[+cc Ilpo] On Tue, May 28, 2024 at 02:42:00PM +0800, Bitao Hu wrote: > "present" and "link_active" can be 1 if the status is ready, and 0 if > it is not. Both of them can be -ENODEV if reading the config space > of the hotplug port failed. That's typically the case if the hotplug > port itself was hot-removed. Therefore, this situation can occur: > pciehp_card_present() may return 1 and pciehp_check_link_active() > may return -ENODEV because the hotplug port was hot-removed in-between > the two function calls. In that case we'll emit both "Card present" > *and* "Link Up" since both 1 and -ENODEV are considered "true". This > is not the expected behavior. Those messages should be emited when > "present" and "link_active" are positive. > > Signed-off-by: Bitao Hu <yaoma@xxxxxxxxxxxxxxxxx> > Reviewed-by: Lukas Wunner <lukas@xxxxxxxxx> > --- > v1 -> v2: > 1. Explain the rationale of the code change in the commit message > more clearly. > 2. Add the "Reviewed-by" tag of Lukas. > --- > drivers/pci/hotplug/pciehp_ctrl.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c > index dcdbfcf404dd..6adfdbb70150 100644 > --- a/drivers/pci/hotplug/pciehp_ctrl.c > +++ b/drivers/pci/hotplug/pciehp_ctrl.c > @@ -276,10 +276,10 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) > case OFF_STATE: > ctrl->state = POWERON_STATE; > mutex_unlock(&ctrl->state_lock); > - if (present) > + if (present > 0) I completely agree that this is a problem and this patch addresses it. But ... It seems a little bit weird to me that we even get to this switch statement if we got -ENODEV from either pciehp_card_present() or pciehp_check_link_active(). If that happens, a config read failed, but we're going to go ahead and call pciehp_enable_slot(), which is going to do a bunch more config accesses, potentially try to power up the slot, etc. If a config read failed, it seems like we might want to avoid doing some of this stuff. > ctrl_info(ctrl, "Slot(%s): Card present\n", > slot_name(ctrl)); > - if (link_active) > + if (link_active > 0) > ctrl_info(ctrl, "Slot(%s): Link Up\n", > slot_name(ctrl)); These are cases where we misinterpreted -ENODEV as "device is present" or "link is active". pciehp_ignore_dpc_link_change() and pciehp_slot_reset() also call pciehp_check_link_active(), and I think they also interpret -ENODEV as "link is active". Do we need similar changes there? > ctrl->request_result = pciehp_enable_slot(ctrl); > -- > 2.37.1 (Apple Git-137.1) >
