/* * PCI Backend - Provides restricted access to the real PCI bus topology * to the frontend * * Author: Ryan Wilson */ #include #include #include #include "pciback.h" struct passthrough_dev_data { /* Access to dev_list must be protected by lock */ struct list_head dev_list; struct mutex lock; }; static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev, unsigned int domain, unsigned int bus, unsigned int devfn) { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry; struct pci_dev *dev = NULL; mutex_lock(&dev_data->lock); list_for_each_entry(dev_entry, &dev_data->dev_list, list) { if (domain == (unsigned int)pci_domain_nr(dev_entry->dev->bus) && bus == (unsigned int)dev_entry->dev->bus->number && devfn == dev_entry->dev->devfn) { dev = dev_entry->dev; break; } } mutex_unlock(&dev_data->lock); return dev; } static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev, struct pci_dev *dev, int devid, publish_pci_dev_cb publish_cb) { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry; unsigned int domain, bus, devfn; int err; dev_entry = kmalloc(sizeof(*dev_entry), GFP_KERNEL); if (!dev_entry) return -ENOMEM; dev_entry->dev = dev; mutex_lock(&dev_data->lock); list_add_tail(&dev_entry->list, &dev_data->dev_list); mutex_unlock(&dev_data->lock); /* Publish this device. */ domain = (unsigned int)pci_domain_nr(dev->bus); bus = (unsigned int)dev->bus->number; devfn = dev->devfn; err = publish_cb(pdev, domain, bus, devfn, devid); return err; } static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev, struct pci_dev *dev, bool lock) { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry, *t; struct pci_dev *found_dev = NULL; mutex_lock(&dev_data->lock); list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) { if (dev_entry->dev == dev) { list_del(&dev_entry->list); found_dev = dev_entry->dev; kfree(dev_entry); } } mutex_unlock(&dev_data->lock); if (found_dev) { if (lock) device_lock(&found_dev->dev); pcistub_put_pci_dev(found_dev); if (lock) device_unlock(&found_dev->dev); } } static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev) { struct passthrough_dev_data *dev_data; dev_data = kmalloc(sizeof(*dev_data), GFP_KERNEL); if (!dev_data) return -ENOMEM; mutex_init(&dev_data->lock); INIT_LIST_HEAD(&dev_data->dev_list); pdev->pci_dev_data = dev_data; return 0; } static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev, publish_pci_root_cb publish_root_cb) { int err = 0; struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry, *e; struct pci_dev *dev; int found; unsigned int domain, bus; mutex_lock(&dev_data->lock); list_for_each_entry(dev_entry, &dev_data->dev_list, list) { /* Only publish this device as a root if none of its * parent bridges are exported */ found = 0; dev = dev_entry->dev->bus->self; for (; !found && dev != NULL; dev = dev->bus->self) { list_for_each_entry(e, &dev_data->dev_list, list) { if (dev == e->dev) { found = 1; break; } } } domain = (unsigned int)pci_domain_nr(dev_entry->dev->bus); bus = (unsigned int)dev_entry->dev->bus->number; if (!found) { err = publish_root_cb(pdev, domain, bus); if (err) break; } } mutex_unlock(&dev_data->lock); return err; } static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev) { struct passthrough_dev_data *dev_data = pdev->pci_dev_data; struct pci_dev_entry *dev_entry, *t; list_for_each_entry_safe(dev_entry, t, &dev_data->dev_list, list) { struct pci_dev *dev = dev_entry->dev; list_del(&dev_entry->list); device_lock(&dev->dev); pcistub_put_pci_dev(dev); device_unlock(&dev->dev); kfree(dev_entry); } kfree(dev_data); pdev->pci_dev_data = NULL; } static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev, struct xen_pcibk_device *pdev, unsigned int *domain, unsigned int *bus, unsigned int *devfn) { *domain = pci_domain_nr(pcidev->bus); *bus = pcidev->bus->number; *devfn = pcidev->devfn; return 1; } const struct xen_pcibk_backend xen_pcibk_passthrough_backend = { .name = "passthrough", .init = __xen_pcibk_init_devices, .free = __xen_pcibk_release_devices, .find = __xen_pcibk_get_pcifront_dev, .publish = __xen_pcibk_publish_pci_roots, .release = __xen_pcibk_release_pci_dev, .add = __xen_pcibk_add_pci_dev, .get = __xen_pcibk_get_pci_dev, }; > committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800 commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch) tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /fs/xfs/libxfs/xfs_alloc_btree.h parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/xfs/libxfs/xfs_alloc_btree.h')