Messages in this thread | | | Subject | Re: Jump Label initialization | From | Jan Glauber <> | Date | Thu, 29 Sep 2011 14:04:54 +0200 |
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On Wed, 2011-09-28 at 19:14 -0700, Jeremy Fitzhardinge wrote: > Hi all, > > I'm trying to use the jump label machinery as part of the pv ticketlock > work I'm doing on x86. > > The problem I'm having at the moment is that I do my spinlock setup in > smp_prepare_boot_cpu(), which happens before jump_label_init() gets > called, and so the latter goes and nops out all my enabled jump label key. > > I'm experimenting at the moment with a patch to allow > jump_label_enable() to be called fairly early, and have that be > respected by jump_label_init(). I'm doing this by replacing > arch_jump_label_poke_text_early() with > arch_jump_label_transform_early(), which shares most of its code with > its non-early variant, except that it expects to run in a pre-SMP > environment. > > Does this seem plausible? (I haven't tested it yet.) > > The x86, mips and sparc patches are fairly simple; I forgot to look at > powerpc, and I didn't fully investigate s390.
s390 does not have the early() variant since it didn't need it. On pre-SMP we probably don't need stop_machine() so creating arch_jump_label_transform_early() by leaving out stop_machine() and patching the code directly should be fine.
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