[RFC 3/3] drm/msm: Add comm/cmdline fields

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

Normally this would be the same information that can be obtained in
other ways.  But in some cases the process opening the drm fd is merely
a sort of proxy for the actual process using the GPU.  This is the case
for guest VM processes using the GPU via virglrenderer, in which case
the msm native-context renderer in virglrenderer overrides the comm/
cmdline to be the guest process's values.

Exposing this via fdinfo allows tools like gputop to show something more
meaningful than just a bunch of "pcivirtio-gpu" users.

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
 Documentation/gpu/drm-usage-stats.rst |  8 ++++++++
 drivers/gpu/drm/msm/msm_gpu.c         | 14 ++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/Documentation/gpu/drm-usage-stats.rst b/Documentation/gpu/drm-usage-stats.rst
index 8e00d53231e0..bc90bed455e3 100644
--- a/Documentation/gpu/drm-usage-stats.rst
+++ b/Documentation/gpu/drm-usage-stats.rst
@@ -148,6 +148,14 @@ percentage utilization of the engine, whereas drm-engine-<keystr> only reflects
 time active without considering what frequency the engine is operating as a
 percentage of it's maximum frequency.
 
+- drm-comm: <valstr>
+
+Returns the clients executable path.
+
+- drm-cmdline: <valstr>
+
+Returns the clients cmdline.
+
 Implementation Details
 ======================
 
diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index f0f4f845c32d..1150dcbf28aa 100644
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -148,12 +148,26 @@ int msm_gpu_pm_suspend(struct msm_gpu *gpu)
 	return 0;
 }
 
+static void get_comm_cmdline(struct msm_file_private *ctx, char **comm, char **cmd);
+
 void msm_gpu_show_fdinfo(struct msm_gpu *gpu, struct msm_file_private *ctx,
 			 struct drm_printer *p)
 {
+	char *comm, *cmdline;
+
+	get_comm_cmdline(ctx, &comm, &cmdline);
+
 	drm_printf(p, "drm-engine-gpu:\t%llu ns\n", ctx->elapsed_ns);
 	drm_printf(p, "drm-cycles-gpu:\t%llu\n", ctx->cycles);
 	drm_printf(p, "drm-maxfreq-gpu:\t%u Hz\n", gpu->fast_rate);
+
+	if (comm)
+		drm_printf(p, "drm-comm:\t%s\n", comm);
+	if (cmdline)
+		drm_printf(p, "drm-cmdline:\t%s\n", cmdline);
+
+	kfree(comm);
+	kfree(cmdline);
 }
 
 int msm_gpu_hw_init(struct msm_gpu *gpu)
-- 
2.39.2