dma-buf: fix inconsistent debug print v2

Drop the whole rcu handling since we are holding the resv lock anyway.

v2: drop all rcu handling instead.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602140359.272601-1-christian.koenig@amd.com

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index eadd1eaa2fb541cd4eaff428b8d53865619ea5ad..ee04fb4420156c88101e3ea7bc5e5bc8a9e94907 100644 (file)
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1349,15 +1349,14 @@ EXPORT_SYMBOL_GPL(dma_buf_vunmap);
 #ifdef CONFIG_DEBUG_FS
 static int dma_buf_debug_show(struct seq_file *s, void *unused)
 {
-       int ret;
        struct dma_buf *buf_obj;
        struct dma_buf_attachment *attach_obj;
        struct dma_resv *robj;
        struct dma_resv_list *fobj;
        struct dma_fence *fence;
-       unsigned seq;
        int count = 0, attach_count, shared_count, i;
        size_t size = 0;
+       int ret;
 
        ret = mutex_lock_interruptible(&db_list.lock);
 
@@ -1383,33 +1382,25 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
                                buf_obj->name ?: "");
 
                robj = buf_obj->resv;
-               while (true) {
-                       seq = read_seqcount_begin(&robj->seq);
-                       rcu_read_lock();
-                       fobj = rcu_dereference(robj->fence);
-                       shared_count = fobj ? fobj->shared_count : 0;
-                       fence = rcu_dereference(robj->fence_excl);
-                       if (!read_seqcount_retry(&robj->seq, seq))
-                               break;
-                       rcu_read_unlock();
-               }
-
+               fence = rcu_dereference_protected(robj->fence_excl,
+                                                 dma_resv_held(robj));
                if (fence)
                        seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",
                                   fence->ops->get_driver_name(fence),
                                   fence->ops->get_timeline_name(fence),
                                   dma_fence_is_signaled(fence) ? "" : "un");
+
+               fobj = rcu_dereference_protected(robj->fence,
+                                                dma_resv_held(robj));
+               shared_count = fobj ? fobj->shared_count : 0;
                for (i = 0; i < shared_count; i++) {
-                       fence = rcu_dereference(fobj->shared[i]);
-                       if (!dma_fence_get_rcu(fence))
-                               continue;
+                       fence = rcu_dereference_protected(fobj->shared[i],
+                                                         dma_resv_held(robj));
                        seq_printf(s, "\tShared fence: %s %s %ssignalled\n",
                                   fence->ops->get_driver_name(fence),
                                   fence->ops->get_timeline_name(fence),
                                   dma_fence_is_signaled(fence) ? "" : "un");
-                       dma_fence_put(fence);
                }
-               rcu_read_unlock();
 
                seq_puts(s, "\tAttached Devices:\n");
                attach_count = 0;