drm: Protect dev->filelist with its own mutex

amdgpu gained dev->struct_mutex usage, and that's because it's walking
the dev->filelist list. Protect that list with it's own lock to take
one more step towards getting rid of struct_mutex usage in drivers
once and for all.

While doing the conversion I noticed that 2 debugfs files in i915
completely lacked appropriate locking. Fix that up too.

v2: don't forget to switch to drm_gem_object_unreference_unlocked.

Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461691808-12414-9-git-send-email-daniel.vetter@ffwll.ch

6 files changed, 25 insertions, 12 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index fa6a27bff298..a087b9638cde 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -93,7 +93,7 @@ void amdgpu_gem_force_release(struct amdgpu_device *adev)
         struct drm_device *ddev = adev->ddev;
         struct drm_file *file;
 
-        mutex_lock(&ddev->struct_mutex);
+        mutex_lock(&ddev->filelist_mutex);
 
         list_for_each_entry(file, &ddev->filelist, lhead) {
                 struct drm_gem_object *gobj;
@@ -103,13 +103,13 @@ void amdgpu_gem_force_release(struct amdgpu_device *adev)
                 spin_lock(&file->table_lock);
                 idr_for_each_entry(&file->object_idr, gobj, handle) {
                         WARN_ONCE(1, "And also active allocations!\n");
-                        drm_gem_object_unreference(gobj);
+                        drm_gem_object_unreference_unlocked(gobj);
                 }
                 idr_destroy(&file->object_idr);
                 spin_unlock(&file->table_lock);
         }
 
-        mutex_unlock(&ddev->struct_mutex);
+        mutex_unlock(&ddev->filelist_mutex);
 }
 
 /*
@@ -769,7 +769,7 @@ static int amdgpu_debugfs_gem_info(struct seq_file *m, void *data)
         struct drm_file *file;
         int r;
 
-        r = mutex_lock_interruptible(&dev->struct_mutex);
+        r = mutex_lock_interruptible(&dev->filelist_mutex);
         if (r)
                 return r;
 
@@ -793,7 +793,7 @@ static int amdgpu_debugfs_gem_info(struct seq_file *m, void *data)
                 spin_unlock(&file->table_lock);
         }
 
-        mutex_unlock(&dev->struct_mutex);
+        mutex_unlock(&dev->filelist_mutex);
         return 0;
 }
 
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index e1fb52d4f72c..bff89226a344 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -590,6 +590,7 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
         spin_lock_init(&dev->buf_lock);
         spin_lock_init(&dev->event_lock);
         mutex_init(&dev->struct_mutex);
+        mutex_init(&dev->filelist_mutex);
         mutex_init(&dev->ctxlist_mutex);
         mutex_init(&dev->master_mutex);
 
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index c3d0aaac0669..7af7f8bcb355 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -297,9 +297,9 @@ static int drm_open_helper(struct file *filp, struct drm_minor *minor)
         }
         mutex_unlock(&dev->master_mutex);
 
-        mutex_lock(&dev->struct_mutex);
+        mutex_lock(&dev->filelist_mutex);
         list_add(&priv->lhead, &dev->filelist);
-        mutex_unlock(&dev->struct_mutex);
+        mutex_unlock(&dev->filelist_mutex);
 
 #ifdef __alpha__
         /*
@@ -447,8 +447,11 @@ int drm_release(struct inode *inode, struct file *filp)
 
         DRM_DEBUG("open_count = %d\n", dev->open_count);
 
-        mutex_lock(&dev->struct_mutex);
+        mutex_lock(&dev->filelist_mutex);
         list_del(&file_priv->lhead);
+        mutex_unlock(&dev->filelist_mutex);
+
+        mutex_lock(&dev->struct_mutex);
         if (file_priv->magic)
                 idr_remove(&file_priv->master->magic_map, file_priv->magic);
         mutex_unlock(&dev->struct_mutex);
diff --git a/drivers/gpu/drm/drm_info.c b/drivers/gpu/drm/drm_info.c
index cbb4fc0fc969..5d469b2f26f4 100644
--- a/drivers/gpu/drm/drm_info.c
+++ b/drivers/gpu/drm/drm_info.c
@@ -174,7 +174,7 @@ int drm_clients_info(struct seq_file *m, void *data)
         /* dev->filelist is sorted youngest first, but we want to present
          * oldest first (i.e. kernel, servers, clients), so walk backwardss.
          */
-        mutex_lock(&dev->struct_mutex);
+        mutex_lock(&dev->filelist_mutex);
         list_for_each_entry_reverse(priv, &dev->filelist, lhead) {
                 struct task_struct *task;
 
@@ -190,7 +190,7 @@ int drm_clients_info(struct seq_file *m, void *data)
                            priv->magic);
                 rcu_read_unlock();
         }
-        mutex_unlock(&dev->struct_mutex);
+        mutex_unlock(&dev->filelist_mutex);
         return 0;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 85933940fe9c..c298312f83f6 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -498,6 +498,10 @@ static int i915_gem_object_info(struct seq_file *m, void* data)
 
         seq_putc(m, '\n');
         print_batch_pool_stats(m, dev_priv);
+
+        mutex_unlock(&dev->struct_mutex);
+
+        mutex_lock(&dev->filelist_mutex);
         list_for_each_entry_reverse(file, &dev->filelist, lhead) {
                 struct file_stats stats;
                 struct task_struct *task;
@@ -518,8 +522,7 @@ static int i915_gem_object_info(struct seq_file *m, void* data)
                 print_file_stats(m, task ? task->comm : "<unknown>", stats);
                 rcu_read_unlock();
         }
-
-        mutex_unlock(&dev->struct_mutex);
+        mutex_unlock(&dev->filelist_mutex);
 
         return 0;
 }
@@ -2325,6 +2328,7 @@ static int i915_ppgtt_info(struct seq_file *m, void *data)
         else if (INTEL_INFO(dev)->gen >= 6)
                 gen6_ppgtt_info(m, dev);
 
+        mutex_lock(&dev->filelist_mutex);
         list_for_each_entry_reverse(file, &dev->filelist, lhead) {
                 struct drm_i915_file_private *file_priv = file->driver_priv;
                 struct task_struct *task;
@@ -2339,6 +2343,7 @@ static int i915_ppgtt_info(struct seq_file *m, void *data)
                 idr_for_each(&file_priv->context_idr, per_file_ctx,
                              (void *)(unsigned long)m);
         }
+        mutex_unlock(&dev->filelist_mutex);
 
 out_put:
         intel_runtime_pm_put(dev_priv);
@@ -2374,6 +2379,8 @@ static int i915_rps_boost_info(struct seq_file *m, void *data)
                    intel_gpu_freq(dev_priv, dev_priv->rps.min_freq_softlimit),
                    intel_gpu_freq(dev_priv, dev_priv->rps.max_freq_softlimit),
                    intel_gpu_freq(dev_priv, dev_priv->rps.max_freq));
+
+        mutex_lock(&dev->filelist_mutex);
         spin_lock(&dev_priv->rps.client_lock);
         list_for_each_entry_reverse(file, &dev->filelist, lhead) {
                 struct drm_i915_file_private *file_priv = file->driver_priv;
@@ -2396,6 +2403,7 @@ static int i915_rps_boost_info(struct seq_file *m, void *data)
                    list_empty(&dev_priv->rps.mmioflips.link) ? "" : ", active");
         seq_printf(m, "Kernel boosts: %d\n", dev_priv->rps.boosts);
         spin_unlock(&dev_priv->rps.client_lock);
+        mutex_unlock(&dev->filelist_mutex);
 
         return 0;
 }
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 5de4cff05ac9..7901768bb47c 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -769,6 +769,7 @@ struct drm_device {
         atomic_t buf_alloc;             /**< Buffer allocation in progress */
         /*@} */
 
+        struct mutex filelist_mutex;
         struct list_head filelist;
 
         /** \name Memory management */