ftrace: Introduce PERMANENT ftrace_ops flag

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/[email protected]

Reviewed-by: Petr Mladek <[email protected]>
Reviewed-by: Kamalesh Babulal <[email protected]>
Signed-off-by: Miroslav Benes <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

0 files changed, 0 insertions, 0 deletions