Messages in this thread | | | From | Rasmus Villemoes <> | Subject | Re: [PATCH] x86, mtrr: mark range_new in mtrr_calc_range_state() as __initdata | Date | Tue, 01 Dec 2015 12:58:42 +0100 |
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On Fri, Nov 27 2015, Ingo Molnar <mingo@kernel.org> wrote:
> * Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > >> range_new doesn't seem to be used after init. It is only passed to >> memset, sum_ranges, memcmp and x86_get_mtrr_mem_range, the latter of >> which also only passes it on to various *range* library functions. So >> mark it __initdata to free up an extra page after init. >> >> nr_range_new is unconditionally assigned to before it is read, so >> there's no point in having it static. >> >> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> >> --- >> arch/x86/kernel/cpu/mtrr/cleanup.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c >> index 70d7c93f4550..b1a9ad366f67 100644 >> --- a/arch/x86/kernel/cpu/mtrr/cleanup.c >> +++ b/arch/x86/kernel/cpu/mtrr/cleanup.c >> @@ -593,9 +593,9 @@ mtrr_calc_range_state(u64 chunk_size, u64 gran_size, >> unsigned long x_remove_base, >> unsigned long x_remove_size, int i) >> { >> - static struct range range_new[RANGE_NUM]; >> + static struct range range_new[RANGE_NUM] __initdata; >> unsigned long range_sums_new; >> - static int nr_range_new; >> + int nr_range_new; >> int num_reg; >> >> /* Convert ranges to var ranges state: */ > > So this static variable actually surprised me - I never realized it was there - > and it's not some simple 'once' flag, but something that is essential semantics. > > So marking it __initdata is correct, but please also move it out of function local > variables scope, into file scope - and name it properly as well, like > mtrr_new_range[] or so?
I can certainly do that, but isn't the usual preference to keep the scope as small as possible? IOW, why do you want to make this a file-scoped variable?
Also, I don't really see how the 'static' has 'essential semantics'. AFAICT, the contents are wiped on every invocation of mtrr_calc_range_state, so the only reason it's static is to avoid blowing the stack.
Rasmus
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