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

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 <[email protected]>
> > ---
> >  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.

The reason I didn't include the fix in this series, even though I added
Patch #6 and #7, is mainly about how those relate to Patch #8. The
doorbell_offset issue feels orthogonal to Patch #8 to me.

- the issue addressed by Patch #6 is more likely to be hit once Patch #8 is
  applied, depending on the platform, compared to the existing MSI
  doorbell-only setup.
- without Patch #7, Patch #8 could silently mask the issue, which might
  make it look like it includes unrelated changes. I felt that keeping the
  fix separate from the functional change would make the series clearer and
  easier to reason about, so I added Patch #7.
  
If there are no objections from either of you, I'm happy to include a fix
patch for this in v7.

Best regards,
Koichiro

> 
> 
> 
> Kind regards,
> Niklas