Commit-ID: c332813b51cbe807d539bb059b81235abf1e3fdd
Gitweb: http://git.kernel.org/tip/c332813b51cbe807d539bb059b81235abf1e3fdd
Author: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 1 Dec 2015 21:44:50 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 4 Dec 2015 09:11:28 +0100
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@xxxxxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Link: http://lkml.kernel.org/r/1449002691-20783-1-git-send-email-linux@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/cpu/mtrr/cleanup.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
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 @@ 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];
+ /*
+ * 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: */
--
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