drm/ttm: Allocate the page pool manager in the heap.

Repeated ttm_page_alloc_init/fini fails noisily because the pool
manager kobj isn't zeroed out between uses (we could do just that but
statically allocated kobjects are generally considered a bad thing).
Move it to kzalloc'ed memory.

Note that this patch drops the refcounting behavior of the pool
allocator init/fini functions: it would have led to a race condition
in its current form, and anyway it was never exploited.

This fixes a regression with reloading kms modules at runtime, since
page allocator was introduced.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 33 insertions, 35 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c b/drivers/gpu/drm/ttm/ttm_page_alloc.c
index 2f047577b1e3..b1d67dc973dc 100644
--- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
+++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
@@ -104,7 +104,6 @@ struct ttm_pool_opts {
 struct ttm_pool_manager {
         struct kobject          kobj;
         struct shrinker         mm_shrink;
-        atomic_t                page_alloc_inited;
         struct ttm_pool_opts    options;
 
         union {
@@ -142,7 +141,7 @@ static void ttm_pool_kobj_release(struct kobject *kobj)
 {
         struct ttm_pool_manager *m =
                 container_of(kobj, struct ttm_pool_manager, kobj);
-        (void)m;
+        kfree(m);
 }
 
 static ssize_t ttm_pool_store(struct kobject *kobj,
@@ -214,9 +213,7 @@ static struct kobj_type ttm_pool_kobj_type = {
         .default_attrs = ttm_pool_attrs,
 };
 
-static struct ttm_pool_manager _manager = {
-        .page_alloc_inited      = ATOMIC_INIT(0)
-};
+static struct ttm_pool_manager *_manager;
 
 #ifndef CONFIG_X86
 static int set_pages_array_wb(struct page **pages, int addrinarray)
@@ -271,7 +268,7 @@ static struct ttm_page_pool *ttm_get_pool(int flags,
         if (flags & TTM_PAGE_FLAG_DMA32)
                 pool_index |= 0x2;
 
-        return &_manager.pools[pool_index];
+        return &_manager->pools[pool_index];
 }
 
 /* set memory back to wb and free the pages. */
@@ -387,7 +384,7 @@ static int ttm_pool_get_num_unused_pages(void)
         unsigned i;
         int total = 0;
         for (i = 0; i < NUM_POOLS; ++i)
-                total += _manager.pools[i].npages;
+                total += _manager->pools[i].npages;
 
         return total;
 }
@@ -408,7 +405,7 @@ static int ttm_pool_mm_shrink(int shrink_pages, gfp_t gfp_mask)
                 unsigned nr_free = shrink_pages;
                 if (shrink_pages == 0)
                         break;
-                pool = &_manager.pools[(i + pool_offset)%NUM_POOLS];
+                pool = &_manager->pools[(i + pool_offset)%NUM_POOLS];
                 shrink_pages = ttm_page_pool_free(pool, nr_free);
         }
         /* return estimated number of unused pages in pool */
@@ -576,10 +573,10 @@ static void ttm_page_pool_fill_locked(struct ttm_page_pool *pool,
 
         /* If allocation request is small and there is not enough
          * pages in pool we fill the pool first */
-        if (count < _manager.options.small
+        if (count < _manager->options.small
                 && count > pool->npages) {
                 struct list_head new_pages;
-                unsigned alloc_size = _manager.options.alloc_size;
+                unsigned alloc_size = _manager->options.alloc_size;
 
                 /**
                  * Can't change page caching if in irqsave context. We have to
@@ -759,8 +756,8 @@ void ttm_put_pages(struct list_head *pages, unsigned page_count, int flags,
         pool->npages += page_count;
         /* Check that we don't go over the pool limit */
         page_count = 0;
-        if (pool->npages > _manager.options.max_size) {
-                page_count = pool->npages - _manager.options.max_size;
+        if (pool->npages > _manager->options.max_size) {
+                page_count = pool->npages - _manager->options.max_size;
                 /* free at least NUM_PAGES_TO_ALLOC number of pages
                  * to reduce calls to set_memory_wb */
                 if (page_count < NUM_PAGES_TO_ALLOC)
@@ -785,33 +782,36 @@ static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, int flags,
 int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
 {
         int ret;
-        if (atomic_add_return(1, &_manager.page_alloc_inited) > 1)
-                return 0;
+
+        WARN_ON(_manager);
 
         printk(KERN_INFO TTM_PFX "Initializing pool allocator.\n");
 
-        ttm_page_pool_init_locked(&_manager.wc_pool, GFP_HIGHUSER, "wc");
+        _manager = kzalloc(sizeof(*_manager), GFP_KERNEL);
 
-        ttm_page_pool_init_locked(&_manager.uc_pool, GFP_HIGHUSER, "uc");
+        ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc");
 
-        ttm_page_pool_init_locked(&_manager.wc_pool_dma32, GFP_USER | GFP_DMA32,
-                        "wc dma");
+        ttm_page_pool_init_locked(&_manager->uc_pool, GFP_HIGHUSER, "uc");
 
-        ttm_page_pool_init_locked(&_manager.uc_pool_dma32, GFP_USER | GFP_DMA32,
-                        "uc dma");
+        ttm_page_pool_init_locked(&_manager->wc_pool_dma32,
+                                  GFP_USER | GFP_DMA32, "wc dma");
 
-        _manager.options.max_size = max_pages;
-        _manager.options.small = SMALL_ALLOCATION;
-        _manager.options.alloc_size = NUM_PAGES_TO_ALLOC;
+        ttm_page_pool_init_locked(&_manager->uc_pool_dma32,
+                                  GFP_USER | GFP_DMA32, "uc dma");
 
-        kobject_init(&_manager.kobj, &ttm_pool_kobj_type);
-        ret = kobject_add(&_manager.kobj, &glob->kobj, "pool");
+        _manager->options.max_size = max_pages;
+        _manager->options.small = SMALL_ALLOCATION;
+        _manager->options.alloc_size = NUM_PAGES_TO_ALLOC;
+
+        ret = kobject_init_and_add(&_manager->kobj, &ttm_pool_kobj_type,
+                                   &glob->kobj, "pool");
         if (unlikely(ret != 0)) {
-                kobject_put(&_manager.kobj);
+                kobject_put(&_manager->kobj);
+                _manager = NULL;
                 return ret;
         }
 
-        ttm_pool_mm_shrink_init(&_manager);
+        ttm_pool_mm_shrink_init(_manager);
 
         return 0;
 }
@@ -820,16 +820,14 @@ void ttm_page_alloc_fini()
 {
         int i;
 
-        if (atomic_sub_return(1, &_manager.page_alloc_inited) > 0)
-                return;
-
         printk(KERN_INFO TTM_PFX "Finalizing pool allocator.\n");
-        ttm_pool_mm_shrink_fini(&_manager);
+        ttm_pool_mm_shrink_fini(_manager);
 
         for (i = 0; i < NUM_POOLS; ++i)
-                ttm_page_pool_free(&_manager.pools[i], FREE_ALL_PAGES);
+                ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES);
 
-        kobject_put(&_manager.kobj);
+        kobject_put(&_manager->kobj);
+        _manager = NULL;
 }
 
 int ttm_page_alloc_debugfs(struct seq_file *m, void *data)
@@ -837,14 +835,14 @@ int ttm_page_alloc_debugfs(struct seq_file *m, void *data)
         struct ttm_page_pool *p;
         unsigned i;
         char *h[] = {"pool", "refills", "pages freed", "size"};
-        if (atomic_read(&_manager.page_alloc_inited) == 0) {
+        if (!_manager) {
                 seq_printf(m, "No pool allocator running.\n");
                 return 0;
         }
         seq_printf(m, "%6s %12s %13s %8s\n",
                         h[0], h[1], h[2], h[3]);
         for (i = 0; i < NUM_POOLS; ++i) {
-                p = &_manager.pools[i];
+                p = &_manager->pools[i];
 
                 seq_printf(m, "%6s %12ld %13ld %8d\n",
                                 p->name, p->nrefills,