| Message ID | 1344355862-2726-2-git-send-email-jiang.liu@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@gmail.com> 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(). > Signed-off-by: Jiang Liu <liuj97@gmail.com> > --- > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 2012-9-12 6:00, Bjorn Helgaas wrote: > On Tue, Aug 7, 2012 at 10:10 AM, Jiang Liu <liuj97@gmail.com> 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@gmail.com> >> --- >> 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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",
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. Signed-off-by: Jiang Liu <liuj97@gmail.com> --- 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(-)