diff mbox series

[7/7] block, drivers: make lots of attribute_group globals const

Message ID 20231009165741.746184-7-max.kellermann@ionos.com
State New
Headers
Series [1/7] drivers/rtc/sysfs: move code to count_attribute_groups() |

Commit Message

Max Kellermann Oct. 9, 2023, 4:57 p.m. UTC 
  This moves those variables to the ".rodata" section which reduces the
kernel size a bit and protects the variables by putting them on
read-only pages at runtime.

Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
---
 block/blk-sysfs.c                   | 6 +++---
 block/genhd.c                       | 4 ++--
 block/partitions/core.c             | 2 +-
 drivers/base/cacheinfo.c            | 2 +-
 drivers/block/loop.c                | 2 +-
 drivers/block/rbd.c                 | 4 ++--
 drivers/input/input.c               | 2 +-
 drivers/input/serio/serio.c         | 2 +-
 drivers/pci/pci-sysfs.c             | 8 ++++----
 drivers/pci/pci.h                   | 6 +++---
 drivers/pps/sysfs.c                 | 2 +-
 drivers/rtc/sysfs.c                 | 2 +-
 drivers/tty/serial/8250/8250_port.c | 2 +-
 fs/ocfs2/cluster/sys.c              | 2 +-
 include/linux/khugepaged.h          | 2 +-
 include/linux/pps_kernel.h          | 2 +-
 mm/khugepaged.c                     | 2 +-
 17 files changed, 26 insertions(+), 26 deletions(-)

Comments

Greg KH Oct. 9, 2023, 5:30 p.m. UTC | #1 
On Mon, Oct 09, 2023 at 06:57:40PM +0200, Max Kellermann wrote:
> This moves those variables to the ".rodata" section which reduces the
> kernel size a bit and protects the variables by putting them on
> read-only pages at runtime.

The kernel size should still be the same overall, you are just moving
pointers from one section to another, right?

If not, what are the numbers, show them please.

But step back, are you SURE you can make these attribute group pointers
const?  They are modified by some subsystems by adding or removing items
from the lists, so why does the core need to change for that?

thanks,

greg k-h
Max Kellermann Oct. 9, 2023, 5:40 p.m. UTC | #2 
On Mon, Oct 9, 2023 at 7:30 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Oct 09, 2023 at 06:57:40PM +0200, Max Kellermann wrote:
> > This moves those variables to the ".rodata" section which reduces the
> > kernel size a bit and protects the variables by putting them on
> > read-only pages at runtime.
>
> The kernel size should still be the same overall, you are just moving
> pointers from one section to another, right?
>
> If not, what are the numbers, show them please.

Before this patch series:

   text       data        bss        dec        hex    filename
10645342    6836166    12476420    29957928    1c91f28    vmlinux

After:

   text       data        bss        dec        hex    filename
10645342    6835398    12476420    29957160    1c91c28    vmlinux

(Config attached if you wish to reproduce. I'm using stock GCC from
Debian Bookworm.)

It's only a few hundred bytes, and I havn't really dug deep enough to
explain to you why this is - my goal was (semantic) const-correctness
and .rodata protection, but those numbers are a side effect that
exists.


> But step back, are you SURE you can make these attribute group pointers
> const?  They are modified by some subsystems by adding or removing items
> from the lists, so why does the core need to change for that?

Some few do modify them, but they do not modify those pointers; they
allocate a new one (the 3 I sbumitted a patch for) or they modify
global variables (arch/pmu) which I'm not going to make "const". But
most globals can indeed be made "const".
diff mbox series

Patch

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 63e481262336..feea5d68b5a1 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -699,12 +699,12 @@  static umode_t blk_mq_queue_attr_visible(struct kobject *kobj,
 	return attr->mode;
 }
 
-static struct attribute_group queue_attr_group = {
+static const struct attribute_group queue_attr_group = {
 	.attrs = queue_attrs,
 	.is_visible = queue_attr_visible,
 };
 
-static struct attribute_group blk_mq_queue_attr_group = {
+static const struct attribute_group blk_mq_queue_attr_group = {
 	.attrs = blk_mq_queue_attrs,
 	.is_visible = blk_mq_queue_attr_visible,
 };
@@ -750,7 +750,7 @@  static const struct sysfs_ops queue_sysfs_ops = {
 	.store	= queue_attr_store,
 };
 
-static const struct attribute_group *blk_queue_attr_groups[] = {
+static const struct attribute_group *const blk_queue_attr_groups[] = {
 	&queue_attr_group,
 	&blk_mq_queue_attr_group,
 	NULL
diff --git a/block/genhd.c b/block/genhd.c
index d82560a79b04..9fa16e5de6d2 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1115,12 +1115,12 @@  static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
 	return a->mode;
 }
 
-static struct attribute_group disk_attr_group = {
+static const struct attribute_group disk_attr_group = {
 	.attrs = disk_attrs,
 	.is_visible = disk_visible,
 };
 
-static const struct attribute_group *disk_attr_groups[] = {
+static const struct attribute_group *const disk_attr_groups[] = {
 	&disk_attr_group,
 #ifdef CONFIG_BLK_DEV_IO_TRACE
 	&blk_trace_attr_group,
diff --git a/block/partitions/core.c b/block/partitions/core.c
index e137a87f4db0..463298e26757 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -232,7 +232,7 @@  static const struct attribute_group part_attr_group = {
 	.attrs = part_attrs,
 };
 
-static const struct attribute_group *part_attr_groups[] = {
+static const struct attribute_group *const part_attr_groups[] = {
 	&part_attr_group,
 #ifdef CONFIG_BLK_DEV_IO_TRACE
 	&blk_trace_attr_group,
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index b91c31c2a393..3642eed8ef74 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -786,7 +786,7 @@  static const struct attribute_group cache_default_group = {
 	.is_visible = cache_default_attrs_is_visible,
 };
 
-static const struct attribute_group *cache_default_groups[] = {
+static const struct attribute_group *const cache_default_groups[] = {
 	&cache_default_group,
 	NULL,
 };
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 9f2d412fc560..c1718b17b5ef 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -736,7 +736,7 @@  static struct attribute *loop_attrs[] = {
 	NULL,
 };
 
-static struct attribute_group loop_attribute_group = {
+static const struct attribute_group loop_attribute_group = {
 	.name = "loop",
 	.attrs= loop_attrs,
 };
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index a999b698b131..73e616453c34 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -5246,11 +5246,11 @@  static struct attribute *rbd_attrs[] = {
 	NULL
 };
 
-static struct attribute_group rbd_attr_group = {
+static const struct attribute_group rbd_attr_group = {
 	.attrs = rbd_attrs,
 };
 
-static const struct attribute_group *rbd_attr_groups[] = {
+static const struct attribute_group *const rbd_attr_groups[] = {
 	&rbd_attr_group,
 	NULL
 };
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 8c5fdb0f858a..d97126d54947 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1597,7 +1597,7 @@  static const struct attribute_group input_dev_caps_attr_group = {
 	.attrs	= input_dev_caps_attrs,
 };
 
-static const struct attribute_group *input_dev_attr_groups[] = {
+static const struct attribute_group *const input_dev_attr_groups[] = {
 	&input_dev_attr_group,
 	&input_dev_id_attr_group,
 	&input_dev_caps_attr_group,
diff --git a/drivers/input/serio/serio.c b/drivers/input/serio/serio.c
index 767fc9efb4a8..ef82d20572b0 100644
--- a/drivers/input/serio/serio.c
+++ b/drivers/input/serio/serio.c
@@ -474,7 +474,7 @@  static const struct attribute_group serio_device_attr_group = {
 	.attrs	= serio_device_attrs,
 };
 
-static const struct attribute_group *serio_device_attr_groups[] = {
+static const struct attribute_group *const serio_device_attr_groups[] = {
 	&serio_id_attr_group,
 	&serio_device_attr_group,
 	NULL
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d9eede2dbc0e..f2147da6e4a5 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -455,7 +455,7 @@  static const struct attribute_group pci_bus_group = {
 	.attrs = pci_bus_attrs,
 };
 
-const struct attribute_group *pci_bus_groups[] = {
+const struct attribute_group *const pci_bus_groups[] = {
 	&pci_bus_group,
 	NULL,
 };
@@ -647,7 +647,7 @@  static const struct attribute_group pcibus_group = {
 	.attrs = pcibus_attrs,
 };
 
-const struct attribute_group *pcibus_groups[] = {
+const struct attribute_group *const pcibus_groups[] = {
 	&pcibus_group,
 	NULL,
 };
@@ -1604,7 +1604,7 @@  static const struct attribute_group pci_dev_group = {
 	.attrs = pci_dev_attrs,
 };
 
-const struct attribute_group *pci_dev_groups[] = {
+const struct attribute_group *const pci_dev_groups[] = {
 	&pci_dev_group,
 	&pci_dev_config_attr_group,
 	&pci_dev_rom_attr_group,
@@ -1641,7 +1641,7 @@  static const struct attribute_group pcie_dev_attr_group = {
 	.is_visible = pcie_dev_attrs_are_visible,
 };
 
-static const struct attribute_group *pci_dev_attr_groups[] = {
+static const struct attribute_group *const pci_dev_attr_groups[] = {
 	&pci_dev_attr_group,
 	&pci_dev_hp_attr_group,
 #ifdef CONFIG_PCI_IOV
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 39a8932dc340..046d6c9944cd 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -182,10 +182,10 @@  static inline int pci_no_d1d2(struct pci_dev *dev)
 	return (dev->no_d1d2 || parent_dstates);
 
 }
-extern const struct attribute_group *pci_dev_groups[];
-extern const struct attribute_group *pcibus_groups[];
+extern const struct attribute_group *const pci_dev_groups[];
+extern const struct attribute_group *const pcibus_groups[];
 extern const struct device_type pci_dev_type;
-extern const struct attribute_group *pci_bus_groups[];
+extern const struct attribute_group *const pci_bus_groups[];
 
 extern unsigned long pci_hotplug_io_size;
 extern unsigned long pci_hotplug_mmio_size;
diff --git a/drivers/pps/sysfs.c b/drivers/pps/sysfs.c
index 134bc33f6ad0..355ce20b6e53 100644
--- a/drivers/pps/sysfs.c
+++ b/drivers/pps/sysfs.c
@@ -93,7 +93,7 @@  static const struct attribute_group pps_group = {
 	.attrs = pps_attrs,
 };
 
-const struct attribute_group *pps_groups[] = {
+const struct attribute_group *const pps_groups[] = {
 	&pps_group,
 	NULL,
 };
diff --git a/drivers/rtc/sysfs.c b/drivers/rtc/sysfs.c
index 9c45c2557e28..c126cb706b27 100644
--- a/drivers/rtc/sysfs.c
+++ b/drivers/rtc/sysfs.c
@@ -303,7 +303,7 @@  static struct attribute_group rtc_attr_group = {
 	.attrs		= rtc_attrs,
 };
 
-static const struct attribute_group *rtc_attr_groups[] = {
+static const struct attribute_group *const rtc_attr_groups[] = {
 	&rtc_attr_group,
 	NULL
 };
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 141627370aab..7af8f196e00f 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -3187,7 +3187,7 @@  static struct attribute *serial8250_dev_attrs[] = {
 	NULL
 };
 
-static struct attribute_group serial8250_dev_attr_group = {
+static const struct attribute_group serial8250_dev_attr_group = {
 	.attrs = serial8250_dev_attrs,
 };
 
diff --git a/fs/ocfs2/cluster/sys.c b/fs/ocfs2/cluster/sys.c
index 022f716c74ff..63e14ef53610 100644
--- a/fs/ocfs2/cluster/sys.c
+++ b/fs/ocfs2/cluster/sys.c
@@ -31,7 +31,7 @@  static struct attribute *o2cb_attrs[] = {
 	NULL,
 };
 
-static struct attribute_group o2cb_attr_group = {
+static const struct attribute_group o2cb_attr_group = {
 	.attrs = o2cb_attrs,
 };
 
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
index f68865e19b0b..85b442e9e638 100644
--- a/include/linux/khugepaged.h
+++ b/include/linux/khugepaged.h
@@ -5,7 +5,7 @@ 
 #include <linux/sched/coredump.h> /* MMF_VM_HUGEPAGE */
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-extern struct attribute_group khugepaged_attr_group;
+extern const struct attribute_group khugepaged_attr_group;
 
 extern int khugepaged_init(void);
 extern void khugepaged_destroy(void);
diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 78c8ac4951b5..996db99f983f 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -66,7 +66,7 @@  struct pps_device {
  * Global variables
  */
 
-extern const struct attribute_group *pps_groups[];
+extern const struct attribute_group *const pps_groups[];
 
 /*
  * Internal functions.
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 88433cc25d8a..cd1b26075d1b 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -339,7 +339,7 @@  static struct attribute *khugepaged_attr[] = {
 	NULL,
 };
 
-struct attribute_group khugepaged_attr_group = {
+const struct attribute_group khugepaged_attr_group = {
 	.attrs = khugepaged_attr,
 	.name = "khugepaged",
 };