x86/mm/mtrr: Mark the 'range_new' static variable in mtrr_calc_range_state() as __initdata
'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.
Its contents are wiped at every call to mtrr_calc_range_state(),
so it being static is not about preserving state between calls,
but simply to avoid a 4k+ stack frame. While there, add a
comment explaining this and why it's safe.
We could also mark nr_range_new as __initdata, but since it's
just a single int and also doesn't carry state between calls (it
is unconditionally assigned to before it is read), we might as
well make it an ordinary automatic variable.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Link: http://lkml.kernel.org/r/1449002691-20783-1-git-send-email-linux@rasmusvillemoes.dk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c b/arch/x86/kernel/cpu/mtrr/cleanup.c
index 70d7c93..0d98503 100644
--- a/arch/x86/kernel/cpu/mtrr/cleanup.c
+++ b/arch/x86/kernel/cpu/mtrr/cleanup.c
@@ -593,9 +593,16 @@
unsigned long x_remove_base,
unsigned long x_remove_size, int i)
{
- static struct range range_new[RANGE_NUM];
+ /*
+ * range_new should really be an automatic variable, but
+ * putting 4096 bytes on the stack is frowned upon, to put it
+ * mildly. It is safe to make it a static __initdata variable,
+ * since mtrr_calc_range_state is only called during init and
+ * there's no way it will call itself recursively.
+ */
+ 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: */