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    SubjectRe: [PATCH -v3 6/7] kexec jump: __ftrace_enabled_save/restore

    * Huang Ying <ying.huang@intel.com> wrote:

    > On Fri, 2008-08-15 at 14:49 +0200, Ingo Molnar wrote:
    > > * Huang Ying <ying.huang@intel.com> wrote:
    > >
    > > > +/* Ftrace disable/restore without lock. Some synchronization mechanism
    > > > + * must be used to prevent ftrace_enabled to be changed between
    > > > + * disable/restore. */
    > >
    > > use the proper comment style please:
    > >
    > > /*
    > > *
    > > */
    >
    > OK. I will change it.

    it's upstream already, please send a followup clean up patch.

    > > > +static inline int __ftrace_enabled_save(void)
    > > > +{
    > > > +#ifdef CONFIG_FTRACE
    > > > + int saved_ftrace_enabled = ftrace_enabled;
    > > > + ftrace_enabled = 0;
    > > > + return saved_ftrace_enabled;
    > > > +#else
    > > > + return 0;
    > > > +#endif
    > > > +}
    > > > +
    > > > +static inline void __ftrace_enabled_restore(int enabled)
    > > > +{
    > > > +#ifdef CONFIG_FTRACE
    > > > + ftrace_enabled = enabled;
    > > > +#endif
    > > > +}
    > >
    > > hm, what is this used for?
    > >
    > > also, instead of such an ugly inline, why not create a proper
    > > kernel/trace/* function for this. That would also give it access to all
    > > the proper locking mechanisms - instead of relying on some extral
    > > mechanism.
    >
    > This function is used for kexec jump in machine_kexec(). Where all
    > non-boot CPUs and IRQ are disabled, system is going to kexec, and it
    > is not allowed to schedule to other process in this circumstance, so a
    > non-lock version is needed. A locked version has been implemented by
    > Steven Rostedt, I think it can be used for other circumstance.

    ok, fair enough.

    Ingo


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