Re: [PATCH 3/4] PCI: endpoint: pci-epf-test: Don't free doorbell IRQ unless requested

[Koichiro Den]

On Mon, Feb 16, 2026 at 12:35:56PM +0100, Niklas Cassel wrote:
> On Mon, Feb 16, 2026 at 12:09:13AM +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 or when request_threaded_irq()
> > failed.
> > 
> > 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@xxxxxxxxxxxxx>
> > ---
> >  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 148a34e51f6b..defe1e2ea427 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;
> 
> It would be nice if we could avoid this, it looks a bit odd.
> 
> 
> >  	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);
> > @@ -732,6 +736,8 @@ static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test,
> >  	size_t offset;
> >  	int ret;
> >  
> > +	epf_test->db_irq_requested = false;
> > +
> >  	ret = pci_epf_alloc_doorbell(epf, 1);
> >  	if (ret)
> >  		goto set_status_err;
> > @@ -751,6 +757,7 @@ static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test,
> >  		goto err_doorbell_cleanup;
> >  	}
> >  
> > +	epf_test->db_irq_requested = true;
> >  	reg->doorbell_data = cpu_to_le32(msg->data);
> >  	reg->doorbell_bar = cpu_to_le32(bar);
> >  
> 
> Can't we do something like:
> 
> -For all goto's after request_threaded_irq() success case:
> jump to a label that also cleans up the IRQ.
> 
> For failures before or at request_threaded_irq(), jump to
> a label that does not call free_irq().

I thought this would be a minimal change to avoid the problematic case, but I
agree it's not very clean (the "db_irq_requested" flag looks a bit odd).

So I'll split pci_epf_test_doorbell_cleanup() into two helper functions to match
your suggested structure.

> 
> 
> 
> pci_epf_test_disable_doorbell() should probably return error
> if (!epf_test->db_bar.size)
> 
> (before pci_epf_test_disable_doorbell() calls free_irq())
> 
> pci_epf_test_disable_doorbell() should probably also memset
> epf_test->db_bar.

and I'll take care of these suggestions as well.

Thanks for the review,
Koichiro

> 
> 
> Kind regards,
> Niklas