On 5/13/21 8:56 PM, Connor Davis wrote:
> Callers of dbgp_reset_prep treat a 0 return value as "stop using
> the debug port", which means they don't make any subsequent calls to
> dbgp_reset_prep or dbgp_external_startup.
>
> To ensure the callers' interpretation is correct, first return -EPERM
> from xen_dbgp_op if !xen_initial_domain(). This ensures that
> both xen_dbgp_reset_prep and xen_dbgp_external_startup return 0
> iff the PHYSDEVOP_DBGP_RESET_{PREPARE,DONE} hypercalls succeed. Also
> update xen_dbgp_reset_prep and xen_dbgp_external_startup to return
> -EPERM when !CONFIG_XEN_DOM0 for consistency.
>
> Next, return nonzero from dbgp_reset_prep if xen_dbgp_reset_prep returns
> 0. The nonzero value ensures that callers of dbgp_reset_prep will
> subsequently call dbgp_external_startup when it is safe to do so.
>
> Also invert the return values from dbgp_external_startup for
> consistency with dbgp_reset_prep (this inversion has no functional
> change since no callers actually check the value).
>
> Signed-off-by: Connor Davis <connojdavis@xxxxxxxxx>
For Xen bits:
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
For the rest it seems to me that error code passing could be improved: if it's 0 or 1 it should be bool. Or pass actual error code, with zero for no-error case, such as ...
> ---
> drivers/usb/early/ehci-dbgp.c | 9 ++++++---
> drivers/xen/dbgp.c | 2 +-
> include/linux/usb/ehci-dbgp.h | 14 +++++++++-----
> 3 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
> index 45b42d8f6453..ff993d330c01 100644
> --- a/drivers/usb/early/ehci-dbgp.c
> +++ b/drivers/usb/early/ehci-dbgp.c
> @@ -970,8 +970,8 @@ int dbgp_reset_prep(struct usb_hcd *hcd)
> int ret = xen_dbgp_reset_prep(hcd);
> u32 ctrl;
>
> - if (ret)
> - return ret;
> + if (!ret)
> + return 1;
... here or ...
>
> dbgp_not_safe = 1;
> if (!ehci_debug)
> @@ -995,7 +995,10 @@ EXPORT_SYMBOL_GPL(dbgp_reset_prep);
>
> int dbgp_external_startup(struct usb_hcd *hcd)
> {
> - return xen_dbgp_external_startup(hcd) ?: _dbgp_external_startup();
> + if (!xen_dbgp_external_startup(hcd))
> + return 1;
... here.
-boris
