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dbginfo.sh: fix accidental ftrace buffer shrinkage/free

Browse Source 
https://www.kernel.org/doc/html/latest/trace/ftrace.html?highlight=free_buffer

  free_buffer:

        If a process is performing tracing, and the ring buffer should be
        shrunk "freed" when the process is finished, even if it were to be
        killed by a signal, this file can be used for that purpose. On close
        of this file, the ring buffer will be resized to its minimum size.
        Having a process that is tracing also open this file, when the process
        exits its file descriptor for this file will be closed, and in doing so,
        the ring buffer will be "freed".

        It may also stop tracing if disable_on_free option is set.

$ cat /sys/kernel/debug/tracing/buffer_size_kb
7 (expanded: 1408)
$ cat /sys/kernel/debug/tracing/free_buffer
cat: /sys/kernel/debug/tracing/free_buffer: Invalid argument
$ cat /sys/kernel/debug/tracing/buffer_size_kb
0

Reported-by: Thomas Lambart <Thomas.Lambart2@ibm.com>
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Steffen Maier
2022-06-23 18:52:02 +02:00
committed by Jan Höppner
parent cd5d6a5004
commit eeed384a51
1 changed files with 2 additions and 0 deletions
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2
scripts/dbginfo.sh
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@@ -786,6 +786,7 @@ collect_sysfs() {
-x '*/tracing/trace_pipe*' \
-x '*/page_idle/bitmap*' \
-x '*/tracing/per_cpu/*' \
-x '*/tracing/free_buffer' \
--ignore-failed-read -J 1 -T 5 2>>${OUTPUT_FILE_SYSFS}.err
rc=$?
else
@@ -812,6 +813,7 @@ collect_sysfs() {
-a -not \( -path '*tracing*' -a -name "trace_pipe*" \) \
-a -not \( -path '*page_idle*' -a -name 'bitmap*' \) \
-a -not -path '*tracing/per_cpu*' \
-a -not -path '*/tracing/free_buffer' \
2>/dev/null | while IFS= read -r file_name; do
echo " ${file_name}"
if ! dd if="${file_name}" status=noxfer iflag=nonblock \