Messages in this thread |  | | Date | Sun, 20 Dec 2015 16:27:49 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 1/2] x86/msr: add on cpu read/modify/write function |
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On Sun, Dec 20, 2015 at 02:28:48PM +0100, Thomas Gleixner wrote: > So this is a copy of the above !SMP inline. What's wrong with providing: > > int rmwmsrl_safe(msr_no, clear_mask, set_mask) > > in x86/lib/msr.c and make the !SMP variant of rdmsrl_safe_on_cpu() and that > variant for the SMP case a simple wrapper around it? > > static void remote_rmwmsrl_safe(void *info) > { > struct msr_action *ma = info; > > return rmwmsrl_safe(ma->msr, ma->clear_mask, ma->set_mask); > } > > No gotos, no pointless code duplication. Just simple.
TBH, I find this new "rmwmsrl" interface (the name is unreadable, btw) silly:
It provides a plain read-modify-write on a MSR and nothing more but patch 2 immediately shows that this interface is insufficient for the other cases, i.e. package_power_limit_irq_save() for example, where you need to do something more like check bits or error handling.
So there we do smp_call_function_single() with a function which does the MSR accesses and whatever else is needed.
So why add the former interface in the first place?
Having driver-specific functions do whatever it is required and then using a single IPI to run them is much cleaner than adding that unfortunate function which doesn't really suffice.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
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