Messages in this thread | | | Date | Sat, 6 Jul 2013 13:45:53 +0800 | From | Wang YanQing <> | Subject | Re: [PATCH 3/3] smp/ipi:Remove check around csd lock in handler for smp_call_function variants |
| |
On Fri, Jul 05, 2013 at 09:57:21PM +0530, Preeti U Murthy wrote: > call_single_data is always locked by all callers of > arch_send_call_function_single_ipi() or > arch_send_call_function_ipi_mask() which results in execution of > generic_call_function_interrupt() handler. > > Hence remove the check for lock on csd in generic_call_function_interrupt() > handler, before unlocking it.
I can't find where is the generic_call_function_interrupt :)
> Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> > Cc: srivatsa.bhat@linux.vnet.ibm.com > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Rusty Russell <rusty@rustcorp.com.au > --- > > kernel/smp.c | 14 +------------- > 1 file changed, 1 insertion(+), 13 deletions(-) > > diff --git a/kernel/smp.c b/kernel/smp.c > index b6981ae..d37581a 100644 > --- a/kernel/smp.c > +++ b/kernel/smp.c > @@ -181,25 +181,13 @@ void generic_smp_call_function_single_interrupt(void) > > while (!list_empty(&list)) { > struct call_single_data *csd; > - unsigned int csd_flags; > > csd = list_entry(list.next, struct call_single_data, list); > list_del(&csd->list); > > - /* > - * 'csd' can be invalid after this call if flags == 0 > - * (when called through generic_exec_single()), > - * so save them away before making the call: > - */ > - csd_flags = csd->flags; > -
You haven't mention this change in the ChangeLog, don't do it. I can't see any harm to remove csd_flags, but I hope others check it again.
> csd->func(csd->info); > > - /* > - * Unlocked CSDs are valid through generic_exec_single(): > - */ > - if (csd_flags & CSD_FLAG_LOCK) > - csd_unlock(csd); > + csd_unlock(csd);
I don't like this change, I think check CSD_FLAG_LOCK to make sure we really need csd_unlock is good.
Just like you can't know who and how people will use the API, so some robust check code is good.
| |