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authorDaniel Vetter <daniel.vetter@ffwll.ch>2020-03-24 15:45:40 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2020-03-26 16:49:13 +0300
commitc6603c740e0e3492c9c95fdab833375bf7117b6b (patch)
tree5b17116a390079799c7fde9c34982f813eb7d2c4 /drivers/gpu/drm/drm_managed.c
parent0ce542f7317117a02d65183e047a09911fa08afe (diff)
downloadlinux-c6603c740e0e3492c9c95fdab833375bf7117b6b.tar.xz
drm: add managed resources tied to drm_device
We have lots of these. And the cleanup code tends to be of dubious quality. The biggest wrong pattern is that developers use devm_, which ties the release action to the underlying struct device, whereas all the userspace visible stuff attached to a drm_device can long outlive that one (e.g. after a hotunplug while userspace has open files and mmap'ed buffers). Give people what they want, but with more correctness. Mostly copied from devres.c, with types adjusted to fit drm_device and a few simplifications - I didn't (yet) copy over everything. Since the types don't match code sharing looked like a hopeless endeavour. For now it's only super simplified, no groups, you can't remove actions (but kfree exists, we'll need that soon). Plus all specific to drm_device ofc, including the logging. Which I didn't bother to make compile-time optional, since none of the other drm logging is compile time optional either. One tricky bit here is the chicken&egg between allocating your drm_device structure and initiliazing it with drm_dev_init. For perfect onion unwinding we'd need to have the action to kfree the allocation registered before drm_dev_init registers any of its own release handlers. But drm_dev_init doesn't know where exactly the drm_device is emebedded into the overall structure, and by the time it returns it'll all be too late. And forcing drivers to be able clean up everything except the one kzalloc is silly. Work around this by having a very special final_kfree pointer. This also avoids troubles with the list head possibly disappearing from underneath us when we release all resources attached to the drm_device. v2: Do all the kerneldoc at the end, to avoid lots of fairly pointless shuffling while getting everything into shape. v3: Add static to add/del_dr (Neil) Move typo fix to the right patch (Neil) v4: Enforce contract for drmm_add_final_kfree: Use ksize() to check that the drm_device is indeed contained somewhere in the final kfree(). Because we need that or the entire managed release logic blows up in a pile of use-after-frees. Motivated by a discussion with Laurent. v5: Review from Laurent: - %zu instead of casting size_t - header guards - sorting of includes - guarding of data assignment if we didn't allocate it for a NULL pointer - delete spurious newline - cast void* data parameter correctly in ->release call, no idea how this even worked before v6: Review from Sam - Add the kerneldoc for the managed sub-struct back in, even if it doesn't show up in the generated html somehow. - Explain why __always_inline. - Fix bisectability around the final kfree() in drm_dev_relase(). This is just interim code which will disappear again. - Some whitespace polish. - Add debug output when drmm_add_action or drmm_kmalloc fail. v7: My bisectability fix wasn't up to par as noticed by smatch. v8: Remove unecessary {} around if else v9: Use kstrdup_const, which requires kfree_const and introducing a free_dr() helper (Thomas). v10: kfree_const goes boom on the plain "kmalloc" assignment, somehow we need to wrap that in kstrdup_const() too!! Also renumber revision log, I somehow reset it midway thruh. Reviewed-by: Sam Ravnborg <sam@ravnborg.org> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Neil Armstrong <narmstrong@baylibre.com Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200324124540.3227396-1-daniel.vetter@ffwll.ch
Diffstat (limited to 'drivers/gpu/drm/drm_managed.c')
-rw-r--r--drivers/gpu/drm/drm_managed.c193
1 files changed, 193 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_managed.c b/drivers/gpu/drm/drm_managed.c
new file mode 100644
index 000000000000..46d679b66e4d
--- /dev/null
+++ b/drivers/gpu/drm/drm_managed.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Intel
+ *
+ * Based on drivers/base/devres.c
+ */
+
+#include <drm/drm_managed.h>
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <drm/drm_device.h>
+#include <drm/drm_print.h>
+
+/**
+ * DOC: managed resources
+ *
+ * Inspired by struct &device managed resources, but tied to the lifetime of
+ * struct &drm_device, which can outlive the underlying physical device, usually
+ * when userspace has some open files and other handles to resources still open.
+ */
+struct drmres_node {
+ struct list_head entry;
+ drmres_release_t release;
+ const char *name;
+ size_t size;
+};
+
+struct drmres {
+ struct drmres_node node;
+ /*
+ * Some archs want to perform DMA into kmalloc caches
+ * and need a guaranteed alignment larger than
+ * the alignment of a 64-bit integer.
+ * Thus we use ARCH_KMALLOC_MINALIGN here and get exactly the same
+ * buffer alignment as if it was allocated by plain kmalloc().
+ */
+ u8 __aligned(ARCH_KMALLOC_MINALIGN) data[];
+};
+
+static void free_dr(struct drmres *dr)
+{
+ kfree_const(dr->node.name);
+ kfree(dr);
+}
+
+void drm_managed_release(struct drm_device *dev)
+{
+ struct drmres *dr, *tmp;
+
+ drm_dbg_drmres(dev, "drmres release begin\n");
+ list_for_each_entry_safe(dr, tmp, &dev->managed.resources, node.entry) {
+ drm_dbg_drmres(dev, "REL %p %s (%zu bytes)\n",
+ dr, dr->node.name, dr->node.size);
+
+ if (dr->node.release)
+ dr->node.release(dev, dr->node.size ? *(void **)&dr->data : NULL);
+
+ list_del(&dr->node.entry);
+ free_dr(dr);
+ }
+ drm_dbg_drmres(dev, "drmres release end\n");
+}
+
+/*
+ * Always inline so that kmalloc_track_caller tracks the actual interesting
+ * caller outside of drm_managed.c.
+ */
+static __always_inline struct drmres * alloc_dr(drmres_release_t release,
+ size_t size, gfp_t gfp, int nid)
+{
+ size_t tot_size;
+ struct drmres *dr;
+
+ /* We must catch any near-SIZE_MAX cases that could overflow. */
+ if (unlikely(check_add_overflow(sizeof(*dr), size, &tot_size)))
+ return NULL;
+
+ dr = kmalloc_node_track_caller(tot_size, gfp, nid);
+ if (unlikely(!dr))
+ return NULL;
+
+ memset(dr, 0, offsetof(struct drmres, data));
+
+ INIT_LIST_HEAD(&dr->node.entry);
+ dr->node.release = release;
+ dr->node.size = size;
+
+ return dr;
+}
+
+static void del_dr(struct drm_device *dev, struct drmres *dr)
+{
+ list_del_init(&dr->node.entry);
+
+ drm_dbg_drmres(dev, "DEL %p %s (%lu bytes)\n",
+ dr, dr->node.name, (unsigned long) dr->node.size);
+}
+
+static void add_dr(struct drm_device *dev, struct drmres *dr)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->managed.lock, flags);
+ list_add(&dr->node.entry, &dev->managed.resources);
+ spin_unlock_irqrestore(&dev->managed.lock, flags);
+
+ drm_dbg_drmres(dev, "ADD %p %s (%lu bytes)\n",
+ dr, dr->node.name, (unsigned long) dr->node.size);
+}
+
+void drmm_add_final_kfree(struct drm_device *dev, void *container)
+{
+ WARN_ON(dev->managed.final_kfree);
+ WARN_ON(dev < (struct drm_device *) container);
+ WARN_ON(dev + 1 >=
+ (struct drm_device *) (container + ksize(container)));
+ dev->managed.final_kfree = container;
+}
+EXPORT_SYMBOL(drmm_add_final_kfree);
+
+int __drmm_add_action(struct drm_device *dev,
+ drmres_release_t action,
+ void *data, const char *name)
+{
+ struct drmres *dr;
+ void **void_ptr;
+
+ dr = alloc_dr(action, data ? sizeof(void*) : 0,
+ GFP_KERNEL | __GFP_ZERO,
+ dev_to_node(dev->dev));
+ if (!dr) {
+ drm_dbg_drmres(dev, "failed to add action %s for %p\n",
+ name, data);
+ return -ENOMEM;
+ }
+
+ dr->node.name = kstrdup_const(name, GFP_KERNEL);
+ if (data) {
+ void_ptr = (void **)&dr->data;
+ *void_ptr = data;
+ }
+
+ add_dr(dev, dr);
+
+ return 0;
+}
+EXPORT_SYMBOL(__drmm_add_action);
+
+void *drmm_kmalloc(struct drm_device *dev, size_t size, gfp_t gfp)
+{
+ struct drmres *dr;
+
+ dr = alloc_dr(NULL, size, gfp, dev_to_node(dev->dev));
+ if (!dr) {
+ drm_dbg_drmres(dev, "failed to allocate %zu bytes, %u flags\n",
+ size, gfp);
+ return NULL;
+ }
+ dr->node.name = kstrdup_const("kmalloc", GFP_KERNEL);
+
+ add_dr(dev, dr);
+
+ return dr->data;
+}
+EXPORT_SYMBOL(drmm_kmalloc);
+
+void drmm_kfree(struct drm_device *dev, void *data)
+{
+ struct drmres *dr_match = NULL, *dr;
+ unsigned long flags;
+
+ if (!data)
+ return;
+
+ spin_lock_irqsave(&dev->managed.lock, flags);
+ list_for_each_entry(dr, &dev->managed.resources, node.entry) {
+ if (dr->data == data) {
+ dr_match = dr;
+ del_dr(dev, dr_match);
+ break;
+ }
+ }
+ spin_unlock_irqrestore(&dev->managed.lock, flags);
+
+ if (WARN_ON(!dr_match))
+ return;
+
+ free_dr(dr_match);
+}
+EXPORT_SYMBOL(drmm_kfree);