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authorLinus Torvalds <torvalds@linux-foundation.org>2010-08-05 12:59:05 -0600
committerRusty Russell <rusty@rustcorp.com.au>2010-08-05 12:59:06 +0930
commit44032e631691adf1f406843d5e54deb795973ff7 (patch)
treee9cb4f72974386a2b174bf6e21f41be9aece7a10
parent22e268ebecc549f1b1907f114cb44d6044bdee3c (diff)
downloadvexpress-lsk-44032e631691adf1f406843d5e54deb795973ff7.tar.gz
module: reduce stack usage for each_symbol()
And now that I'm looking at that call-chain (to see if it would make sense to use some other more specific lock - doesn't look like it: all the readers are using RCU and this is the only writer), I also give you this trivial one-liner. It changes each_symbol() to not put that constant array on the stack, resulting in changing movq $C.388.31095, %rsi #, tmp85 subq $376, %rsp #, movq %rdi, %rbx # fn, fn leaq -208(%rbp), %rdi #, tmp84 movq %rbx, %rdx # fn, rep movsl xorl %esi, %esi # leaq -208(%rbp), %rdi #, tmp87 movq %r12, %rcx # data, call each_symbol_in_section.clone.0 # into xorl %esi, %esi # subq $216, %rsp #, movq %rdi, %rbx # fn, fn movq $arr.31078, %rdi #, call each_symbol_in_section.clone.0 # which is not so much about being obviously shorter and simpler because we don't unnecessarily copy that constant array around onto the stack, but also about having a much smaller stack footprint (376 vs 216 bytes - see the update of 'rsp'). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--kernel/module.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/module.c b/kernel/module.c
index b536db804ca..79545bda358 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -227,7 +227,7 @@ bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
unsigned int symnum, void *data), void *data)
{
struct module *mod;
- const struct symsearch arr[] = {
+ static const struct symsearch arr[] = {
{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,
NOT_GPL_ONLY, false },
{ __start___ksymtab_gpl, __stop___ksymtab_gpl,