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Re: [PATCH v3 1/2] hw/nvme: fix incorrect use of errp/local_err
From: |
Markus Armbruster |
Subject: |
Re: [PATCH v3 1/2] hw/nvme: fix incorrect use of errp/local_err |
Date: |
Fri, 11 Nov 2022 07:55:24 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) |
Klaus Jensen <its@irrelevant.dk> writes:
> 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.
Happens :)
If you have suggestions on improving the doc, shoot.
This commit's message could perhaps be adjusted like
hw/nvme: Clean up confused use of errp/local_err
Remove an unnecessary local Error value in nvme_realize(). In the
process, change nvme_check_constraints() to return a bool.
What do you think?