diff mbox

ARM: tegra: paz00: fix __initdata placement

Message ID 20170123074347.GA29804@dtor-ws (mailing list archive)
State New, archived
Headers show

Commit Message

Dmitry Torokhov Jan. 23, 2017, 7:43 a.m. UTC
To have expected effect the __initdata attribute should go after variable
name and before initializer.`

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 arch/arm/mach-tegra/board-paz00.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Marc Dietrich Jan. 23, 2017, 10:04 a.m. UTC | #1
Hello Dmitry,

Am Sonntag, 22. Januar 2017, 23:43:47 CET schrieb Dmitry Torokhov:
> To have expected effect the __initdata attribute should go after variable
> name and before initializer.`
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  arch/arm/mach-tegra/board-paz00.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mach-tegra/board-paz00.c
> b/arch/arm/mach-tegra/board-paz00.c index 7478f6fb3664..ea6bff404161 100644
> --- a/arch/arm/mach-tegra/board-paz00.c
> +++ b/arch/arm/mach-tegra/board-paz00.c
> @@ -23,7 +23,7 @@
> 
>  #include "board.h"
> 
> -static struct property_entry __initdata wifi_rfkill_prop[] = {
> +static struct property_entry wifi_rfkill_prop[] __initdata = {
>  	PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
>  	PROPERTY_ENTRY_STRING("type", "wlan"),
>  	{ },

you are right according to the documentation, but objdump -s always shows that 
it gets put into the .rodata section. So this patch has no effect, because 
result is always same (and wrong). It's also possible that I'm doing something 
wrong :-) Btw, there are hundreds of such __initdata misplacement in the 
kernel.

Marc
Thierry Reding Jan. 23, 2017, 4:24 p.m. UTC | #2
On Mon, Jan 23, 2017 at 11:04:22AM +0100, Marc Dietrich wrote:
> Hello Dmitry,
> 
> Am Sonntag, 22. Januar 2017, 23:43:47 CET schrieb Dmitry Torokhov:
> > To have expected effect the __initdata attribute should go after variable
> > name and before initializer.`
> > 
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > ---
> >  arch/arm/mach-tegra/board-paz00.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm/mach-tegra/board-paz00.c
> > b/arch/arm/mach-tegra/board-paz00.c index 7478f6fb3664..ea6bff404161 100644
> > --- a/arch/arm/mach-tegra/board-paz00.c
> > +++ b/arch/arm/mach-tegra/board-paz00.c
> > @@ -23,7 +23,7 @@
> > 
> >  #include "board.h"
> > 
> > -static struct property_entry __initdata wifi_rfkill_prop[] = {
> > +static struct property_entry wifi_rfkill_prop[] __initdata = {
> >  	PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
> >  	PROPERTY_ENTRY_STRING("type", "wlan"),
> >  	{ },
> 
> you are right according to the documentation, but objdump -s always shows that 
> it gets put into the .rodata section. So this patch has no effect, because 
> result is always same (and wrong). It's also possible that I'm doing something 
> wrong :-) Btw, there are hundreds of such __initdata misplacement in the 
> kernel.

Hmm... I get this:

	$ objdump -t build/tegra20/arch/arm/mach-tegra/board-paz00.o

	build/tegra20/arch/arm/mach-tegra/board-paz00.o:     file format
	elf32-little

	SYMBOL TABLE:
	00000000 l    df *ABS*  00000000 board-paz00.c
	00000000 l    d  .text  00000000 .text
	00000000 l    d  .data  00000000 .data
	00000000 l    d  .bss   00000000 .bss
	00000000 l    d  .init.text     00000000 .init.text
	00000000 l       .init.text     00000000 $a
	00000000 l       .data  00000000 .LANCHOR1
	00000000 l       .init.data     00000000 .LANCHOR0
	00000000 l    d  .ARM.extab.init.text   00000000 .ARM.extab.init.text
	00000000 l    d  .ARM.exidx.init.text   00000000 .ARM.exidx.init.text
	00000000 l       .ARM.exidx.init.text   00000000 $d
	00000000 l       .data  00000000 $d
	00000000 l     O .data  000001c8 wifi_rfkill_device
	000001c8 l     O .data  00000048 wifi_gpio_lookup
	00000000 l    d  .rodata.str1.4 00000000 .rodata.str1.4
	00000000 l       .rodata.str1.4 00000000 $d
	00000000 l    d  .init.data     00000000 .init.data
	00000000 l       .init.data     00000000 $d
	00000000 l     O .init.data     00000048 wifi_rfkill_prop
	00000000 l    d  .debug_frame   00000000 .debug_frame
	00000010 l       .debug_frame   00000000 $d
	00000000 l    d  .debug_info    00000000 .debug_info
	00000000 l    d  .debug_abbrev  00000000 .debug_abbrev
	00000000 l    d  .debug_aranges 00000000 .debug_aranges
	00000000 l    d  .debug_ranges  00000000 .debug_ranges
	00000000 l    d  .debug_line    00000000 .debug_line
	00000000 l    d  .debug_str     00000000 .debug_str
	00000000 l    d  .note.GNU-stack        00000000 .note.GNU-stack
	00000000 l    d  .comment       00000000 .comment
	00000000 l    d  .ARM.attributes        00000000 .ARM.attributes
	00000000 g     F .init.text     00000030 tegra_paz00_wifikill_init
	00000000         *UND*  00000000 platform_device_add_properties
	00000000         *UND*  00000000 gpiod_add_lookup_table
	00000000         *UND*  00000000 platform_device_register
	00000000         *UND*  00000000 __aeabi_unwind_cpp_pr0

So it correctly ends up in .init.data for me. And it does so with or
without the patch. GCCs documentation doesn't seem to say where exactly
these attributes need to be put, though the examples given all have the
attribute right before the =.

Oh... interestingly checkpatch does seem to have a check for this now,
and it does recommend that __initdata be placed after wifi_rfkill_prop,
so I'm going to apply this.

Thierry
Marc Dietrich Jan. 24, 2017, 9:08 a.m. UTC | #3
Hello Thierry,

Am Montag, 23. Januar 2017, 17:24:28 CET schrieb Thierry Reding:
> On Mon, Jan 23, 2017 at 11:04:22AM +0100, Marc Dietrich wrote:
> > Hello Dmitry,
> > 
> > Am Sonntag, 22. Januar 2017, 23:43:47 CET schrieb Dmitry Torokhov:
> > > To have expected effect the __initdata attribute should go after
> > > variable
> > > name and before initializer.`
> > > 
> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > > ---
> > > 
> > >  arch/arm/mach-tegra/board-paz00.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm/mach-tegra/board-paz00.c
> > > b/arch/arm/mach-tegra/board-paz00.c index 7478f6fb3664..ea6bff404161
> > > 100644
> > > --- a/arch/arm/mach-tegra/board-paz00.c
> > > +++ b/arch/arm/mach-tegra/board-paz00.c
> > > @@ -23,7 +23,7 @@
> > > 
> > >  #include "board.h"
> > > 
> > > -static struct property_entry __initdata wifi_rfkill_prop[] = {
> > > +static struct property_entry wifi_rfkill_prop[] __initdata = {
> > > 
> > >  	PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
> > >  	PROPERTY_ENTRY_STRING("type", "wlan"),
> > >  	{ },
> > 
> > you are right according to the documentation, but objdump -s always shows
> > that it gets put into the .rodata section. So this patch has no effect,
> > because result is always same (and wrong). It's also possible that I'm
> > doing something wrong :-) Btw, there are hundreds of such __initdata
> > misplacement in the kernel.
> 
> Hmm... I get this:
> 
> 	$ objdump -t build/tegra20/arch/arm/mach-tegra/board-paz00.o
> 
> 	build/tegra20/arch/arm/mach-tegra/board-paz00.o:     file format
> 	elf32-little
> 
> 	SYMBOL TABLE:
> 	00000000 l    df *ABS*  00000000 board-paz00.c
> 	00000000 l    d  .text  00000000 .text
> 	00000000 l    d  .data  00000000 .data
> 	00000000 l    d  .bss   00000000 .bss
> 	00000000 l    d  .init.text     00000000 .init.text
> 	00000000 l       .init.text     00000000 $a
> 	00000000 l       .data  00000000 .LANCHOR1
> 	00000000 l       .init.data     00000000 .LANCHOR0
> 	00000000 l    d  .ARM.extab.init.text   00000000 .ARM.extab.init.text
> 	00000000 l    d  .ARM.exidx.init.text   00000000 .ARM.exidx.init.text
> 	00000000 l       .ARM.exidx.init.text   00000000 $d
> 	00000000 l       .data  00000000 $d
> 	00000000 l     O .data  000001c8 wifi_rfkill_device
> 	000001c8 l     O .data  00000048 wifi_gpio_lookup
> 	00000000 l    d  .rodata.str1.4 00000000 .rodata.str1.4
> 	00000000 l       .rodata.str1.4 00000000 $d
> 	00000000 l    d  .init.data     00000000 .init.data
> 	00000000 l       .init.data     00000000 $d
> 	00000000 l     O .init.data     00000048 wifi_rfkill_prop
> 	00000000 l    d  .debug_frame   00000000 .debug_frame
> 	00000010 l       .debug_frame   00000000 $d
> 	00000000 l    d  .debug_info    00000000 .debug_info
> 	00000000 l    d  .debug_abbrev  00000000 .debug_abbrev
> 	00000000 l    d  .debug_aranges 00000000 .debug_aranges
> 	00000000 l    d  .debug_ranges  00000000 .debug_ranges
> 	00000000 l    d  .debug_line    00000000 .debug_line
> 	00000000 l    d  .debug_str     00000000 .debug_str
> 	00000000 l    d  .note.GNU-stack        00000000 .note.GNU-stack
> 	00000000 l    d  .comment       00000000 .comment
> 	00000000 l    d  .ARM.attributes        00000000 .ARM.attributes
> 	00000000 g     F .init.text     00000030 tegra_paz00_wifikill_init
> 	00000000         *UND*  00000000 platform_device_add_properties
> 	00000000         *UND*  00000000 gpiod_add_lookup_table
> 	00000000         *UND*  00000000 platform_device_register
> 	00000000         *UND*  00000000 __aeabi_unwind_cpp_pr0
> 
> So it correctly ends up in .init.data for me. And it does so with or
> without the patch. GCCs documentation doesn't seem to say where exactly
> these attributes need to be put, though the examples given all have the
> attribute right before the =.

ok, objdump -s is maybe not appropriate to display such things.

Contents of section .init.data:
 0000 2c000000 0c000000 00010000 00000000  ,...............
 0010 34000000 00000000 40000000 05000000  4.......@.......
 0020 00010000 00000000 48000000 00000000  ........H.......
 0030 00000000 00000000 00000000 00000000  ................
 0040 00000000 00000000                    ........        
Contents of section .rodata.str1.4:
 0000 72666b69 6c6c5f67 70696f00 74656772  rfkill_gpio.tegr
 0010 612d6770 696f0000 72657365 74000000  a-gpio..reset...
 0020 73687574 646f776e 00000000 6e616d65  shutdown....name
 0030 00000000 77696669 5f72666b 696c6c00  ....wifi_rfkill.
 0040 74797065 00000000 776c616e 00        type....wlan.   

In fact, .init.data seems to contain relocations to .rodata.str1.4, which "-s" 
does not resolve.
 
> Oh... interestingly checkpatch does seem to have a check for this now,
> and it does recommend that __initdata be placed after wifi_rfkill_prop,
> so I'm going to apply this.

Btw, where is your tree for 4.11? git.kernel.org shows no action since 
November. Please also include https://patchwork.ozlabs.org/patch/704367/ if 
you haven't done yet. I forgot to add a #stable tag for 4.9 and 4.10.

Marc
Dmitry Torokhov Jan. 24, 2017, 6:27 p.m. UTC | #4
On Mon, Jan 23, 2017 at 05:24:28PM +0100, Thierry Reding wrote:
> On Mon, Jan 23, 2017 at 11:04:22AM +0100, Marc Dietrich wrote:
> > Hello Dmitry,
> > 
> > Am Sonntag, 22. Januar 2017, 23:43:47 CET schrieb Dmitry Torokhov:
> > > To have expected effect the __initdata attribute should go after variable
> > > name and before initializer.`
> > > 
> > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > > ---
> > >  arch/arm/mach-tegra/board-paz00.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/arch/arm/mach-tegra/board-paz00.c
> > > b/arch/arm/mach-tegra/board-paz00.c index 7478f6fb3664..ea6bff404161 100644
> > > --- a/arch/arm/mach-tegra/board-paz00.c
> > > +++ b/arch/arm/mach-tegra/board-paz00.c
> > > @@ -23,7 +23,7 @@
> > > 
> > >  #include "board.h"
> > > 
> > > -static struct property_entry __initdata wifi_rfkill_prop[] = {
> > > +static struct property_entry wifi_rfkill_prop[] __initdata = {
> > >  	PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
> > >  	PROPERTY_ENTRY_STRING("type", "wlan"),
> > >  	{ },
> > 
> > you are right according to the documentation, but objdump -s always shows that 
> > it gets put into the .rodata section. So this patch has no effect, because 
> > result is always same (and wrong). It's also possible that I'm doing something 
> > wrong :-) Btw, there are hundreds of such __initdata misplacement in the 
> > kernel.
> 
> Hmm... I get this:
> 
> 	$ objdump -t build/tegra20/arch/arm/mach-tegra/board-paz00.o
> 
> 	build/tegra20/arch/arm/mach-tegra/board-paz00.o:     file format
> 	elf32-little
> 
> 	SYMBOL TABLE:
> 	00000000 l    df *ABS*  00000000 board-paz00.c
> 	00000000 l    d  .text  00000000 .text
> 	00000000 l    d  .data  00000000 .data
> 	00000000 l    d  .bss   00000000 .bss
> 	00000000 l    d  .init.text     00000000 .init.text
> 	00000000 l       .init.text     00000000 $a
> 	00000000 l       .data  00000000 .LANCHOR1
> 	00000000 l       .init.data     00000000 .LANCHOR0
> 	00000000 l    d  .ARM.extab.init.text   00000000 .ARM.extab.init.text
> 	00000000 l    d  .ARM.exidx.init.text   00000000 .ARM.exidx.init.text
> 	00000000 l       .ARM.exidx.init.text   00000000 $d
> 	00000000 l       .data  00000000 $d
> 	00000000 l     O .data  000001c8 wifi_rfkill_device
> 	000001c8 l     O .data  00000048 wifi_gpio_lookup
> 	00000000 l    d  .rodata.str1.4 00000000 .rodata.str1.4
> 	00000000 l       .rodata.str1.4 00000000 $d
> 	00000000 l    d  .init.data     00000000 .init.data
> 	00000000 l       .init.data     00000000 $d
> 	00000000 l     O .init.data     00000048 wifi_rfkill_prop
> 	00000000 l    d  .debug_frame   00000000 .debug_frame
> 	00000010 l       .debug_frame   00000000 $d
> 	00000000 l    d  .debug_info    00000000 .debug_info
> 	00000000 l    d  .debug_abbrev  00000000 .debug_abbrev
> 	00000000 l    d  .debug_aranges 00000000 .debug_aranges
> 	00000000 l    d  .debug_ranges  00000000 .debug_ranges
> 	00000000 l    d  .debug_line    00000000 .debug_line
> 	00000000 l    d  .debug_str     00000000 .debug_str
> 	00000000 l    d  .note.GNU-stack        00000000 .note.GNU-stack
> 	00000000 l    d  .comment       00000000 .comment
> 	00000000 l    d  .ARM.attributes        00000000 .ARM.attributes
> 	00000000 g     F .init.text     00000030 tegra_paz00_wifikill_init
> 	00000000         *UND*  00000000 platform_device_add_properties
> 	00000000         *UND*  00000000 gpiod_add_lookup_table
> 	00000000         *UND*  00000000 platform_device_register
> 	00000000         *UND*  00000000 __aeabi_unwind_cpp_pr0
> 
> So it correctly ends up in .init.data for me. And it does so with or
> without the patch. GCCs documentation doesn't seem to say where exactly
> these attributes need to be put, though the examples given all have the
> attribute right before the =.
> 
> Oh... interestingly checkpatch does seem to have a check for this now,
> and it does recommend that __initdata be placed after wifi_rfkill_prop,
> so I'm going to apply this.

Ah, so I mis-remembered the rules and it seems that it does not really
matter if __initdata goes before or after variable name, it can't go
between "struct" and its name. From that checkpatch change introducing
the check:

    static struct __initdata samsung_pll_clock exynos4_plls[nr_plls] = { 

    does NOT put exynos4_plls in the .initdata section.  The __initdata marker
    can be virtually anywhere on the line, EXCEPT right after "struct".  The
    preferred location is before the "=" sign if there is one, or before the
    trailing ";" otherwise.

so if you are applying it you might want to change the wording as to the
effect of "making checkpatch happy" which wasn't my intention, but was
the outcome ;)

Thanks.
Thierry Reding Jan. 25, 2017, 8:11 a.m. UTC | #5
On Sun, Jan 22, 2017 at 11:43:47PM -0800, Dmitry Torokhov wrote:
> To have expected effect the __initdata attribute should go after variable
> name and before initializer.`
> 
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  arch/arm/mach-tegra/board-paz00.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied with an updated commit message.

Thanks,
Thierry
diff mbox

Patch

diff --git a/arch/arm/mach-tegra/board-paz00.c b/arch/arm/mach-tegra/board-paz00.c
index 7478f6fb3664..ea6bff404161 100644
--- a/arch/arm/mach-tegra/board-paz00.c
+++ b/arch/arm/mach-tegra/board-paz00.c
@@ -23,7 +23,7 @@ 
 
 #include "board.h"
 
-static struct property_entry __initdata wifi_rfkill_prop[] = {
+static struct property_entry wifi_rfkill_prop[] __initdata = {
 	PROPERTY_ENTRY_STRING("name", "wifi_rfkill"),
 	PROPERTY_ENTRY_STRING("type", "wlan"),
 	{ },