From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Jiang Liu To: Bjorn Helgaas , Don Dutile , Yinghai Lu , Greg KH , Kenji Kaneshige Cc: Jiang Liu , Taku Izumi , "Rafael J . Wysocki" , Yijing Wang , Xinwei Hu , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Jiang Liu Subject: [RFC PATCH v1 08/22] PCI: introduce hotplug safe search interfaces for PCI bus/device Date: Wed, 8 Aug 2012 00:10:48 +0800 Message-Id: <1344355862-2726-9-git-send-email-jiang.liu@huawei.com> In-Reply-To: <1344355862-2726-1-git-send-email-jiang.liu@huawei.com> References: <1344355862-2726-1-git-send-email-jiang.liu@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Function pci_find_bus() is not hotplug safe because it doesn't hold any reference on the returned bus, so the bus may be destroyed by hotplug operations just after returning from pci_find_bus. This patch introduces a hotplug safe interface to get and lock a specific PCI bus. It also provides several help interfaces to reduce code complexity. Signed-off-by: Jiang Liu --- drivers/pci/bus.c | 34 ++++++++++++++++++++++++++++++++++ drivers/pci/search.c | 44 ++++++++++++++++++++++++++++++++++---------- include/linux/pci.h | 10 ++++++++++ 3 files changed, 78 insertions(+), 10 deletions(-) diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c index aa25fcf..b6aacaa 100644 --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -426,6 +426,40 @@ void pci_bus_change_state(struct pci_bus *bus, int old, int new, bool unlock) } EXPORT_SYMBOL(pci_bus_change_state); +struct pci_bus *__pci_get_and_lock_bus(int domain, int busnr, int states) +{ + struct pci_bus *bus; + + bus = pci_get_bus(domain, busnr); + if (bus && pci_bus_lock_states(bus, states) < 0) { + pci_bus_put(bus); + bus = NULL; + } + + return bus; +} +EXPORT_SYMBOL(__pci_get_and_lock_bus); + +struct pci_bus *pci_lock_subordinate(struct pci_dev *dev, int states) +{ + struct pci_bus *bus = dev->subordinate; + + if (bus && pci_bus_lock_states(bus, states) > 0) + return bus; + + return NULL; +} +EXPORT_SYMBOL(pci_lock_subordinate); + +void pci_unlock_and_put_bus(struct pci_bus *bus) +{ + if (bus) { + pci_bus_unlock(bus); + pci_bus_put(bus); + } +} +EXPORT_SYMBOL(pci_unlock_and_put_bus); + EXPORT_SYMBOL(pci_bus_alloc_resource); EXPORT_SYMBOL_GPL(pci_bus_add_device); EXPORT_SYMBOL(pci_bus_add_devices); diff --git a/drivers/pci/search.c b/drivers/pci/search.c index f1147a7..c0a8a2b 100644 --- a/drivers/pci/search.c +++ b/drivers/pci/search.c @@ -69,6 +69,35 @@ static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr) } /** + * pci_get_bus - get PCI bus from a given domain and bus number + * @domain: number of PCI domain to search + * @busnr: number of desired PCI bus + * + * Given a PCI bus number and domain number, the desired PCI bus is located + * in the global list of PCI buses. If the bus is found, a reference count + * is held on the returned PCI bus. If no bus is found, %NULL is returned. + */ +struct pci_bus *pci_get_bus(int domain, int busnr) +{ + struct pci_bus *bus; + struct pci_bus *tmp_bus = NULL; + + down_read(&pci_bus_sem); + list_for_each_entry(bus, &pci_root_buses, node) + if (pci_domain_nr(bus) == domain) { + tmp_bus = pci_do_find_bus(bus, busnr); + if (tmp_bus) { + pci_bus_get(tmp_bus); + break; + } + } + up_read(&pci_bus_sem); + + return tmp_bus; +} +EXPORT_SYMBOL(pci_get_bus); + +/** * pci_find_bus - locate PCI bus from a given domain and bus number * @domain: number of PCI domain to search * @busnr: number of desired PCI bus @@ -79,17 +108,12 @@ static struct pci_bus *pci_do_find_bus(struct pci_bus *bus, unsigned char busnr) */ struct pci_bus * pci_find_bus(int domain, int busnr) { - struct pci_bus *bus = NULL; - struct pci_bus *tmp_bus; + struct pci_bus *bus; - while ((bus = pci_find_next_bus(bus)) != NULL) { - if (pci_domain_nr(bus) != domain) - continue; - tmp_bus = pci_do_find_bus(bus, busnr); - if (tmp_bus) - return tmp_bus; - } - return NULL; + bus = pci_get_bus(domain, busnr); + pci_bus_put(bus); + + return bus; } /** diff --git a/include/linux/pci.h b/include/linux/pci.h index e2ef517..9e52e88 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -488,6 +488,15 @@ extern int pci_bus_lock_states(struct pci_bus *bus, int states); extern void pci_bus_unlock(struct pci_bus *bus); extern void pci_bus_change_state(struct pci_bus *bus, int new, int old, bool unlock); +extern struct pci_bus *pci_lock_subordinate(struct pci_dev *dev, int states); +extern struct pci_bus *__pci_get_and_lock_bus(int domain, int busnr, + int states); +extern void pci_unlock_and_put_bus(struct pci_bus *bus); + +static inline struct pci_bus *pci_get_and_lock_bus(int domain, int busnr) +{ + return __pci_get_and_lock_bus(domain, busnr, PCI_BUS_STATE_WORKING); +} #define pci_bus_b(n) list_entry(n, struct pci_bus, node) #define to_pci_bus(n) container_of(n, struct pci_bus, dev) @@ -734,6 +743,7 @@ void pcibios_bus_to_resource(struct pci_dev *dev, struct resource *res, struct pci_bus_region *region); void pcibios_scan_specific_bus(int busn); extern struct pci_bus *pci_find_bus(int domain, int busnr); +struct pci_bus *pci_get_bus(int domain, int busnr); void pci_bus_add_devices(const struct pci_bus *bus); struct pci_bus *pci_scan_bus_parented(struct device *parent, int bus, struct pci_ops *ops, void *sysdata); -- 1.7.9.5