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On Thursday 14 July 2022 20:41:30 Pali Rohár wrote: > Replace assignment of PCI domain from atomic_inc_return() to ida_alloc(). > > Use two IDAs, one for static domain allocations (those which are defined in > device tree) and second for dynamic allocations (all other). > > During removal of root bus / host bridge release also allocated domain id. > So released id can be reused again, for example in situation when > dynamically loading and unloading native PCI host bridge drivers. > > This change also allows to mix static device tree assignment and dynamic by > kernel as all static allocations are reserved in dynamic pool. > > Signed-off-by: Pali Rohár <pali@xxxxxxxxxx> > --- > Idea of this patch comes from the following discussion: > https://lore.kernel.org/linux-pci/20210412123936.25555-1-pali@xxxxxxxxxx/t/#u > > Changes in v2: > * Fix broken compilation > --- > drivers/pci/pci.c | 103 +++++++++++++++++++++++++------------------ > drivers/pci/probe.c | 5 +++ > drivers/pci/remove.c | 6 +++ > include/linux/pci.h | 1 + > 4 files changed, 72 insertions(+), 43 deletions(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index cfaf40a540a8..34fdcee6634a 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -6762,60 +6762,70 @@ static void pci_no_domains(void) > } > > #ifdef CONFIG_PCI_DOMAINS_GENERIC > -static atomic_t __domain_nr = ATOMIC_INIT(-1); > +static DEFINE_IDA(pci_domain_nr_static_ida); > +static DEFINE_IDA(pci_domain_nr_dynamic_ida); > > -static int pci_get_new_domain_nr(void) > +static void of_pci_reserve_static_domain_nr(void) > { > - return atomic_inc_return(&__domain_nr); > + struct device_node *np; > + int domain_nr; > + > + for_each_node_by_type(np, "pci") { > + domain_nr = of_get_pci_domain_nr(np); > + if (domain_nr < 0) > + continue; > + /* > + * Permanently allocate domain_nr in dynamic_ida > + * to prevent it from dynamic allocation. > + */ > + ida_alloc_range(&pci_domain_nr_dynamic_ida, > + domain_nr, domain_nr, GFP_KERNEL); > + } > } > > static int of_pci_bus_find_domain_nr(struct device *parent) > { > - static int use_dt_domains = -1; > - int domain = -1; > + static bool static_domains_reserved = false; > + int domain_nr; > > - if (parent) > - domain = of_get_pci_domain_nr(parent->of_node); > + /* On the first call scan device tree for static allocations. */ > + if (!static_domains_reserved) { > + of_pci_reserve_static_domain_nr(); > + static_domains_reserved = true; > + } > + > + if (parent) { > + /* > + * If domain is in DT then allocate it in static IDA. > + * This prevent duplicate static allocations in case > + * of errors 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); > + } > > /* > - * Check DT domain and use_dt_domains values. > - * > - * If DT domain property is valid (domain >= 0) and > - * use_dt_domains != 0, the DT assignment is valid since this means > - * we have not previously allocated a domain number by using > - * pci_get_new_domain_nr(); we should also update use_dt_domains to > - * 1, to indicate that we have just assigned a domain number from > - * DT. > - * > - * If DT domain property value is not valid (ie domain < 0), and we > - * have not previously assigned a domain number from DT > - * (use_dt_domains != 1) we should assign a domain number by > - * using the: > - * > - * pci_get_new_domain_nr() > - * > - * API and update the use_dt_domains value to keep track of method we > - * are using to assign domain numbers (use_dt_domains = 0). > - * > - * All other combinations imply we have a platform that is trying > - * to mix domain numbers obtained from DT and pci_get_new_domain_nr(), > - * which is a recipe for domain mishandling and it is prevented by > - * invalidating the domain value (domain = -1) and printing a > - * corresponding error. > + * If domain was not specified in DT then choose free id from dynamic > + * allocations. All domain numbers from DT are permanently in dynamic > + * allocations to prevent assigning them to other DT nodes without > + * static domain. > */ > - if (domain >= 0 && use_dt_domains) { > - use_dt_domains = 1; > - } else if (domain < 0 && use_dt_domains != 1) { > - use_dt_domains = 0; > - domain = pci_get_new_domain_nr(); > - } else { > - if (parent) > - pr_err("Node %pOF has ", parent->of_node); > - pr_err("Inconsistent \"linux,pci-domain\" property in DT\n"); > - domain = -1; > - } > + return ida_alloc(&pci_domain_nr_dynamic_ida, GFP_KERNEL); > +} > > - return domain; > +static void of_pci_bus_release_domain_nr(struct pci_bus *bus, struct device *parent) > +{ > + if (bus->domain_nr < 0) > + return; > + > + /* Release domain from ida in which was it allocated. */ > + if (of_get_pci_domain_nr(parent->of_node) == bus->domain_nr) > + ida_free(&pci_domain_nr_static_ida, bus->domain_nr); > + else > + ida_free(&pci_domain_nr_dynamic_ida, bus->domain_nr); > } > > int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent) > @@ -6823,6 +6833,13 @@ int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent) > return acpi_disabled ? of_pci_bus_find_domain_nr(parent) : > acpi_pci_bus_find_domain_nr(bus); > } > + > +void pci_bus_release_domain_nr(struct pci_bus *bus, struct device *parent) > +{ > + if (!acpi_disabled) > + return; > + of_pci_bus_release_domain_nr(bus, parent); > +} > #endif > > /** > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c > index 17a969942d37..12092d238403 100644 > --- a/drivers/pci/probe.c > +++ b/drivers/pci/probe.c > @@ -906,6 +906,8 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) > bus->domain_nr = pci_bus_find_domain_nr(bus, parent); > else > bus->domain_nr = bridge->domain_nr; > + if (bus->domain_nr < 0) > + goto free; > #endif > > b = pci_find_bus(pci_domain_nr(bus), bridge->busnr); > @@ -1030,6 +1032,9 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge) > device_del(&bridge->dev); > > free: > +#ifdef CONFIG_PCI_DOMAINS_GENERIC > + pci_bus_release_domain_nr(bus, parent); > +#endif > kfree(bus); > return err; > } > diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c > index 4c54c75050dc..0145aef1b930 100644 > --- a/drivers/pci/remove.c > +++ b/drivers/pci/remove.c > @@ -160,6 +160,12 @@ void pci_remove_root_bus(struct pci_bus *bus) > pci_remove_bus(bus); > host_bridge->bus = NULL; > > +#ifdef CONFIG_PCI_DOMAINS_GENERIC > + /* Release domain_nr if it was dynamically allocated */ > + if (host_bridge->domain_nr == PCI_DOMAIN_NR_NOT_SET) > + pci_bus_release_domain_nr(bus, host_bridge->dev.parent); > +#endif > + > /* remove the host bridge */ > device_del(&host_bridge->dev); > } > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 81a57b498f22..6c7f27e62bcc 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1723,6 +1723,7 @@ static inline int acpi_pci_bus_find_domain_nr(struct pci_bus *bus) > { return 0; } > #endif > int pci_bus_find_domain_nr(struct pci_bus *bus, struct device *parent); > +void pci_bus_release_domain_nr(struct pci_bus *bus, struct device *parent); > #endif > > /* Some architectures require additional setup to direct VGA traffic */ > -- > 2.20.1 >
