >> Hi, > >> > >> I want to do the atomic operation ( such as i++ ) in user space, can I > copy > >> and include include/XXX/atomic.h directly? > > >the answer is no. If you do that the operations aren't guaranteed to be > >atomic (and probably arent even on x86) > > >However glibc has primitives for this instead, as do helper libraries > >like apr etc etc > > Setting aside portability issue, the primatives in > /include/asm-i386/atomic.h result in IA32 instructions (lock incl) > which lock the bus around the inc instruction so the operation will in-fact > be atomic - right? if you look careful you'll see that it will only use lockl if CONFIG_SMP is set. Which may be the case on your box... or not. -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
