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 <pre...@linux.vnet.ibm.com>
> Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
> Cc: Ingo Molnar <mi...@elte.hu>
> Cc: Xiao Guangrong <xiaoguangr...@cn.fujitsu.com>
> Cc: srivatsa.b...@linux.vnet.ibm.com
> Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> Cc: Steven Rostedt <rost...@goodmis.org>
> Cc: Rusty Russell <ru...@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.
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