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drm/i915: Add some selftests for sg_table manipulation
authorChris Wilson <chris@chris-wilson.co.uk>
Mon, 13 Feb 2017 17:15:13 +0000 (17:15 +0000)
committerChris Wilson <chris@chris-wilson.co.uk>
Mon, 13 Feb 2017 20:45:23 +0000 (20:45 +0000)
Start exercising the scattergather lists, especially looking at
iteration after coalescing.

v2: Comment on the peculiarity of table construction (i.e. why this
sg_table might be interesting).
v3: Added one __func__ to identify expect_pfn_sg()
v4: Loop until we have crossed the chain boundary (forcing sg_table to
do multiple allocations) before squelching a potential ENOMEM from oom.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-2-chris@chris-wilson.co.uk
drivers/gpu/drm/i915/i915_gem.c
drivers/gpu/drm/i915/selftests/i915_mock_selftests.h
drivers/gpu/drm/i915/selftests/scatterlist.c [new file with mode: 0644]

index 638b335..c91e5d1 100644 (file)
@@ -2224,17 +2224,17 @@ unlock:
        mutex_unlock(&obj->mm.lock);
 }
 
-static void i915_sg_trim(struct sg_table *orig_st)
+static bool i915_sg_trim(struct sg_table *orig_st)
 {
        struct sg_table new_st;
        struct scatterlist *sg, *new_sg;
        unsigned int i;
 
        if (orig_st->nents == orig_st->orig_nents)
-               return;
+               return false;
 
        if (sg_alloc_table(&new_st, orig_st->nents, GFP_KERNEL | __GFP_NOWARN))
-               return;
+               return false;
 
        new_sg = new_st.sgl;
        for_each_sg(orig_st->sgl, sg, orig_st->nents, i) {
@@ -2247,6 +2247,7 @@ static void i915_sg_trim(struct sg_table *orig_st)
        sg_free_table(orig_st);
 
        *orig_st = new_st;
+       return true;
 }
 
 static struct sg_table *
@@ -5019,3 +5020,7 @@ i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
        sg = i915_gem_object_get_sg(obj, n, &offset);
        return sg_dma_address(sg) + (offset << PAGE_SHIFT);
 }
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/scatterlist.c"
+#endif
index 69e97a2..5f0bdda 100644 (file)
@@ -9,3 +9,4 @@
  * Tests are executed in order by igt/drv_selftest
  */
 selftest(sanitycheck, i915_mock_sanitycheck) /* keep first (igt selfcheck) */
+selftest(scatterlist, scatterlist_mock_selftests)
diff --git a/drivers/gpu/drm/i915/selftests/scatterlist.c b/drivers/gpu/drm/i915/selftests/scatterlist.c
new file mode 100644 (file)
index 0000000..eb2cda8
--- /dev/null
@@ -0,0 +1,355 @@
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/prime_numbers.h>
+#include <linux/random.h>
+
+#include "../i915_selftest.h"
+
+#define PFN_BIAS (1 << 10)
+
+struct pfn_table {
+       struct sg_table st;
+       unsigned long start, end;
+};
+
+typedef unsigned int (*npages_fn_t)(unsigned long n,
+                                   unsigned long count,
+                                   struct rnd_state *rnd);
+
+static noinline int expect_pfn_sg(struct pfn_table *pt,
+                                 npages_fn_t npages_fn,
+                                 struct rnd_state *rnd,
+                                 const char *who,
+                                 unsigned long timeout)
+{
+       struct scatterlist *sg;
+       unsigned long pfn, n;
+
+       pfn = pt->start;
+       for_each_sg(pt->st.sgl, sg, pt->st.nents, n) {
+               struct page *page = sg_page(sg);
+               unsigned int npages = npages_fn(n, pt->st.nents, rnd);
+
+               if (page_to_pfn(page) != pfn) {
+                       pr_err("%s: %s left pages out of order, expected pfn %lu, found pfn %lu (using for_each_sg)\n",
+                              __func__, who, pfn, page_to_pfn(page));
+                       return -EINVAL;
+               }
+
+               if (sg->length != npages * PAGE_SIZE) {
+                       pr_err("%s: %s copied wrong sg length, expected size %lu, found %u (using for_each_sg)\n",
+                              __func__, who, npages * PAGE_SIZE, sg->length);
+                       return -EINVAL;
+               }
+
+               if (igt_timeout(timeout, "%s timed out\n", who))
+                       return -EINTR;
+
+               pfn += npages;
+       }
+       if (pfn != pt->end) {
+               pr_err("%s: %s finished on wrong pfn, expected %lu, found %lu\n",
+                      __func__, who, pt->end, pfn);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static noinline int expect_pfn_sg_page_iter(struct pfn_table *pt,
+                                           const char *who,
+                                           unsigned long timeout)
+{
+       struct sg_page_iter sgiter;
+       unsigned long pfn;
+
+       pfn = pt->start;
+       for_each_sg_page(pt->st.sgl, &sgiter, pt->st.nents, 0) {
+               struct page *page = sg_page_iter_page(&sgiter);
+
+               if (page != pfn_to_page(pfn)) {
+                       pr_err("%s: %s left pages out of order, expected pfn %lu, found pfn %lu (using for_each_sg_page)\n",
+                              __func__, who, pfn, page_to_pfn(page));
+                       return -EINVAL;
+               }
+
+               if (igt_timeout(timeout, "%s timed out\n", who))
+                       return -EINTR;
+
+               pfn++;
+       }
+       if (pfn != pt->end) {
+               pr_err("%s: %s finished on wrong pfn, expected %lu, found %lu\n",
+                      __func__, who, pt->end, pfn);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static noinline int expect_pfn_sgtiter(struct pfn_table *pt,
+                                      const char *who,
+                                      unsigned long timeout)
+{
+       struct sgt_iter sgt;
+       struct page *page;
+       unsigned long pfn;
+
+       pfn = pt->start;
+       for_each_sgt_page(page, sgt, &pt->st) {
+               if (page != pfn_to_page(pfn)) {
+                       pr_err("%s: %s left pages out of order, expected pfn %lu, found pfn %lu (using for_each_sgt_page)\n",
+                              __func__, who, pfn, page_to_pfn(page));
+                       return -EINVAL;
+               }
+
+               if (igt_timeout(timeout, "%s timed out\n", who))
+                       return -EINTR;
+
+               pfn++;
+       }
+       if (pfn != pt->end) {
+               pr_err("%s: %s finished on wrong pfn, expected %lu, found %lu\n",
+                      __func__, who, pt->end, pfn);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static int expect_pfn_sgtable(struct pfn_table *pt,
+                             npages_fn_t npages_fn,
+                             struct rnd_state *rnd,
+                             const char *who,
+                             unsigned long timeout)
+{
+       int err;
+
+       err = expect_pfn_sg(pt, npages_fn, rnd, who, timeout);
+       if (err)
+               return err;
+
+       err = expect_pfn_sg_page_iter(pt, who, timeout);
+       if (err)
+               return err;
+
+       err = expect_pfn_sgtiter(pt, who, timeout);
+       if (err)
+               return err;
+
+       return 0;
+}
+
+static unsigned int one(unsigned long n,
+                       unsigned long count,
+                       struct rnd_state *rnd)
+{
+       return 1;
+}
+
+static unsigned int grow(unsigned long n,
+                        unsigned long count,
+                        struct rnd_state *rnd)
+{
+       return n + 1;
+}
+
+static unsigned int shrink(unsigned long n,
+                          unsigned long count,
+                          struct rnd_state *rnd)
+{
+       return count - n;
+}
+
+static unsigned int random(unsigned long n,
+                          unsigned long count,
+                          struct rnd_state *rnd)
+{
+       return 1 + (prandom_u32_state(rnd) % 1024);
+}
+
+static int alloc_table(struct pfn_table *pt,
+                      unsigned long count, unsigned long max,
+                      npages_fn_t npages_fn,
+                      struct rnd_state *rnd,
+                      int alloc_error)
+{
+       struct scatterlist *sg;
+       unsigned long n, pfn;
+
+       if (sg_alloc_table(&pt->st, max,
+                          GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN))
+               return alloc_error;
+
+       /* count should be less than 20 to prevent overflowing sg->length */
+       GEM_BUG_ON(overflows_type(count * PAGE_SIZE, sg->length));
+
+       /* Construct a table where each scatterlist contains different number
+        * of entries. The idea is to check that we can iterate the individual
+        * pages from inside the coalesced lists.
+        */
+       pt->start = PFN_BIAS;
+       pfn = pt->start;
+       sg = pt->st.sgl;
+       for (n = 0; n < count; n++) {
+               unsigned long npages = npages_fn(n, count, rnd);
+
+               /* Nobody expects the Sparse Memmap! */
+               if (pfn_to_page(pfn + npages) != pfn_to_page(pfn) + npages) {
+                       sg_free_table(&pt->st);
+                       return -ENOSPC;
+               }
+
+               if (n)
+                       sg = sg_next(sg);
+               sg_set_page(sg, pfn_to_page(pfn), npages * PAGE_SIZE, 0);
+
+               GEM_BUG_ON(page_to_pfn(sg_page(sg)) != pfn);
+               GEM_BUG_ON(sg->length != npages * PAGE_SIZE);
+               GEM_BUG_ON(sg->offset != 0);
+
+               pfn += npages;
+       }
+       sg_mark_end(sg);
+       pt->st.nents = n;
+       pt->end = pfn;
+
+       return 0;
+}
+
+static const npages_fn_t npages_funcs[] = {
+       one,
+       grow,
+       shrink,
+       random,
+       NULL,
+};
+
+static int igt_sg_alloc(void *ignored)
+{
+       IGT_TIMEOUT(end_time);
+       const unsigned long max_order = 20; /* approximating a 4GiB object */
+       struct rnd_state prng;
+       unsigned long prime;
+       int alloc_error = -ENOMEM;
+
+       for_each_prime_number(prime, max_order) {
+               unsigned long size = BIT(prime);
+               int offset;
+
+               for (offset = -1; offset <= 1; offset++) {
+                       unsigned long sz = size + offset;
+                       const npages_fn_t *npages;
+                       struct pfn_table pt;
+                       int err;
+
+                       for (npages = npages_funcs; *npages; npages++) {
+                               prandom_seed_state(&prng,
+                                                  i915_selftest.random_seed);
+                               err = alloc_table(&pt, sz, sz, *npages, &prng,
+                                                 alloc_error);
+                               if (err == -ENOSPC)
+                                       break;
+                               if (err)
+                                       return err;
+
+                               prandom_seed_state(&prng,
+                                                  i915_selftest.random_seed);
+                               err = expect_pfn_sgtable(&pt, *npages, &prng,
+                                                        "sg_alloc_table",
+                                                        end_time);
+                               sg_free_table(&pt.st);
+                               if (err)
+                                       return err;
+                       }
+               }
+
+               /* Test at least one continuation before accepting oom */
+               if (size > SG_MAX_SINGLE_ALLOC)
+                       alloc_error = -ENOSPC;
+       }
+
+       return 0;
+}
+
+static int igt_sg_trim(void *ignored)
+{
+       IGT_TIMEOUT(end_time);
+       const unsigned long max = PAGE_SIZE; /* not prime! */
+       struct pfn_table pt;
+       unsigned long prime;
+       int alloc_error = -ENOMEM;
+
+       for_each_prime_number(prime, max) {
+               const npages_fn_t *npages;
+               int err;
+
+               for (npages = npages_funcs; *npages; npages++) {
+                       struct rnd_state prng;
+
+                       prandom_seed_state(&prng, i915_selftest.random_seed);
+                       err = alloc_table(&pt, prime, max, *npages, &prng,
+                                         alloc_error);
+                       if (err == -ENOSPC)
+                               break;
+                       if (err)
+                               return err;
+
+                       if (i915_sg_trim(&pt.st)) {
+                               if (pt.st.orig_nents != prime ||
+                                   pt.st.nents != prime) {
+                                       pr_err("i915_sg_trim failed (nents %u, orig_nents %u), expected %lu\n",
+                                              pt.st.nents, pt.st.orig_nents, prime);
+                                       err = -EINVAL;
+                               } else {
+                                       prandom_seed_state(&prng,
+                                                          i915_selftest.random_seed);
+                                       err = expect_pfn_sgtable(&pt,
+                                                                *npages, &prng,
+                                                                "i915_sg_trim",
+                                                                end_time);
+                               }
+                       }
+                       sg_free_table(&pt.st);
+                       if (err)
+                               return err;
+               }
+
+               /* Test at least one continuation before accepting oom */
+               if (prime > SG_MAX_SINGLE_ALLOC)
+                       alloc_error = -ENOSPC;
+       }
+
+       return 0;
+}
+
+int scatterlist_mock_selftests(void)
+{
+       static const struct i915_subtest tests[] = {
+               SUBTEST(igt_sg_alloc),
+               SUBTEST(igt_sg_trim),
+       };
+
+       return i915_subtests(tests, NULL);
+}