/* * Copyright (C) 2015 Robert Jarzmik * * Scatterlist splitting helpers. * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #include #include struct sg_splitter { struct scatterlist *in_sg0; int nents; off_t skip_sg0; unsigned int length_last_sg; struct scatterlist *out_sg; }; static int sg_calculate_split(struct scatterlist *in, int nents, int nb_splits, off_t skip, const size_t *sizes, struct sg_splitter *splitters, bool mapped) { int i; unsigned int sglen; size_t size = sizes[0], len; struct sg_splitter *curr = splitters; struct scatterlist *sg; for (i = 0; i < nb_splits; i++) { splitters[i].in_sg0 = NULL; splitters[i].nents = 0; } for_each_sg(in, sg, nents, i) { sglen = mapped ? sg_dma_len(sg) : sg->length; if (skip > sglen) { skip -= sglen; continue; } len = min_t(size_t, size, sglen - skip); if (!curr->in_sg0) { curr->in_sg0 = sg; curr->skip_sg0 = skip; } size -= len; curr->nents++; curr->length_last_sg = len; while (!size && (skip + len < sglen) && (--nb_splits > 0)) { curr++; size = *(++sizes); skip += len; len = min_t(size_t, size, sglen - skip); curr->in_sg0 = sg; curr->skip_sg0 = skip; curr->nents = 1; curr->length_last_sg = len; size -= len; } skip = 0; if (!size && --nb_splits > 0) { curr++; size = *(++sizes); } if (!nb_splits) break; } return (size || !splitters[0].in_sg0) ? -EINVAL : 0; } static void sg_split_phys(struct sg_splitter *splitters, const int nb_splits) { int i, j; struct scatterlist *in_sg, *out_sg; struct sg_splitter *split; for (i = 0, split = splitters; i < nb_splits; i++, split++) { in_sg = split->in_sg0; out_sg = split->out_sg; for (j = 0; j < split->nents; j++, out_sg++) { *out_sg = *in_sg; if (!j) { out_sg->offset += split->skip_sg0; out_sg->length -= split->skip_sg0; } else { out_sg->offset = 0; } sg_dma_address(out_sg) = 0; sg_dma_len(out_sg) = 0; in_sg = sg_next(in_sg); } out_sg[-1].length = split->length_last_sg; sg_mark_end(out_sg - 1); } } static void sg_split_mapped(struct sg_splitter *splitters, const int nb_splits) { int i, j; struct scatterlist *in_sg, *out_sg; struct sg_splitter *split; for (i = 0, split = splitters; i < nb_splits; i++, split++) { in_sg = split->in_sg0; out_sg = split->out_sg; for (j = 0; j < split->nents; j++, out_sg++) { sg_dma_address(out_sg) = sg_dma_address(in_sg); sg_dma_len(out_sg) = sg_dma_len(in_sg); if (!j) { sg_dma_address(out_sg) += split->skip_sg0; sg_dma_len(out_sg) -= split->skip_sg0; } in_sg = sg_next(in_sg); } sg_dma_len(--out_sg) = split->length_last_sg; } } /** * sg_split - split a scatterlist into several scatterlists * @in: the input sg list * @in_mapped_nents: the result of a dma_map_sg(in, ...), or 0 if not mapped. * @skip: the number of bytes to skip in the input sg list * @nb_splits: the number of desired sg outputs * @split_sizes: the respective size of each output sg list in bytes * @out: an array where to store the allocated output sg lists * @out_mapped_nents: the resulting sg lists mapped number of sg entries. Might * be NULL if sglist not already mapped (in_mapped_nents = 0) * @gfp_mask: the allocation flag * * This function splits the input sg list into nb_splits sg lists, which are * allocated and stored into out. * The @in is split into : * - @out[0], which covers bytes [@skip .. @skip + @split_sizes[0] - 1] of @in * - @out[1], which covers bytes [@skip + split_sizes[0] .. * @skip + @split_sizes[0] + @split_sizes[1] -1] * etc ... * It will be the caller's duty to kfree() out array members. * * Returns 0 upon success, or error code */ int sg_split(struct scatterlist *in, const int in_mapped_nents, const off_t skip, const int nb_splits, const size_t *split_sizes, struct scatterlist **out, int *out_mapped_nents, gfp_t gfp_mask) { int i, ret; struct sg_splitter *splitters; splitters = kcalloc(nb_splits, sizeof(*splitters), gfp_mask); if (!splitters) return -ENOMEM; ret = sg_calculate_split(in, sg_nents(in), nb_splits, skip, split_sizes, splitters, false); if (ret < 0) goto err; ret = -ENOMEM; for (i = 0; i < nb_splits; i++) { splitters[i].out_sg = kmalloc_array(splitters[i].nents, sizeof(struct scatterlist), gfp_mask); if (!splitters[i].out_sg) goto err; } /* * The order of these 3 calls is important and should be kept. */ sg_split_phys(splitters, nb_splits); ret = sg_calculate_split(in, in_mapped_nents, nb_splits, skip, split_sizes, splitters, true); if (ret < 0) goto err; sg_split_mapped(splitters, nb_splits); for (i = 0; i < nb_splits; i++) { out[i] = splitters[i].out_sg; if (out_mapped_nents) out_mapped_nents[i] = splitters[i].nents; } kfree(splitters); return 0; err: for (i = 0; i < nb_splits; i++) kfree(splitters[i].out_sg); kfree(splitters); return ret; } EXPORT_SYMBOL(sg_split); /th>39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch) tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /drivers/usb/gadget/udc/fotg210-udc.c 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 'drivers/usb/gadget/udc/fotg210-udc.c')