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Miroslav Benes
7162431dcf
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]>