linux-kernel - [PATCH] pci: introduce static_nr to indicate domain

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Date:   Sat, 12 Aug 2023 20:21:28 +0800
From:   "Peng Fan (OSS)" <peng.fan@....nxp.com>
To:     bhelgaas@...gle.com, pali@...nel.org
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Peng Fan <peng.fan@....com>
Subject: [PATCH] pci: introduce static_nr to indicate domain_nr from which IDA

From: Peng Fan <peng.fan@....com>

When pci node is created used an overlay, when the overlay is
reverted/destroyed, the "linux,pci-domain" property is no longer
existed, so of_get_pci_domain_nr will return failure. Then
of_pci_bus_release_domain_nr will actually use the dynamic IDA,
even if the IDA was allocated in static IDA.

Introduce a static_nr field in pci_bus to indicate the IDA
is in dynamic or static IDA to address the upper issue.

Fixes: c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()")
Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/pci/pci.c   | 22 ++++++++++++++--------
 include/linux/pci.h |  1 +
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 60230da957e0..5c98502bcda6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6881,10 +6881,10 @@ static void of_pci_reserve_static_domain_nr(void)
 	}
 }
 
-static int of_pci_bus_find_domain_nr(struct device *parent)
+static int of_pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
 {
 	static bool static_domains_reserved = false;
-	int domain_nr;
+	int domain_nr, ret;
 
 	/* On the first call scan device tree for static allocations. */
 	if (!static_domains_reserved) {
@@ -6892,6 +6892,8 @@ static int of_pci_bus_find_domain_nr(struct device *parent)
 		static_domains_reserved = true;
 	}
 
+	bus->static_nr = 0;
+
 	if (parent) {
 		/*
 		 * If domain is in DT, allocate it in static IDA.  This
@@ -6899,10 +6901,14 @@ static int of_pci_bus_find_domain_nr(struct device *parent)
 		 * in DT.
 		 */
 		domain_nr = of_get_pci_domain_nr(parent->of_node);
-		if (domain_nr >= 0)
-			return ida_alloc_range(&pci_domain_nr_static_ida,
-					       domain_nr, domain_nr,
-					       GFP_KERNEL);
+		if (domain_nr >= 0) {
+			ret = ida_alloc_range(&pci_domain_nr_static_ida,
+					      domain_nr, domain_nr, GFP_KERNEL);
+			if (ret >= 0)
+				bus->static_nr = 1;
+
+			return ret;
+		}
 	}
 
 	/*
@@ -6920,7 +6926,7 @@ static void of_pci_bus_release_domain_nr(struct pci_bus *bus, struct device *par
 		return;
 
 	/* Release domain from IDA where it was allocated. */
-	if (of_get_pci_domain_nr(parent->of_node) == bus->domain_nr)
+	if (bus->static_nr)
 		ida_free(&pci_domain_nr_static_ida, bus->domain_nr);
 	else
 		ida_free(&pci_domain_nr_dynamic_ida, bus->domain_nr);
@@ -6928,7 +6934,7 @@ static void of_pci_bus_release_domain_nr(struct pci_bus *bus, struct device *par
 
 int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent)
 {
-	return acpi_disabled ? of_pci_bus_find_domain_nr(parent) :
+	return acpi_disabled ? of_pci_bus_find_domain_nr(bus, parent) :
 			       acpi_pci_bus_find_domain_nr(bus);
 }
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index eeb2e6f6130f..6dd16e069ab8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -665,6 +665,7 @@ struct pci_bus {
 	unsigned char	cur_bus_speed;	/* enum pci_bus_speed */
 #ifdef CONFIG_PCI_DOMAINS_GENERIC
 	int		domain_nr;
+	unsigned int	static_nr:1;
 #endif
 
 	char		name[48];
-- 
2.37.1