On 2012-9-12 6:00, Bjorn Helgaas wrote: > On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@xxxxxxxxx> wrote: >> There's a typical usage pattern to search a PCI device under a specific >> PCI bus (domian, busno) as below: >> struct pci_bus *pci_bus = pci_find_bus(domain, busno); >> struct pci_dev *pci_dev = pci_get_slot(pci_bus, devfn); >> >> The above code has a race window between pci_find_bus() and pci_get_slot() >> if PCI hotplug operations happen between them which removes the pci_bus. >> So use PCI hotplug safe interface pci_get_domain_bus_and_slot() instead, >> which also reduces code complexity. > > This makes sense to me. If we support hotplug, it's fundamentally > unsafe to keep a struct pci_bus * without having a reference or some > way to make sure it doesn't go away. I think we should try to > eradicate all uses of pci_find_bus() and pci_find_next_bus(). Hi Bjorn I have split out these into a separate patch set at http://www.spinics.net/lists/linux-pci/msg17227.html. In my latest PCI bus lock patch set, I have introduced a new interface pci_get_bus() to replace pci_find_bus(). But pci_find_next_bus() is a little harder to deal with, still need more work here. Thanks! > >> Signed-off-by: Jiang Liu <liuj97@xxxxxxxxx> >> --- >> arch/ia64/sn/kernel/io_common.c | 4 +--- >> drivers/gpu/vga/vgaarb.c | 15 +++------------ >> drivers/pci/hotplug/cpcihp_generic.c | 8 ++------ >> drivers/pci/iov.c | 8 ++------ >> drivers/pci/xen-pcifront.c | 10 ++-------- >> 5 files changed, 10 insertions(+), 35 deletions(-) >> >> diff --git a/arch/ia64/sn/kernel/io_common.c b/arch/ia64/sn/kernel/io_common.c >> index fbb5f2f..8630875 100644 >> --- a/arch/ia64/sn/kernel/io_common.c >> +++ b/arch/ia64/sn/kernel/io_common.c >> @@ -229,7 +229,6 @@ void sn_pci_fixup_slot(struct pci_dev *dev, struct pcidev_info *pcidev_info, >> { >> int segment = pci_domain_nr(dev->bus); >> struct pcibus_bussoft *bs; >> - struct pci_bus *host_pci_bus; >> struct pci_dev *host_pci_dev; >> unsigned int bus_no, devfn; >> >> @@ -245,8 +244,7 @@ void sn_pci_fixup_slot(struct pci_dev *dev, struct pcidev_info *pcidev_info, >> >> bus_no = (pcidev_info->pdi_slot_host_handle >> 32) & 0xff; >> devfn = pcidev_info->pdi_slot_host_handle & 0xffffffff; >> - host_pci_bus = pci_find_bus(segment, bus_no); >> - host_pci_dev = pci_get_slot(host_pci_bus, devfn); >> + host_pci_dev = pci_get_domain_bus_and_slot(segment, bus_no, devfn); >> >> pcidev_info->host_pci_dev = host_pci_dev; >> pcidev_info->pdi_linux_pcidev = dev; >> diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c >> index 3df8fc0..b6852b7 100644 >> --- a/drivers/gpu/vga/vgaarb.c >> +++ b/drivers/gpu/vga/vgaarb.c >> @@ -1066,7 +1066,6 @@ static ssize_t vga_arb_write(struct file *file, const char __user * buf, >> } >> >> } else if (strncmp(curr_pos, "target ", 7) == 0) { >> - struct pci_bus *pbus; >> unsigned int domain, bus, devfn; >> struct vga_device *vgadev; >> >> @@ -1085,19 +1084,11 @@ static ssize_t vga_arb_write(struct file *file, const char __user * buf, >> pr_debug("vgaarb: %s ==> %x:%x:%x.%x\n", curr_pos, >> domain, bus, PCI_SLOT(devfn), PCI_FUNC(devfn)); >> >> - pbus = pci_find_bus(domain, bus); >> - pr_debug("vgaarb: pbus %p\n", pbus); >> - if (pbus == NULL) { >> - pr_err("vgaarb: invalid PCI domain and/or bus address %x:%x\n", >> - domain, bus); >> - ret_val = -ENODEV; >> - goto done; >> - } >> - pdev = pci_get_slot(pbus, devfn); >> + pdev = pci_get_domain_bus_and_slot(domain, bus, devfn); >> pr_debug("vgaarb: pdev %p\n", pdev); >> if (!pdev) { >> - pr_err("vgaarb: invalid PCI address %x:%x\n", >> - bus, devfn); >> + pr_err("vgaarb: invalid PCI address %x:%x:%x\n", >> + domain, bus, devfn); >> ret_val = -ENODEV; >> goto done; >> } >> diff --git a/drivers/pci/hotplug/cpcihp_generic.c b/drivers/pci/hotplug/cpcihp_generic.c >> index 81af764..a6a71c4 100644 >> --- a/drivers/pci/hotplug/cpcihp_generic.c >> +++ b/drivers/pci/hotplug/cpcihp_generic.c >> @@ -154,12 +154,8 @@ static int __init cpcihp_generic_init(void) >> if(!r) >> return -EBUSY; >> >> - bus = pci_find_bus(0, bridge_busnr); >> - if (!bus) { >> - err("Invalid bus number %d", bridge_busnr); >> - return -EINVAL; >> - } >> - dev = pci_get_slot(bus, PCI_DEVFN(bridge_slot, 0)); >> + dev = pci_get_domain_bus_and_slot(0, bridge_busnr, >> + PCI_DEVFN(bridge_slot, 0)); >> if(!dev || dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) { >> err("Invalid bridge device %s", bridge); >> pci_dev_put(dev); >> diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c >> index 74bbaf8..c7d2969 100644 >> --- a/drivers/pci/iov.c >> +++ b/drivers/pci/iov.c >> @@ -152,15 +152,11 @@ failed1: >> static void virtfn_remove(struct pci_dev *dev, int id, int reset) >> { >> char buf[VIRTFN_ID_LEN]; >> - struct pci_bus *bus; >> struct pci_dev *virtfn; >> struct pci_sriov *iov = dev->sriov; >> >> - bus = pci_find_bus(pci_domain_nr(dev->bus), virtfn_bus(dev, id)); >> - if (!bus) >> - return; >> - >> - virtfn = pci_get_slot(bus, virtfn_devfn(dev, id)); >> + virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus), >> + virtfn_bus(dev, id), virtfn_devfn(dev, id)); >> if (!virtfn) >> return; >> >> diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c >> index d6cc62c..def8d0b 100644 >> --- a/drivers/pci/xen-pcifront.c >> +++ b/drivers/pci/xen-pcifront.c >> @@ -982,7 +982,6 @@ static int pcifront_detach_devices(struct pcifront_device *pdev) >> int err = 0; >> int i, num_devs; >> unsigned int domain, bus, slot, func; >> - struct pci_bus *pci_bus; >> struct pci_dev *pci_dev; >> char str[64]; >> >> @@ -1032,13 +1031,8 @@ static int pcifront_detach_devices(struct pcifront_device *pdev) >> goto out; >> } >> >> - pci_bus = pci_find_bus(domain, bus); >> - if (!pci_bus) { >> - dev_dbg(&pdev->xdev->dev, "Cannot get bus %04x:%02x\n", >> - domain, bus); >> - continue; >> - } >> - pci_dev = pci_get_slot(pci_bus, PCI_DEVFN(slot, func)); >> + pci_dev = pci_get_domain_bus_and_slot(domain, bus, >> + PCI_DEVFN(slot, func)); >> if (!pci_dev) { >> dev_dbg(&pdev->xdev->dev, >> "Cannot get PCI device %04x:%02x:%02x.%d\n", >> -- >> 1.7.9.5 >> > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
