drm/i915: Show i915_gem_context owner in debugfs

Print the context's owner (via the pid under file_priv) under debugfs.
In doing so, we must be careful that the filp is not accessed after it
is freed (notified via i915_gem_context_close).

v2: Mark the file_priv as closed.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1464098023-3294-6-git-send-email-chris@chris-wilson.co.uk

2 files changed, 18 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 424e11efa3e1..05b9e5e0ee10 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -2014,9 +2014,23 @@ static int i915_context_status(struct seq_file *m, void *unused)
                         continue;
 
                 seq_printf(m, "HW context %u ", ctx->hw_id);
+                if (IS_ERR(ctx->file_priv)) {
+                        seq_puts(m, "(deleted) ");
+                } else if (ctx->file_priv) {
+                        struct pid *pid = ctx->file_priv->file->pid;
+                        struct task_struct *task;
+
+                        task = get_pid_task(pid, PIDTYPE_PID);
+                        if (task) {
+                                seq_printf(m, "(%s [%d]) ",
+                                           task->comm, task->pid);
+                                put_task_struct(task);
+                        }
+                } else {
+                        seq_puts(m, "(kernel) ");
+                }
+
                 describe_ctx(m, ctx);
-                if (ctx == dev_priv->kernel_context)
-                        seq_printf(m, "(kernel context) ");
 
                 if (i915.enable_execlists) {
                         seq_putc(m, '\n');
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 104d4819aca8..8d8c79b88816 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -468,6 +468,7 @@ static int context_idr_cleanup(int id, void *p, void *data)
 {
         struct i915_gem_context *ctx = p;
 
+        ctx->file_priv = ERR_PTR(-EBADF);
         i915_gem_context_unreference(ctx);
         return 0;
 }
@@ -938,7 +939,7 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
                 return PTR_ERR(ctx);
         }
 
-        idr_remove(&ctx->file_priv->context_idr, ctx->user_handle);
+        idr_remove(&file_priv->context_idr, ctx->user_handle);
         i915_gem_context_unreference(ctx);
         mutex_unlock(&dev->struct_mutex);