linux-kernel - Re: [RESEND PATCH v1] misc: pci_endpoint_test: Fix irq

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Message-ID: <20250116150412.GA581512@bhelgaas>
Date: Thu, 16 Jan 2025 09:04:12 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v1] misc: pci_endpoint_test: Fix irq_type to
 convey the correct type

On Thu, Jan 16, 2025 at 11:41:45AM +0900, Kunihiko Hayashi wrote:
> There are two variables that indicate the interrupt type to be used
> in the next test execution, global "irq_type" and test->irq_type.
> 
> The former is referenced from pci_endpoint_test_get_irq() to preserve
> the current type for ioctl(PCITEST_GET_IRQTYPE).
> 
> In pci_endpoint_test_request_irq(), since this global variable is
> referenced when an error occurs, the unintended error message is
> displayed.

Apparently this test fails (with an error message) when it shouldn't?
Please include the error message here.

"... since this global variable is referenced ..." is not quite enough
explanation of how this causes a spurious test failure or under what
circumstances the failure occurs.

> And the type set in pci_endpoint_test_set_irq() isn't reflected in
> the global "irq_type", so ioctl(PCITEST_GET_IRQTYPE) returns the previous
> type. As a result, the wrong type will be displayed in "pcitest".

The global "irq_type" seems a little suspect.  Is it possible to run
multiple tests concurrently?  If so, is this usage safe from races?

> This patch fixes these two issues.
> 
> Fixes: b2ba9225e031 ("misc: pci_endpoint_test: Avoid using module parameter to determine irqtype")
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
> ---
>  drivers/misc/pci_endpoint_test.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c
> index e73b3078cdb6..854480921470 100644
> --- a/drivers/misc/pci_endpoint_test.c
> +++ b/drivers/misc/pci_endpoint_test.c
> @@ -235,7 +235,7 @@ static bool pci_endpoint_test_request_irq(struct pci_endpoint_test *test)
>  	return true;
>  
>  fail:
> -	switch (irq_type) {
> +	switch (test->irq_type) {
>  	case IRQ_TYPE_INTX:
>  		dev_err(dev, "Failed to request IRQ %d for Legacy\n",
>  			pci_irq_vector(pdev, i));
> @@ -739,6 +739,7 @@ static bool pci_endpoint_test_set_irq(struct pci_endpoint_test *test,
>  	if (!pci_endpoint_test_request_irq(test))
>  		goto err;
>  
> +	irq_type = test->irq_type;
>  	return true;
>  
>  err:
> -- 
> 2.25.1
>