Messages in this thread | | | Date | Thu, 19 Feb 2009 17:32:10 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 4/6] ftrace, x86: make kernel text writable only for conversions |
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On Thu, 19 Feb 2009 20:13:20 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> +int ftrace_arch_modify_prepare(void) > +{ > + /* at boot up, we are still writable */ > + if (system_state != SYSTEM_RUNNING) > + return 0; > + > + set_kernel_text_rw(); > + return 0; > +} > + > +int ftrace_arch_modify_post_process(void) > +{ > + /* at boot up, we are still writable */ > + if (system_state != SYSTEM_RUNNING) > + return 0; > + > + set_kernel_text_ro(); > + return 0; > +}
It would be prudent to avoid using system_state. People can change the point at which it transitions and can unexpectedly insert (or move) code to sites where system_state has new values, etc. It was a bad idea.
It would be clearer and more robust to create your own little flag for this purpose and set to it true and false at the places where that is appropriate for this application. It's just one more byte...
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