On Wed, Dec 4, 2013 at 9:46 AM, Christoph Hellwig <h...@infradead.org> wrote: > While doing my recent work on the generic smp function calls I noticed > that smp_call_function_single without the wait flag can't work, as > it allocates struct call_single_data on stack, and without the wait > flag will happily return before the IPI has been executed.
I don't understand the problem yet. With wait==0, smp_call_function_single() sets "csd = &__get_cpu_var(csd_data)", so it's not using a struct on the stack. We'll queue up "func" and likely will return before it is executed, but that should be fine because nobody will overwrite csd_data until it *is* executed and csd_unlock() has been called. > This affects the following callers: > > arch/ia64/kernel/mca.c:mca_cpu_callback() > arch/ia64/kernel/smpboot.c:ia64_sync_itc() > arch/x86/kernel/kvm.c:kvm_cpu_notify() > arch/x86/oprofile/nmi_int.c:oprofile_cpu_notifier() > arch/x86/pci/amd_bus.c:amd_cpu_notify() I don't see any reason why amd_cpu_notify() needs to use wait==0. > drivers/staging/octeon/ethernet-rx.c:cvm_oct_enable_one_cpu() > kernel/stop_machine.c:stop_two_cpus() > > It would be good to get these fixed so that we could remove the > parameter. Either convert them to wait, or use a preallocated > call_single_data and __smp_call_function_single. > > After that I'd like to remove the wait argument to prevent further > abuses. -- 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/
