On 2013/7/29 20:13, Peter Zijlstra wrote: > On Mon, Jul 29, 2013 at 10:29:45AM +0800, Xie XiuQi wrote: >> We used csd_flags formerly because we allocated csd_data by >> kmalloc when "wait == 0". When fail to allocation, we will >> fall back to on-stack allocation. "csd_data" might be invalid >> after generic_exec_single return. >> >> But now we use per cpu data for single cpu ipi calls, and >> csd_data can't fall back to on-stack allocation when "wait == 0". >> >> So csd_flags is unnecessary now. Remove it. > > The much simpler argument is that both callsites of > generic_exec_single() do an unconditional csd_lock(). >
That's right. All csd_data are protected by csd_lock. >> Signed-off-by: Xie XiuQi <xiexi...@huawei.com> >> --- >> kernel/smp.c | 11 +---------- >> 1 files changed, 1 insertions(+), 10 deletions(-) >> >> diff --git a/kernel/smp.c b/kernel/smp.c >> index 4dba0f7..cac2b6e 100644 >> --- a/kernel/smp.c >> +++ b/kernel/smp.c >> @@ -186,25 +186,16 @@ 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; >> - >> csd->func(csd->info); >> >> /* >> * Unlocked CSDs are valid through generic_exec_single(): >> */ >> - if (csd_flags & CSD_FLAG_LOCK) >> - csd_unlock(csd); >> + csd_unlock(csd); > > The comment is completely useless and confusing after this; why do you > leave it in? > Thanks for your comment, I'll remove the comment and send a new version soon. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/