linux-kernel - [PATCH v2] usb: Check !irq instead of irq == NO

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Message-Id: <13feefdf6b240817944e6441e26a8ddc1d81ced1.1668102802.git.christophe.leroy@csgroup.eu>
Date:   Thu, 10 Nov 2022 18:54:35 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org
Subject: [PATCH v2] usb: Check !irq instead of irq == NO_IRQ

NO_IRQ is a relic from the old days. It is not used anymore in core
functions. By the way, function irq_of_parse_and_map() returns value 0
on error.

In some drivers, NO_IRQ is erroneously used to check the return of
irq_of_parse_and_map().

It is not a real bug today because the only architectures using the
drivers being fixed by this patch define NO_IRQ as 0, but there are
architectures which define NO_IRQ as -1. If one day those
architectures start using the non fixed drivers, there will be a
problem.

Long time ago Linus advocated for not using NO_IRQ, see
https://lkml.org/lkml/2005/11/21/221 . He re-iterated the same view
recently in https://lkml.org/lkml/2022/10/12/622

So test !irq instead of tesing irq == NO_IRQ.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 drivers/usb/host/ehci-grlib.c  | 2 +-
 drivers/usb/host/ehci-ppc-of.c | 2 +-
 drivers/usb/host/fhci-hcd.c    | 2 +-
 drivers/usb/host/ohci-ppc-of.c | 2 +-
 drivers/usb/host/uhci-grlib.c  | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/host/ehci-grlib.c b/drivers/usb/host/ehci-grlib.c
index a2c3b4ec8a8b..0717f2ccf49d 100644
--- a/drivers/usb/host/ehci-grlib.c
+++ b/drivers/usb/host/ehci-grlib.c
@@ -99,7 +99,7 @@ static int ehci_hcd_grlib_probe(struct platform_device *op)
 	hcd->rsrc_len = resource_size(&res);
 
 	irq = irq_of_parse_and_map(dn, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		dev_err(&op->dev, "%s: irq_of_parse_and_map failed\n",
 			__FILE__);
 		rv = -EBUSY;
diff --git a/drivers/usb/host/ehci-ppc-of.c b/drivers/usb/host/ehci-ppc-of.c
index 28a19693c19f..62a0a193798c 100644
--- a/drivers/usb/host/ehci-ppc-of.c
+++ b/drivers/usb/host/ehci-ppc-of.c
@@ -119,7 +119,7 @@ static int ehci_hcd_ppc_of_probe(struct platform_device *op)
 	hcd->rsrc_len = resource_size(&res);
 
 	irq = irq_of_parse_and_map(dn, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		dev_err(&op->dev, "%s: irq_of_parse_and_map failed\n",
 			__FILE__);
 		rv = -EBUSY;
diff --git a/drivers/usb/host/fhci-hcd.c b/drivers/usb/host/fhci-hcd.c
index 95a44462bed0..64a64140c2fd 100644
--- a/drivers/usb/host/fhci-hcd.c
+++ b/drivers/usb/host/fhci-hcd.c
@@ -676,7 +676,7 @@ static int of_fhci_probe(struct platform_device *ofdev)
 
 	/* USB Host interrupt. */
 	usb_irq = irq_of_parse_and_map(node, 0);
-	if (usb_irq == NO_IRQ) {
+	if (!usb_irq) {
 		dev_err(dev, "could not get usb irq\n");
 		ret = -EINVAL;
 		goto err_usb_irq;
diff --git a/drivers/usb/host/ohci-ppc-of.c b/drivers/usb/host/ohci-ppc-of.c
index 591f675cc930..f2f6c832ec98 100644
--- a/drivers/usb/host/ohci-ppc-of.c
+++ b/drivers/usb/host/ohci-ppc-of.c
@@ -120,7 +120,7 @@ static int ohci_hcd_ppc_of_probe(struct platform_device *op)
 	}
 
 	irq = irq_of_parse_and_map(dn, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		dev_err(&op->dev, "%s: irq_of_parse_and_map failed\n",
 			__FILE__);
 		rv = -EBUSY;
diff --git a/drivers/usb/host/uhci-grlib.c b/drivers/usb/host/uhci-grlib.c
index 3ef6d52839e5..907d5f01edfd 100644
--- a/drivers/usb/host/uhci-grlib.c
+++ b/drivers/usb/host/uhci-grlib.c
@@ -116,7 +116,7 @@ static int uhci_hcd_grlib_probe(struct platform_device *op)
 	hcd->rsrc_len = resource_size(&res);
 
 	irq = irq_of_parse_and_map(dn, 0);
-	if (irq == NO_IRQ) {
+	if (!irq) {
 		printk(KERN_ERR "%s: irq_of_parse_and_map failed\n", __FILE__);
 		rv = -EBUSY;
 		goto err_usb;
-- 
2.37.1