Refactored eb_relocate_vma to simplify stack access and loop structure.
No functional changes; this is a readability and clarity improvement only.
Signed-off-by: Sebastian Brzezinka <sebastian.brzezi...@intel.com>
---
v1 -> v2:
- Revert changes in error handling.
- Restore the original formatting of the comments.
- Reword commit message.
---
.../gpu/drm/i915/gem/i915_gem_execbuffer.c | 84 ++++++++++---------
1 file changed, 44 insertions(+), 40 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index ca7e9216934a..ea4793e73ea5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1529,6 +1529,7 @@ static int eb_relocate_vma(struct i915_execbuffer *eb,
struct eb_vma *ev)
struct drm_i915_gem_relocation_entry __user *urelocs =
u64_to_user_ptr(entry->relocs_ptr);
unsigned long remain = entry->relocation_count;
+ int ret = 0;
if (unlikely(remain > N_RELOC(INT_MAX)))
return -EINVAL;
@@ -1541,11 +1542,10 @@ static int eb_relocate_vma(struct i915_execbuffer *eb,
struct eb_vma *ev)
if (unlikely(!access_ok(urelocs, remain * sizeof(*urelocs))))
return -EFAULT;
- do {
- struct drm_i915_gem_relocation_entry *r = stack;
- unsigned int count =
- min_t(unsigned long, remain, ARRAY_SIZE(stack));
+ while (remain > 0) {
+ unsigned int count = min_t(unsigned long, remain,
ARRAY_SIZE(stack));
unsigned int copied;
+ unsigned int i;
/*
* This is the fast path and we cannot handle a pagefault
@@ -1556,53 +1556,57 @@ static int eb_relocate_vma(struct i915_execbuffer *eb,
struct eb_vma *ev)
* this is bad and so lockdep complains vehemently.
*/
pagefault_disable();
- copied = __copy_from_user_inatomic(r, urelocs, count *
sizeof(r[0]));
+ copied = __copy_from_user_inatomic(stack, urelocs, count *
sizeof(stack[0]));
pagefault_enable();
+
if (unlikely(copied)) {
- remain = -EFAULT;
+ ret = -EFAULT;
goto out;
}
- remain -= count;
- do {
+ for (i = 0; i < count; ++i) {
+ struct drm_i915_gem_relocation_entry *r = &stack[i];
u64 offset = eb_relocate_entry(eb, ev, r);
- if (likely(offset == 0)) {
- } else if ((s64)offset < 0) {
- remain = (int)offset;
+ if (likely(offset == 0))
+ continue;
+
+ if (unlikely((s64)offset < 0)) {
+ ret = (int)offset;
goto out;
- } else {
- /*
- * Note that reporting an error now
- * leaves everything in an inconsistent
- * state as we have *already* changed
- * the relocation value inside the
- * object. As we have not changed the
- * reloc.presumed_offset or will not
- * change the execobject.offset, on the
- * call we may not rewrite the value
- * inside the object, leaving it
- * dangling and causing a GPU hang. Unless
- * userspace dynamically rebuilds the
- * relocations on each execbuf rather than
- * presume a static tree.
- *
- * We did previously check if the relocations
- * were writable (access_ok), an error now
- * would be a strange race with mprotect,
- * having already demonstrated that we
- * can read from this userspace address.
- */
- offset = gen8_canonical_addr(offset & ~UPDATE);
- __put_user(offset,
- &urelocs[r - stack].presumed_offset);
}
- } while (r++, --count);
- urelocs += ARRAY_SIZE(stack);
- } while (remain);
+ /*
+ * Note that reporting an error now
+ * leaves everything in an inconsistent
+ * state as we have *already* changed
+ * the relocation value inside the
+ * object. As we have not changed the
+ * reloc.presumed_offset or will not
+ * change the execobject.offset, on the
+ * call we may not rewrite the value
+ * inside the object, leaving it
+ * dangling and causing a GPU hang. Unless
+ * userspace dynamically rebuilds the
+ * relocations on each execbuf rather than
+ * presume a static tree.
+ *
+ * We did previously check if the relocations
+ * were writable (access_ok), an error now
+ * would be a strange race with mprotect,
+ * having already demonstrated that we
+ * can read from this userspace address.
+ */
+ offset = gen8_canonical_addr(offset & ~UPDATE);
+ __put_user(offset, &urelocs[i].presumed_offset);
+ }
+
+ remain -= count;
+ urelocs += count;
+ }
+
out:
reloc_cache_reset(&eb->reloc_cache, eb);
- return remain;
+ return ret;
}
static int
--
2.34.1
