In subject, run "git log --oneline drivers/pci/pci.c" and match the
capitalization style.
On Tue, Aug 15, 2023 at 09:37:44AM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@xxxxxxx>
>
> When PCI node was created using an overlay and the overlay is
> reverted/destroyed, the "linux,pci-domain" property no longer
> exists, 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.
Is there any user-visible effect of this issue? For example, is there
any hint in the dmesg log? If so, we should include that hint here.
> Introduce a static_nr field in pci_bus to indicate whether the
> IDA is a dynamic or static in order to free the correct one.
>
> Fixes: c14f7ccc9f5d ("PCI: Assign PCI domain IDs by ida_alloc()")
> Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> ---
>
> V2:
> Update commit message
> Move static_nr:1 to stay besides others :1 fields.
>
> 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;
There are a couple things that make this a little messy:
1) The "static_nr" name isn't great because the struct pci_bus
declaration doesn't have any clue about what it's for. "nr" doesn't
suggest "PCI domain".
2) More importantly, the "static_nr = 1" assignment here doesn't fit
with the design where pci_bus_find_domain_nr() allocates the domain
number and pci_register_host_bridge() stores it in the struct
pci_bus. The bus->domain_nr assignment and the bus->static_nr
assignment really should be in the same place.
I do see the problem that it's hard to return the "static alloc"
info back up the call chain to pci_register_host_bridge() where
bus->domain_nr is assigned, but setting bus->static_nr here in
of_pci_bus_find_domain_nr() seems a little kludgy. I don't have any
good ideas yet, but I'll think about it.
> + 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..222a1729ea7e 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -677,6 +677,7 @@ struct pci_bus {
> struct bin_attribute *legacy_mem; /* Legacy mem */
> unsigned int is_added:1;
> unsigned int unsafe_warn:1; /* warned about RW1C config write */
> + unsigned int static_nr:1;
> };
>
> #define to_pci_bus(n) container_of(n, struct pci_bus, dev)
> --
> 2.37.1
>
