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[PATCH 0/3] [GIT PULL] tracing: Minor fixes for 4.14 (and stable)

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  [PATCH 0/3] [GIT PULL] tracing: Minor fixes for 4.14 (and stable) Steven Rostedt <rostedt@goodmis.org> - 2017-09-20 15:40 +0200
    [PATCH 3/3] tracing: Fix trace_pipe behavior for instance traces Steven Rostedt <rostedt@goodmis.org> - 2017-09-20 15:40 +0200
    [PATCH 1/3] tracing: Erase irqsoff trace with empty write Steven Rostedt <rostedt@goodmis.org> - 2017-09-20 15:40 +0200

#1735768 — [PATCH 0/3] [GIT PULL] tracing: Minor fixes for 4.14 (and stable)

Linus,

This includes 3 minor fixes.

 - Have writing to trace file clear the irqsoff (and friends) tracer

 - trace_pipe behavior for instance buffers was different than top buffer

 - Show a message of why mmiotrace doesn't start from commandline

Please pull the latest trace-v4.14-rc1 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
trace-v4.14-rc1

Tag SHA1: cd68d5e5af1d4b58d32f937d7a59d15e88de3e4e
Head SHA1: 75df6e688ccd517e339a7c422ef7ad73045b18a2


Bo Yan (1):
      tracing: Erase irqsoff trace with empty write

Tahsin Erdogan (1):
      tracing: Fix trace_pipe behavior for instance traces

Ziqian SUN (Zamir) (1):
      tracing: Ignore mmiotrace from kernel commandline

----
 kernel/trace/trace.c           | 19 ++++++++++++++++---
 kernel/trace/trace.h           |  2 ++
 kernel/trace/trace_mmiotrace.c |  1 +
 3 files changed, 19 insertions(+), 3 deletions(-)

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#1735770 — [PATCH 3/3] tracing: Fix trace_pipe behavior for instance traces

From: Tahsin Erdogan <tahsin@google.com>

When reading data from trace_pipe, tracing_wait_pipe() performs a
check to see if tracing has been turned off after some data was read.
Currently, this check always looks at global trace state, but it
should be checking the trace instance where trace_pipe is located at.

Because of this bug, cat instances/i1/trace_pipe in the following
script will immediately exit instead of waiting for data:

cd /sys/kernel/debug/tracing
echo 0 > tracing_on
mkdir -p instances/i1
echo 1 > instances/i1/tracing_on
echo 1 > instances/i1/events/sched/sched_process_exec/enable
cat instances/i1/trace_pipe

Link: http://lkml.kernel.org/r/20170917102348.1615-1-tahsin@google.com

Cc: stable@vger.kernel.org
Fixes: 10246fa35d4f ("tracing: give easy way to clear trace buffer")
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d3ca35f38803..752e5daf0896 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5680,7 +5680,7 @@ static int tracing_wait_pipe(struct file *filp)
 		 *
 		 * iter->pos will be 0 if we haven't read anything.
 		 */
-		if (!tracing_is_on() && iter->pos)
+		if (!tracer_tracing_is_on(iter->tr) && iter->pos)
 			break;
 
 		mutex_unlock(&iter->mutex);
-- 
2.13.2

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#1735771 — [PATCH 1/3] tracing: Erase irqsoff trace with empty write

From: Bo Yan <byan@nvidia.com>

One convenient way to erase trace is "echo > trace". However, this
is currently broken if the current tracer is irqsoff tracer. This
is because irqsoff tracer use max_buffer as the default trace
buffer.

Set the max_buffer as the one to be cleared when it's the trace
buffer currently in use.

Link: http://lkml.kernel.org/r/1505754215-29411-1-git-send-email-byan@nvidia.com

Cc: <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 4acd4d00f ("tracing: give easy way to clear trace buffer")
Signed-off-by: Bo Yan <byan@nvidia.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5360b7aec57a..a7fb136da891 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4020,11 +4020,17 @@ static int tracing_open(struct inode *inode, struct file *file)
 	/* If this file was open for write, then erase contents */
 	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
 		int cpu = tracing_get_cpu(inode);
+		struct trace_buffer *trace_buf = &tr->trace_buffer;
+
+#ifdef CONFIG_TRACER_MAX_TRACE
+		if (tr->current_trace->print_max)
+			trace_buf = &tr->max_buffer;
+#endif
 
 		if (cpu == RING_BUFFER_ALL_CPUS)
-			tracing_reset_online_cpus(&tr->trace_buffer);
+			tracing_reset_online_cpus(trace_buf);
 		else
-			tracing_reset(&tr->trace_buffer, cpu);
+			tracing_reset(trace_buf, cpu);
 	}
 
 	if (file->f_mode & FMODE_READ) {
-- 
2.13.2

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