Re: [PATCH v3 1/2] hw/nvme: fix incorrect use of errp/local_err

[Klaus Jensen <its@irrelevant.dk>]

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On Nov 11 07:36, Markus Armbruster wrote:
> Klaus Jensen <its@irrelevant.dk> writes:
> 
> > From: Klaus Jensen <k.jensen@samsung.com>
> >
> > Remove an unnecessary local Error value in nvme_realize(). In the
> > process, change nvme_check_constraints() into returning a bool.
> >
> > Finally, removing the local Error value also fixes a bug where an error
> > returned from nvme_init_subsys() would be lost.
> 
> Would it be lost?  It's the hunk below:
> 
> > Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> > ---
> >  hw/nvme/ctrl.c | 48 +++++++++++++++++++++++-------------------------
> >  1 file changed, 23 insertions(+), 25 deletions(-)
> >
> > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> > index ac3885ce5079..a5c0a5fa6ce2 100644
> > --- a/hw/nvme/ctrl.c
> > +++ b/hw/nvme/ctrl.c
> 
> [...]
> 
> > @@ -7586,7 +7585,6 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp)
>    static void nvme_realize(PCIDevice *pci_dev, Error **errp)
>    {
>        NvmeCtrl *n = NVME(pci_dev);
>        NvmeNamespace *ns;
>        Error *local_err = NULL;
> 
> @local_err is null.
> 
>        NvmeCtrl *pn = NVME(pcie_sriov_get_pf(pci_dev));
> 
>        if (pci_is_vf(pci_dev)) {
>            /*
>             * VFs derive settings from the parent. PF's lifespan exceeds
>             * that of VF's, so it's safe to share params.serial.
>             */
>            memcpy(&n->params, &pn->params, sizeof(NvmeParams));
>            n->subsys = pn->subsys;
>        }
> 
>        nvme_check_constraints(n, &local_err);
>        if (local_err) {
>            error_propagate(errp, local_err);
>            return;
>        }
> 
> @local_err still is null.
> 
>        qbus_init(&n->bus, sizeof(NvmeBus), TYPE_NVME_BUS,
> >                &pci_dev->qdev, n->parent_obj.qdev.id);
> >  
> >      if (nvme_init_subsys(n, errp)) {
> > -        error_propagate(errp, local_err);
> 
> Since @local_err is null, this error_propagate() does nothing.  The
> error from nvme_init_subsys() remains in @errp.
> 

Oh, right. Thanks.

I misread the function documentation, getting the impression that it
would overwrite dst_errp regardless of the value of local_err.

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