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Message-ID: <87ecr5xv9w.wl-maz@kernel.org>
Date: Tue, 14 Oct 2025 18:12:11 +0100
From: Marc Zyngier <maz@...nel.org>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
devicetree@...r.kernel.org, linux-pci@...r.kernel.org, Sascha Bischoff
<sascha.bischoff@....com>, Thomas Gleixner <tglx@...utronix.de>, Rob
Herring <robh@...nel.org>, Frank Li <Frank.Li@....com>, Scott Branden
<sbranden@...adcom.com>, Bjorn Helgaas <bhelgaas@...gle.com>, Ray Jui
<rjui@...adcom.com>, Manivannan Sadhasivam <mani@...nel.org>, Krzysztof
Wilczyński <kwilczynski@...nel.org>
Subject: Re: [PATCH v2 4/4] irqchip/gic-its: Rework platform MSI deviceID detection
On Tue, 14 Oct 2025 10:58:45 +0100,
Lorenzo Pieralisi <lpieralisi@...nel.org> wrote:
>
> Current code retrieving platform devices MSI devID in the GIC ITS MSI
> parent helpers suffers from some minor issues:
>
> - It leaks a struct device_node reference
> - It triggers an excessive WARN_ON on wrong of_phandle_args count detection
Well, if your DT is that rotten, maybe you actually deserve some
console spamming, don't you think?
> - It is duplicated between GICv3 and GICv5 for no good reason
> - It does not use the OF phandle iterator code that simplifies
> the msi-parent property parsing
>
> Implement a helper function that addresses the full set of issues in one go
> by consolidating GIC v3 and v5 code and converting the msi-parent parsing
> loop to the more modern OF phandle iterator API, fixing the
> struct device_node reference leak in the process.
>
> Signed-off-by: Lorenzo Pieralisi <lpieralisi@...nel.org>
> Cc: Sascha Bischoff <sascha.bischoff@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Frank Li <Frank.Li@....com>
> Cc: Marc Zyngier <maz@...nel.org>
> ---
> drivers/irqchip/irq-gic-its-msi-parent.c | 98 ++++++++----------------
> 1 file changed, 33 insertions(+), 65 deletions(-)
>
> diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
> index eb1473f1448a..a65f762b7dd4 100644
> --- a/drivers/irqchip/irq-gic-its-msi-parent.c
> +++ b/drivers/irqchip/irq-gic-its-msi-parent.c
> @@ -142,83 +142,51 @@ static int its_v5_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
> #define its_v5_pci_msi_prepare NULL
> #endif /* !CONFIG_PCI_MSI */
>
> -static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
> - u32 *dev_id)
> +static int __of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev, u32 *dev_id,
> + phys_addr_t *pa, bool is_v5)
> {
> - int ret, index = 0;
> + struct of_phandle_iterator it;
> + uint32_t args;
Use u32, this is not userspace-visible (the OF code will cope). And
move it to where it matters instead of having such a wide scope.
> + int ret;
>
> /* Suck the DeviceID out of the msi-parent property */
> - do {
> - struct of_phandle_args args;
> + of_for_each_phandle(&it, ret, dev->of_node, "msi-parent", "#msi-cells", -1) {
> + /* GICv5 ITS domain matches the MSI controller node parent */
> + struct device_node *np __free(device_node) = is_v5 ? of_get_parent(it.node)
> + : of_node_get(it.node);
>
> - ret = of_parse_phandle_with_args(dev->of_node,
> - "msi-parent", "#msi-cells",
> - index, &args);
> - if (args.np == irq_domain_get_of_node(domain)) {
> - if (WARN_ON(args.args_count != 1))
> - return -EINVAL;
> - *dev_id = args.args[0];
> - break;
> + if (np == irq_domain_get_of_node(domain)) {
> + if (of_phandle_iterator_args(&it, &args, 1) != 1) {
> + dev_warn(dev, "Bogus msi-parent property\n");
> + ret = -EINVAL;
> + }
> +
> + if (!ret && is_v5)
> + ret = its_translate_frame_address(it.node, pa);
Why do you need this is_v5 hack, since the only case were you pass a
pointer to get the translate register address is for v5?
> +
> + if (!ret)
> + *dev_id = args;
> +
> + of_node_put(it.node);
> + return ret;
> }
> - index++;
> - } while (!ret);
> -
> - if (ret) {
> - struct device_node *np = NULL;
> -
> - ret = of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &np, dev_id);
> - if (np)
> - of_node_put(np);
> }
>
> - return ret;
> + struct device_node *msi_ctrl __free(device_node) = NULL;
> +
> + return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
> +}
> +
> +static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
> + u32 *dev_id)
> +{
> + return __of_pmsi_get_dev_id(domain, dev, dev_id, NULL, false);
> }
At this stage, we really don't need these on-liners, as they only
obfuscate the logic. Just use the main helper directly. Something like
the hack below.
M.
diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
index a65f762b7dd4d..7c82fd152655e 100644
--- a/drivers/irqchip/irq-gic-its-msi-parent.c
+++ b/drivers/irqchip/irq-gic-its-msi-parent.c
@@ -142,26 +142,27 @@ static int its_v5_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
#define its_v5_pci_msi_prepare NULL
#endif /* !CONFIG_PCI_MSI */
-static int __of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev, u32 *dev_id,
- phys_addr_t *pa, bool is_v5)
+static int of_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev, u32 *dev_id,
+ phys_addr_t *pa)
{
struct of_phandle_iterator it;
- uint32_t args;
int ret;
/* Suck the DeviceID out of the msi-parent property */
of_for_each_phandle(&it, ret, dev->of_node, "msi-parent", "#msi-cells", -1) {
/* GICv5 ITS domain matches the MSI controller node parent */
- struct device_node *np __free(device_node) = is_v5 ? of_get_parent(it.node)
+ struct device_node *np __free(device_node) = pa ? of_get_parent(it.node)
: of_node_get(it.node);
if (np == irq_domain_get_of_node(domain)) {
+ u32 args;
+
if (of_phandle_iterator_args(&it, &args, 1) != 1) {
dev_warn(dev, "Bogus msi-parent property\n");
ret = -EINVAL;
}
- if (!ret && is_v5)
+ if (!ret && pa)
ret = its_translate_frame_address(it.node, pa);
if (!ret)
@@ -177,18 +178,6 @@ static int __of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev, u
return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
}
-static int of_pmsi_get_dev_id(struct irq_domain *domain, struct device *dev,
- u32 *dev_id)
-{
- return __of_pmsi_get_dev_id(domain, dev, dev_id, NULL, false);
-}
-
-static int of_v5_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev,
- u32 *dev_id, phys_addr_t *pa)
-{
- return __of_pmsi_get_dev_id(domain, dev, dev_id, pa, true);
-}
-
int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
{
return -1;
@@ -202,7 +191,7 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
int ret;
if (dev->of_node)
- ret = of_pmsi_get_dev_id(domain->parent, dev, &dev_id);
+ ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, NULL);
else
ret = iort_pmsi_get_dev_id(dev, &dev_id);
if (ret)
@@ -230,7 +219,7 @@ static int its_v5_pmsi_prepare(struct irq_domain *domain, struct device *dev,
if (!dev->of_node)
return -ENODEV;
- ret = of_v5_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
+ ret = of_pmsi_get_msi_info(domain->parent, dev, &dev_id, &pa);
if (ret)
return ret;
--
Jazz isn't dead. It just smells funny.
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