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[4.19,047/168] gpu: host1x: debug: Fix multiple channels emitting messages simultaneously

Message ID 20200817143736.104308167@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Aug. 17, 2020, 3:16 p.m. UTC 
From: Dmitry Osipenko <digetx@gmail.com>

[ Upstream commit 35681862808472a0a4b9a8817ae2789c0b5b3edc ]

Once channel's job is hung, it dumps the channel's state into KMSG before
tearing down the offending job. If multiple channels hang at once, then
they dump messages simultaneously, making the debug info unreadable, and
thus, useless. This patch adds mutex which allows only one channel to emit
debug messages at a time.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/host1x/debug.c | 4 ++++
 1 file changed, 4 insertions(+)
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Patch

diff --git a/drivers/gpu/host1x/debug.c b/drivers/gpu/host1x/debug.c
index 329e4a3d8ae7b..6c9ad4533999c 100644
--- a/drivers/gpu/host1x/debug.c
+++ b/drivers/gpu/host1x/debug.c
@@ -25,6 +25,8 @@ 
 #include "debug.h"
 #include "channel.h"
 
+static DEFINE_MUTEX(debug_lock);
+
 unsigned int host1x_debug_trace_cmdbuf;
 
 static pid_t host1x_debug_force_timeout_pid;
@@ -61,12 +63,14 @@  static int show_channel(struct host1x_channel *ch, void *data, bool show_fifo)
 	struct output *o = data;
 
 	mutex_lock(&ch->cdma.lock);
+	mutex_lock(&debug_lock);
 
 	if (show_fifo)
 		host1x_hw_show_channel_fifo(m, ch, o);
 
 	host1x_hw_show_channel_cdma(m, ch, o);
 
+	mutex_unlock(&debug_lock);
 	mutex_unlock(&ch->cdma.lock);
 
 	return 0;