Re: [PATCH v6 6/8] PCI: endpoint: pci-epf-test: Don't free doorbell IRQ unless requested

[Niklas Cassel <cassel@kernel.org>]

On Tue, Feb 10, 2026 at 10:54:20PM +0900, Koichiro Den wrote:
> On Tue, Feb 10, 2026 at 01:36:29PM +0100, Niklas Cassel wrote:
> > On Mon, Feb 09, 2026 at 09:53:14PM +0900, Koichiro Den wrote:
> > > pci_epf_test_enable_doorbell() allocates a doorbell and then installs
> > > the interrupt handler with request_threaded_irq(). On failures before
> > > the IRQ is successfully requested (e.g. no free BAR,
> > > request_threaded_irq() failure), the error path jumps to
> > > err_doorbell_cleanup and calls pci_epf_test_doorbell_cleanup().
> > > 
> > > pci_epf_test_doorbell_cleanup() unconditionally calls free_irq() for the
> > > doorbell virq, which can trigger "Trying to free already-free IRQ"
> > > warnings when the IRQ was never requested.
> > > 
> > > Track whether the doorbell IRQ has been successfully requested and only
> > > call free_irq() when it has.
> > > 
> > > Fixes: eff0c286aa91 ("PCI: endpoint: pci-epf-test: Add doorbell test support")
> > > Signed-off-by: Koichiro Den <den@valinux.co.jp>
> > > ---
> > >  drivers/pci/endpoint/functions/pci-epf-test.c | 9 ++++++++-
> > >  1 file changed, 8 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > index 6952ee418622..23034f548c90 100644
> > > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > @@ -86,6 +86,7 @@ struct pci_epf_test {
> > >  	bool			dma_private;
> > >  	const struct pci_epc_features *epc_features;
> > >  	struct pci_epf_bar	db_bar;
> > > +	bool			db_irq_requested;
> > >  	size_t			bar_size[PCI_STD_NUM_BARS];
> > >  };
> > >  
> > > @@ -715,7 +716,10 @@ static void pci_epf_test_doorbell_cleanup(struct pci_epf_test *epf_test)
> > >  	struct pci_epf_test_reg *reg = epf_test->reg[epf_test->test_reg_bar];
> > >  	struct pci_epf *epf = epf_test->epf;
> > >  
> > > -	free_irq(epf->db_msg[0].virq, epf_test);
> > > +	if (epf_test->db_irq_requested && epf->db_msg) {
> > > +		free_irq(epf->db_msg[0].virq, epf_test);
> > > +		epf_test->db_irq_requested = false;
> > > +	}
> > >  	reg->doorbell_bar = cpu_to_le32(NO_BAR);
> > >  
> > >  	pci_epf_free_doorbell(epf);
> > > @@ -741,6 +745,8 @@ static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test,
> > >  	if (bar < BAR_0)
> > >  		goto err_doorbell_cleanup;
> > >  
> > > +	epf_test->db_irq_requested = false;
> > > +
> > >  	ret = request_threaded_irq(epf->db_msg[0].virq, NULL,
> > >  				   pci_epf_test_doorbell_handler, IRQF_ONESHOT,
> > >  				   "pci-ep-test-doorbell", epf_test);
> > 
> > Another bug in pci_epf_test_enable_doorbell():
> > 
> > Since we reuse the BAR size, and use dynamic inbound mapping,
> > what if the returned DB offset is larger than epf->bar[bar].size ?
> > 
> > I think we need something like this before calling pci_epc_set_bar():
> > 
> > if (reg->doorbell_offset >= epf->bar[bar].size)
> >     goto err_doorbell_cleanup;
> 
> Right, I remember this coming up in another thread.
> 
> If there are no objections from either of you, I'm happy to include a fix
> patch for this in v7.

No objection from me.


Ideally I would also like:

	if (!(test->ep_caps & CAP_DYNAMIC_INBOUND_MAPPING))
		return -EOPNOTSUPP;

and that the pci_endpoint_test selftest would return skip on -EOPNOTSUPP,
since the doorbell test currently relies on CAP_DYNAMIC_INBOUND_MAPPING,
but that might make your series too big.


Thus, I'm happy if you add a safety check for:
reg->doorbell_offset >= epf->bar[bar].size


Kind regards,
Niklas