linux-kernel - [PATCH] vme: bridges: reduce stack usage

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Message-Id: <20200107200610.3482901-1-arnd@arndb.de>
Date:   Tue,  7 Jan 2020 21:05:43 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Martyn Welch <martyn@...chs.me.uk>,
        Manohar Vanga <manohar.vanga@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Oleksandr Natalenko <oleksandr@...hat.com>,
        Arnd Bergmann <arnd@...db.de>, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] vme: bridges: reduce stack usage

With CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3, the stack usage in vme_fake
grows above the warning limit:

drivers/vme/bridges/vme_fake.c: In function 'fake_master_read':
drivers/vme/bridges/vme_fake.c:610:1: error: the frame size of 1160 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
drivers/vme/bridges/vme_fake.c: In function 'fake_master_write':
drivers/vme/bridges/vme_fake.c:797:1: error: the frame size of 1160 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

The problem is that in some configurations, each call to
fake_vmereadX() puts another variable on the stack.

Reduce the amount of inlining to get back to the previous state,
with no function using more than 200 bytes each.

Fixes: mmtom ("init/Kconfig: enable -O3 for all arches")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/vme/bridges/vme_fake.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/vme/bridges/vme_fake.c b/drivers/vme/bridges/vme_fake.c
index 3208a4409e44..6a1bc284f297 100644
--- a/drivers/vme/bridges/vme_fake.c
+++ b/drivers/vme/bridges/vme_fake.c
@@ -414,8 +414,9 @@ static void fake_lm_check(struct fake_driver *bridge, unsigned long long addr,
 	}
 }
 
-static u8 fake_vmeread8(struct fake_driver *bridge, unsigned long long addr,
-		u32 aspace, u32 cycle)
+static noinline_for_stack u8 fake_vmeread8(struct fake_driver *bridge,
+					   unsigned long long addr,
+					   u32 aspace, u32 cycle)
 {
 	u8 retval = 0xff;
 	int i;
@@ -446,8 +447,9 @@ static u8 fake_vmeread8(struct fake_driver *bridge, unsigned long long addr,
 	return retval;
 }
 
-static u16 fake_vmeread16(struct fake_driver *bridge, unsigned long long addr,
-		u32 aspace, u32 cycle)
+static noinline_for_stack u16 fake_vmeread16(struct fake_driver *bridge,
+					     unsigned long long addr,
+					     u32 aspace, u32 cycle)
 {
 	u16 retval = 0xffff;
 	int i;
@@ -478,8 +480,9 @@ static u16 fake_vmeread16(struct fake_driver *bridge, unsigned long long addr,
 	return retval;
 }
 
-static u32 fake_vmeread32(struct fake_driver *bridge, unsigned long long addr,
-		u32 aspace, u32 cycle)
+static noinline_for_stack u32 fake_vmeread32(struct fake_driver *bridge,
+					     unsigned long long addr,
+					     u32 aspace, u32 cycle)
 {
 	u32 retval = 0xffffffff;
 	int i;
@@ -609,8 +612,9 @@ static ssize_t fake_master_read(struct vme_master_resource *image, void *buf,
 	return retval;
 }
 
-static void fake_vmewrite8(struct fake_driver *bridge, u8 *buf,
-			   unsigned long long addr, u32 aspace, u32 cycle)
+static noinline_for_stack void fake_vmewrite8(struct fake_driver *bridge,
+					      u8 *buf, unsigned long long addr,
+					      u32 aspace, u32 cycle)
 {
 	int i;
 	unsigned long long start, end, offset;
@@ -639,8 +643,9 @@ static void fake_vmewrite8(struct fake_driver *bridge, u8 *buf,
 
 }
 
-static void fake_vmewrite16(struct fake_driver *bridge, u16 *buf,
-			    unsigned long long addr, u32 aspace, u32 cycle)
+static noinline_for_stack void fake_vmewrite16(struct fake_driver *bridge,
+					       u16 *buf, unsigned long long addr,
+					       u32 aspace, u32 cycle)
 {
 	int i;
 	unsigned long long start, end, offset;
@@ -669,8 +674,9 @@ static void fake_vmewrite16(struct fake_driver *bridge, u16 *buf,
 
 }
 
-static void fake_vmewrite32(struct fake_driver *bridge, u32 *buf,
-			    unsigned long long addr, u32 aspace, u32 cycle)
+static noinline_for_stack void fake_vmewrite32(struct fake_driver *bridge,
+					       u32 *buf, unsigned long long addr,
+					       u32 aspace, u32 cycle)
 {
 	int i;
 	unsigned long long start, end, offset;
-- 
2.20.0