Re: [PATCH net v2 3/4] net: mana: Don't overwrite port probe error with add_adev result

Simon Horman
2026-04-15T12:37:14Z

On Wed, Apr 15, 2026 at 12:04:51AM -0700, Erni Sri Satya Vennela wrote:
> On Tue, Apr 14, 2026 at 04:35:03PM +0100, Simon Horman wrote:
> > From: 'Simon Horman' <horms@kernel.org>
> >
> > This is an AI-generated review of your patch. The human sending this
> > email has considered the AI review valid, or at least plausible.
> > Full review at: https://sashiko.dev
> > ---
> > net: mana: Don't overwrite port probe error with add_adev result
> >
> > This commit ensures that if mana_probe_port() or mana_attach() fails, the
> > error is not overwritten by the result of add_adev(). By preserving the
> > error, it triggers mana_remove() cleanup instead of leaving ports partially
> > initialized.
> >
> > > diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > > index 9d095a6fb56c7..4d42cbfb3f15b 100644
> > > --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> > > +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> > > @@ -3634,10 +3634,9 @@ int mana_probe(struct gdma_dev *gd, bool resuming)
> > > if (!resuming) {
> > > for (i = 0; i < ac->num_ports; i++) {
> > > err = mana_probe_port(ac, i, &ac->ports[i]);
> > > - /* we log the port for which the probe failed and stop
> > > - * probes for subsequent ports.
> > > - * Note that we keep running ports, for which the probes
> > > - * were successful, unless add_adev fails too
> > > + /* Log the port for which the probe failed, stop probing
> > > + * subsequent ports, and skip add_adev.
> > > + * Already-probed ports remain functional.
> > > */
> >
> > Are these comments accurate regarding ports remaining functional?
> >
> > Since this patch preserves the error code, execution falls through to the end
> > of mana_probe() where it checks if err is set and calls mana_remove().
> > mana_remove() will iterate over the successfully allocated ports, completely
> > detach them, unregister their net_devices, and destroy event queues.
> >
> > It appears no ports remain functional because the device is completely torn
> > down.
> >
> I will update the patch with the updated comment message.

Thanks.

> > [ ... ]
> >
> > > @@ -3651,10 +3650,9 @@ int mana_probe(struct gdma_dev *gd, bool resuming)
> > > enable_work(&apc->queue_reset_work);
> > > err = mana_attach(ac->ports[i]);
> > > rtnl_unlock();
> > > - /* we log the port for which the attach failed and stop
> > > - * attach for subsequent ports
> > > - * Note that we keep running ports, for which the attach
> > > - * were successful, unless add_adev fails too
> > > + /* Log the port for which the attach failed, stop
> > > + * attaching subsequent ports, and skip add_adev.
> > > + * Already-attached ports remain functional.
> > > */
> > > if (err) {
> > > dev_err(dev, "Attach Failed for port %d\n", i);
> > > @@ -3663,7 +3661,8 @@ int mana_probe(struct gdma_dev *gd, bool resuming)
> >
> > Does propagating this error during PM resume introduce a NULL pointer
> > dereference?
> >
> > If PM resume fails here (resuming == true), the preserved error code causes
> > mana_probe() to call mana_remove(), which tears down the device and sets
> > gd->gdma_context = NULL.
> >
> > However, a failed resume callback does not automatically unbind the driver.
> > When the device is eventually unbound later, mana_remove() is invoked again:
> >
> > drivers/net/ethernet/microsoft/mana/mana_en.c:mana_remove() {
> > struct gdma_context *gc = gd->gdma_context;
> > struct device *dev = gc->dev;
> > ...
> > }
> >
> > In the second invocation, gd->gdma_context is NULL, meaning gc is NULL,
> > which could lead to a kernel panic when dereferencing gc->dev.
>
> Thankyou for pointing it out, Simon.
> Since this is a pre-existing bug, I will create a different patch for
> this change and make it as part of this patchset.

Likewise, thanks.

FTR, it it is a pre-existing bug then I don't think it needs
to block progress of your patchset. Even if fixing things
sooner than later is a good maxim.