On Wed, 15 Jun 2016 22:26:41 +0200 Greg Kurz <[email protected]> wrote:
> A strange behaviour is observed when comparing PCI hotplug in QEMU, between > x86 and pseries. If you consider the following steps: > - start a VM > - add a PCI device via the QEMU monitor before the rtasd has started (for > example starting the VM in paused state, or hotplug during FW or boot > loader) > - resume the VM execution > > The x86 kernel detects the PCI device, but the pseries one does not. > > This happens because the rtasd kernel worker is currently started under > device_initcall, while PCI probing happens earlier under subsys_initcall. > > As a consequence, if we have a pending RTAS event at boot time, a message > is printed and the event is dropped. > > This patch moves all the initialization of rtasd to arch_initcall, which is > run before subsys_call: this way, logging_enabled is true when the RTAS > event pops up and it is not lost anymore. > > The proc fs bits stay at device_initcall because they cannot be run before > fs_initcall. > > Signed-off-by: Greg Kurz <[email protected]> > --- > v2: - avoid behaviour change: don't create the proc entry if early init failed > I forgot to mention that Thomas had sent a Tested-by for v1, which I think is still valid for v2. > Michael, > > This was also tested under PowerVM: it doesn't fix anything there because the > HMC tells it won't honor DLPAR features as long as the RMC isn't here, which > happens later in the boot sequence. It hence seems impossible to have a > pending > RTAS event at boot time. > > It doesn't seem to break anything either, the kernel boots and hotplug works > okay once the RMC is up. > > Cheers. > > -- > Greg > > --- > arch/powerpc/kernel/rtasd.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c > index e864b7c5884e..a26a02006576 100644 > --- a/arch/powerpc/kernel/rtasd.c > +++ b/arch/powerpc/kernel/rtasd.c > @@ -526,10 +526,8 @@ void rtas_cancel_event_scan(void) > } > EXPORT_SYMBOL_GPL(rtas_cancel_event_scan); > > -static int __init rtas_init(void) > +static int __init rtas_event_scan_init(void) > { > - struct proc_dir_entry *entry; > - > if (!machine_is(pseries) && !machine_is(chrp)) > return 0; > > @@ -562,13 +560,27 @@ static int __init rtas_init(void) > return -ENOMEM; > } > > + start_event_scan(); > + > + return 0; > +} > +arch_initcall(rtas_event_scan_init); > + > +static int __init rtas_init(void) > +{ > + struct proc_dir_entry *entry; > + > + if (!machine_is(pseries) && !machine_is(chrp)) > + return 0; > + > + if (!rtas_log_buf) > + return -ENODEV; > + > entry = proc_create("powerpc/rtas/error_log", S_IRUSR, NULL, > &proc_rtas_log_operations); > if (!entry) > printk(KERN_ERR "Failed to create error_log proc entry\n"); > > - start_event_scan(); > - > return 0; > } > __initcall(rtas_init); > >
