Re: [PATCH] PCI: endpoint: pci-epf-vntb: Check pci_epc_get_features() return value

[Niklas Cassel <cassel@kernel.org>]

On Tue, Feb 24, 2026 at 05:31:03AM -0800, Alok Tiwari wrote:
> pci_epc_get_features() may return NULL for invalid function numbers or
> if the EPC driver does not provide feature information. Other EPF drivers
> such as pci-epf-ntb.c and pci-epf-test.c already handle this case.
> 
> Add a defensive NULL check to avoid a potential NULL pointer dereference.
> 
> No functional change intended.
> 
> Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>

I think a better solution is to do like pci-epf-test.c, which calls
pci_epc_get_features() once in .bind() and if it fails, it fails bind(),
if it returns non-NULL, it caches the result:
https://github.com/torvalds/linux/blob/v6.19/drivers/pci/endpoint/functions/pci-epf-test.c#L1112-L1123

That way, all other functions do not need to NULL check
pci_epc_get_features(). (Instead it can use the cached value)

pci-epf-vntb.c should probably do something similar to avoid sprinkling
NULL checks all over pci-epf-vntb.c.

And, if there are any existing
if (!epc_features) return -EINVAL;

they can be removed once you've added the check in .bind().


Kind regards,
Niklas