Messages in this thread | | | Date | Tue, 17 Feb 2009 22:45:18 +0100 | From | Oleg Nesterov <> | Subject | Re: Q: smp.c && barriers (Was: [PATCH 1/4] generic-smp: remove single ipi fallback for smp_call_function_many()) |
| |
On 02/17, Paul E. McKenney wrote: > > On Tue, Feb 17, 2009 at 08:28:10PM +0100, Oleg Nesterov wrote: > > > > So the question is: is there any arch which surely needs this barrier? > > > > IOW, > > int COND; > > > > void smp_xxx_interrupt(regs) > > { > > BUG_ON(!COND); > > } > > > > COND = 1; > > mb(); > > smp_send_xxx(cpu); > > > > can we really hit the BUG_ON() above on some arch? > > If all of the above is executed by the same task, tripping the BUG_ON() > means either a compiler or CPU bug.
I think you misunderstood...
smp_send_xxx() sends the ipi to another CPU, and smp_xxx_interrupt() is the handler.
Oleg.
| |