On Wed, Feb 21, 2024 at 12:31:06PM +0100, Markus Armbruster wrote: > Date: Wed, 21 Feb 2024 12:31:06 +0100 > From: Markus Armbruster <arm...@redhat.com> > Subject: Re: [PATCH 1/6] hw/cxl/cxl-host: Fix missing ERRP_GUARD() in > cxl_fixed_memory_window_config() > > Zhao Liu <zhao1....@linux.intel.com> writes: > > > From: Zhao Liu <zhao1....@intel.com> > > > > As the comment in qapi/error, dereferencing @errp requires > > ERRP_GUARD(): > > > > * = Why, when and how to use ERRP_GUARD() = > > * > > * Without ERRP_GUARD(), use of the @errp parameter is restricted: > > * - It must not be dereferenced, because it may be null. > > * - It should not be passed to error_prepend() or > > * error_append_hint(), because that doesn't work with &error_fatal. > > * ERRP_GUARD() lifts these restrictions. > > * > > * To use ERRP_GUARD(), add it right at the beginning of the function. > > * @errp can then be used without worrying about the argument being > > * NULL or &error_fatal. > > * > > * Using it when it's not needed is safe, but please avoid cluttering > > * the source with useless code. > > > > Currently, since machine_set_cfmw() - the caller of > > cxl_fixed_memory_window_config() - doesn't get the NULL errp parameter > > as the "set" method of object property, cxl_fixed_memory_window_config() > > doesn't trigger the dereference issue. > > > > To follow the requirement of errp, add missing ERRP_GUARD() in > > cxl_fixed_memory_window_config(). > > > > Suggested-by: Markus Armbruster <arm...@redhat.com> > > Signed-off-by: Zhao Liu <zhao1....@intel.com> > > --- > > Suggested by credit: > > Markus: Referred his explanation about ERRP_GUARD(). > > --- > > hw/cxl/cxl-host.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/hw/cxl/cxl-host.c b/hw/cxl/cxl-host.c > > index 2aa776c79c74..c5f5fcfd64d0 100644 > > --- a/hw/cxl/cxl-host.c > > +++ b/hw/cxl/cxl-host.c > > @@ -26,6 +26,7 @@ static void cxl_fixed_memory_window_config(CXLState > > *cxl_state, > > CXLFixedMemoryWindowOptions > > *object, > > Error **errp) > > { > > + ERRP_GUARD(); > > g_autofree CXLFixedWindow *fw = g_malloc0(sizeof(*fw)); > > strList *target; > > int i; > > The dereferences are > > fw->enc_int_ways = cxl_interleave_ways_enc(fw->num_targets, errp); > if (*errp) { > return; > } > > and > > fw->enc_int_gran = > cxl_interleave_granularity_enc(object->interleave_granularity, > errp); > if (*errp) { > return; > } > > We check *errp, because neither function returns a suitable error code. > > Reviewed-by: Markus Armbruster <arm...@redhat.com> >
Thanks! I'll attach your description to the commit message. Regards, Zhao