Livepatch uses ftrace for redirection to new patched functions. It means
that if ftrace is disabled, all live patched functions are disabled as
well. Toggling global 'ftrace_enabled' sysctl thus affect it directly.
It is not a problem per se, because only administrator can set sysctl
values, but it still may be surprising.
Introduce PERMANENT ftrace_ops flag to amend this. If the
FTRACE_OPS_FL_PERMANENT is set on any ftrace ops, the tracing cannot be
disabled by disabling ftrace_enabled. Equally, a callback with the flag
set cannot be registered if ftrace_enabled is disabled.
Link: http://lkml.kernel.org/r/20191016113316.13415-2-mbenes@suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
As we move stuff around, some doc references are broken. Fix some of
them via this script:
./scripts/documentation-file-ref-check --fix
Manually checked if the produced result is valid, removing a few
false-positives.
Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
This patch corrects some spelling typo in ftrace-users.rst
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Add ftrace-uses.rst into Sphinx TOC tree. Few format issues are fixed.
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Changbin Du <changbin.du@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
ftrace-uses.rst is not yet included into any toctree, but since it is
a .rst file, it is parsed by the Sphinx build. Thats, why we see some
WARNINGS:
- trace/ftrace-uses.rst:53: WARNING: Definition list ends without a blank line; unexpected unindent.
- trace/ftrace-uses.rst:89: WARNING: Inline emphasis start-string without end-string.
- trace/ftrace-uses.rst:89: WARNING: Inline emphasis start-string without end-strin
Fixing the code-block directives results in a less noisy build, but the 'not
included' WARNING will be stay:
- trace/ftrace-uses.rst: WARNING: document isn't included in any toctree
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
With the coming removal of jprobes, using ftrace callbacks is one of the
utilities that replace the jprobes functionality. Having a document that
explains how to use ftrace as such will help in the transition from jprobes
to ftrace. This document is for kernel developers that require attaching a
callback to a function within the kernel.
Link: http://lkml.kernel.org/r/150724519527.5014.10207042218696587159.stgit@devbox
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[jc: fixed one formatting issue that broke the docs build]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
