[PATCH 00/22] various dynamic_debug patches

[PATCH 00/22] various dynamic_debug patches

[Rasmus Villemoes]

This started as an experiment to see how hard it would be to change
the four pointers in struct _ddebug into relative offsets, a la
CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
pr_debug site (and thus exactly making up for the extra space used by
the introduction of jump labels in 9049fc74). I stumbled on a few
things that are probably worth fixing regardless of whether the latter
half of this series is deemed worthwhile.

Patch relationships: 1-2, 3-4, 5-6 and 15-16 can be applied
individually, though 2, 4 and 6 probably makes most sense in the
context of the final goal of the series.

7-12 I believe make sense on their own. Patch 13 again only makes
sense if we go all the way, and 14 and 17 depend on 13.

18-21 are more preparatory patches, and finally 22 switch over x86-64
to use CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS. I've tested that the
end result boots under virtme and that the dynamic_debug control file
has the expected contents.

Rasmus Villemoes (22):
  linux/device.h: use DYNAMIC_DEBUG_BRANCH in dev_dbg_ratelimited
  linux/device.h: use unique identifier for each struct _ddebug
  linux/net.h: use DYNAMIC_DEBUG_BRANCH in net_dbg_ratelimited
  linux/net.h: use unique identifier for each struct _ddebug
  linux/printk.h: use DYNAMIC_DEBUG_BRANCH in pr_debug_ratelimited
  linux/printk.h: use unique identifier for each struct _ddebug
  dynamic_debug: consolidate DEFINE_DYNAMIC_DEBUG_METADATA definitions
  dynamic_debug: don't duplicate modname in ddebug_add_module
  dynamic_debug: use pointer comparison in ddebug_remove_module
  dynamic_debug: remove unused EXPORT_SYMBOLs
  dynamic_debug: move pr_err from module.c to ddebug_add_module
  dynamic_debug: add static inline stub for ddebug_add_module
  dynamic_debug: refactor dynamic_pr_debug and friends
  btrfs: implement btrfs_debug* in terms of helper macro
  ACPI: use proper DYNAMIC_DEBUG_BRANCH macro
  ACPI: remove unused __acpi_handle_debug macro
  ACPI: implement acpi_handle_debug in terms of _dynamic_func_call
  dynamic_debug: introduce accessors for string members of struct
    _ddebug
  dynamic_debug: drop use of bitfields in struct _ddebug
  dynamic_debug: introduce CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS
  x86: jump_label: introduce ASM_STATIC_KEY_INIT_{TRUE,FALSE}
  x86_64: use relative pointers with dynamic debug

 arch/x86/Kconfig                     |   1 +
 arch/x86/include/asm/dynamic_debug.h |  35 +++++++++
 arch/x86/include/asm/jump_label.h    |  18 +++++
 fs/btrfs/ctree.h                     |  34 +++------
 include/linux/acpi.h                 |  11 +--
 include/linux/device.h               |   6 +-
 include/linux/dynamic_debug.h        | 126 +++++++++++++++++++--------------
 include/linux/jump_label.h           |   2 +
 include/linux/net.h                  |   6 +-
 include/linux/printk.h               |   6 +-
 kernel/module.c                      |   6 +-
 lib/Kconfig.debug                    |   3 +
 lib/dynamic_debug.c                  | 133 ++++++++++++++++++++++++-----------
 13 files changed, 251 insertions(+), 136 deletions(-)
 create mode 100644 arch/x86/include/asm/dynamic_debug.h

-- 
2.16.4

[PATCH 14/22] btrfs: implement btrfs_debug* in terms of helper macro

[Rasmus Villemoes]

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the HAVE_JUMP_LABEL
optimization.

Second, changes on x86-64 later in this series require that all struct
_ddebug descriptors in a translation unit use distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these.

Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/btrfs/ctree.h | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2cddfe7806a4..7ae6cdad5b38 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3353,31 +3353,17 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
 
 #if defined(CONFIG_DYNAMIC_DEBUG)
 #define btrfs_debug(fs_info, fmt, args...)				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk(fs_info, KERN_DEBUG fmt, ##args);		\
-} while (0)
-#define btrfs_debug_in_rcu(fs_info, fmt, args...) 			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); 	        \
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) 		\
-		btrfs_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args);	\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk,			\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_in_rcu(fs_info, fmt, args...)			\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...)			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_rl_in_rcu(fs_info, KERN_DEBUG fmt,		\
-				       ##args);\
-} while (0)
-#define btrfs_debug_rl(fs_info, fmt, args...) 				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_ratelimited(fs_info, KERN_DEBUG fmt,	\
-					 ##args);			\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_rl_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_rl(fs_info, fmt, args...)				\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_ratelimited,	\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)
-- 
2.16.4

Re: [PATCH 00/22] various dynamic_debug patches

[Rafael J. Wysocki]

On Thursday, September 20, 2018 12:04:22 AM CEST Rasmus Villemoes wrote:
> This started as an experiment to see how hard it would be to change
> the four pointers in struct _ddebug into relative offsets, a la
> CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
> pr_debug site (and thus exactly making up for the extra space used by
> the introduction of jump labels in 9049fc74). I stumbled on a few
> things that are probably worth fixing regardless of whether the latter
> half of this series is deemed worthwhile.
> 
> Patch relationships: 1-2, 3-4, 5-6 and 15-16 can be applied
> individually, though 2, 4 and 6 probably makes most sense in the
> context of the final goal of the series.

OK, I can take the [15-16/22] separately.

Thanks,
Rafael

Re: [PATCH 14/22] btrfs: implement btrfs_debug* in terms of helper macro

[David Sterba]

On Thu, Sep 20, 2018 at 12:04:36AM +0200, Rasmus Villemoes wrote:
> First, the btrfs_debug macros open-code (one possible definition of)
> DYNAMIC_DEBUG_BRANCH, so they don't benefit from the HAVE_JUMP_LABEL
> optimization.
> 
> Second, changes on x86-64 later in this series require that all struct
> _ddebug descriptors in a translation unit use distinct identifiers.
> 
> Using the new _dynamic_func_call_no_desc helper macro from
> dynamic_debug.h takes care of both of these.
> 
> Cc: linux-btrfs@vger.kernel.org
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Acked-by: David Sterba <dsterba@suse.com>

Per the cover letter, I assume you'll take it through your git tree.

Re: [PATCH 14/22] btrfs: implement btrfs_debug* in terms of helper macro

[Rasmus Villemoes]

On 2018-09-20 15:10, David Sterba wrote:
> On Thu, Sep 20, 2018 at 12:04:36AM +0200, Rasmus Villemoes wrote:
>> First, the btrfs_debug macros open-code (one possible definition of)
>> DYNAMIC_DEBUG_BRANCH, so they don't benefit from the HAVE_JUMP_LABEL
>> optimization.
>>
>> Second, changes on x86-64 later in this series require that all struct
>> _ddebug descriptors in a translation unit use distinct identifiers.
>>
>> Using the new _dynamic_func_call_no_desc helper macro from
>> dynamic_debug.h takes care of both of these.
>>
>> Cc: linux-btrfs@vger.kernel.org
>> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> 
> Acked-by: David Sterba <dsterba@suse.com>
> 
> Per the cover letter, I assume you'll take it through your git tree.

Thanks. I don't have a git tree feeding to -next myself, but these will
probably be routed through akpm or x86.

Rasmus

Re: [PATCH 00/22] various dynamic_debug patches

[Jason Baron]

On 09/19/2018 06:04 PM, Rasmus Villemoes wrote:
> This started as an experiment to see how hard it would be to change
> the four pointers in struct _ddebug into relative offsets, a la
> CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
> pr_debug site (and thus exactly making up for the extra space used by
> the introduction of jump labels in 9049fc74). I stumbled on a few
> things that are probably worth fixing regardless of whether the latter
> half of this series is deemed worthwhile.
> 
> Patch relationships: 1-2, 3-4, 5-6 and 15-16 can be applied
> individually, though 2, 4 and 6 probably makes most sense in the
> context of the final goal of the series.
> 
> 7-12 I believe make sense on their own. Patch 13 again only makes
> sense if we go all the way, and 14 and 17 depend on 13.
> 
> 18-21 are more preparatory patches, and finally 22 switch over x86-64
> to use CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS. I've tested that the
> end result boots under virtme and that the dynamic_debug control file
> has the expected contents.
> 

I would like to to see all these patches included. Feel free to add:
Acked-by: Jason Baron <jbaron@akamai.com>

I've been wanting to add DYNAMIC_DEBUG_BRANCH to the
[dev,net,pr].*ratelimited functions. That should reduce the size of the
text as well.

Thanks,

-Jason

Re: [PATCH 00/22] various dynamic_debug patches

[Rafael J. Wysocki]

On Thursday, September 20, 2018 10:05:00 AM CEST Rafael J. Wysocki wrote:
> On Thursday, September 20, 2018 12:04:22 AM CEST Rasmus Villemoes wrote:
> > This started as an experiment to see how hard it would be to change
> > the four pointers in struct _ddebug into relative offsets, a la
> > CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
> > pr_debug site (and thus exactly making up for the extra space used by
> > the introduction of jump labels in 9049fc74). I stumbled on a few
> > things that are probably worth fixing regardless of whether the latter
> > half of this series is deemed worthwhile.
> > 
> > Patch relationships: 1-2, 3-4, 5-6 and 15-16 can be applied
> > individually, though 2, 4 and 6 probably makes most sense in the
> > context of the final goal of the series.
> 
> OK, I can take the [15-16/22] separately.

And they have been applied now.

Thanks,
Rafael

[PATCH v2 00/23] various dynamic_debug patches

[Rasmus Villemoes]

v2: Added various acks/reviews. I'll follow up with rewriting the x86
part as asm macros once that work is in mainline.

Patches 15, 16 are in next-20181009; in hindsight I should probably
have asked Rafael not to pick those. Patch 17 textually depend on
those, and patch 19 removes the .flags field, so depends on 15 so that
there are no references to that field. I'm included all patches here
hoping that the merge conflicts are trivial, given that it's just same
patches present in multiple branches.

Andrew, can you pick up these to give them some time in -next?

v1 cover letter:

This started as an experiment to see how hard it would be to change
the four pointers in struct _ddebug into relative offsets, a la
CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
pr_debug site (and thus exactly making up for the extra space used by
the introduction of jump labels in 9049fc74). I stumbled on a few
things that are probably worth fixing regardless of whether the latter
half of this series is deemed worthwhile.

Patch relationships: 1-2, 3-4, 5-6 and 15-16 can be applied
individually, though 2, 4 and 6 probably makes most sense in the
context of the final goal of the series.

7-12 I believe make sense on their own. Patch 13 again only makes
sense if we go all the way, and 14 and 17 depend on 13.

18-21 are more preparatory patches, and finally 22 switch over x86-64
to use CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS. I've tested that the
end result boots under virtme and that the dynamic_debug control file
has the expected contents.

Rasmus Villemoes (23):
  linux/device.h: use DYNAMIC_DEBUG_BRANCH in dev_dbg_ratelimited
  linux/device.h: use unique identifier for each struct _ddebug
  linux/net.h: use DYNAMIC_DEBUG_BRANCH in net_dbg_ratelimited
  linux/net.h: use unique identifier for each struct _ddebug
  linux/printk.h: use DYNAMIC_DEBUG_BRANCH in pr_debug_ratelimited
  linux/printk.h: use unique identifier for each struct _ddebug
  dynamic_debug: consolidate DEFINE_DYNAMIC_DEBUG_METADATA definitions
  dynamic_debug: don't duplicate modname in ddebug_add_module
  dynamic_debug: use pointer comparison in ddebug_remove_module
  dynamic_debug: remove unused EXPORT_SYMBOLs
  dynamic_debug: move pr_err from module.c to ddebug_add_module
  dynamic_debug: add static inline stub for ddebug_add_module
  dynamic_debug: refactor dynamic_pr_debug and friends
  btrfs: implement btrfs_debug* in terms of helper macro
  ACPI: use proper DYNAMIC_DEBUG_BRANCH macro
  ACPI: remove unused __acpi_handle_debug macro
  ACPI: implement acpi_handle_debug in terms of _dynamic_func_call
  dynamic_debug: introduce accessors for string members of struct
    _ddebug
  dynamic_debug: drop use of bitfields in struct _ddebug
  dynamic_debug: introduce CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS
  x86: jump_label: introduce ASM_STATIC_KEY_INIT_{TRUE,FALSE}
  x86_64: use relative pointers with dynamic debug
  x86: dynamic_debug: protect against dynamic debug identifier reuse

 arch/x86/Kconfig                     |   1 +
 arch/x86/include/asm/dynamic_debug.h |  40 ++++++++
 arch/x86/include/asm/jump_label.h    |  18 ++++
 fs/btrfs/ctree.h                     |  34 ++-----
 include/linux/acpi.h                 |  11 +--
 include/linux/device.h               |   6 +-
 include/linux/dynamic_debug.h        | 126 +++++++++++++++----------
 include/linux/jump_label.h           |   2 +
 include/linux/net.h                  |   6 +-
 include/linux/printk.h               |   6 +-
 kernel/module.c                      |   6 +-
 lib/Kconfig.debug                    |   3 +
 lib/dynamic_debug.c                  | 133 ++++++++++++++++++---------
 13 files changed, 256 insertions(+), 136 deletions(-)
 create mode 100644 arch/x86/include/asm/dynamic_debug.h

-- 
2.19.1.3.g1d92a00e68

[PATCH v2 14/23] btrfs: implement btrfs_debug* in terms of helper macro

[Rasmus Villemoes]

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the HAVE_JUMP_LABEL
optimization.

Second, changes on x86-64 later in this series require that all struct
_ddebug descriptors in a translation unit use distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these.

Cc: linux-btrfs@vger.kernel.org
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/btrfs/ctree.h | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2cddfe7806a4..7ae6cdad5b38 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3353,31 +3353,17 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
 
 #if defined(CONFIG_DYNAMIC_DEBUG)
 #define btrfs_debug(fs_info, fmt, args...)				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk(fs_info, KERN_DEBUG fmt, ##args);		\
-} while (0)
-#define btrfs_debug_in_rcu(fs_info, fmt, args...) 			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); 	        \
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) 		\
-		btrfs_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args);	\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk,			\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_in_rcu(fs_info, fmt, args...)			\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...)			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_rl_in_rcu(fs_info, KERN_DEBUG fmt,		\
-				       ##args);\
-} while (0)
-#define btrfs_debug_rl(fs_info, fmt, args...) 				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_ratelimited(fs_info, KERN_DEBUG fmt,	\
-					 ##args);			\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_rl_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_rl(fs_info, fmt, args...)				\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_ratelimited,	\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)
-- 
2.19.1.3.g1d92a00e68

Re: [PATCH v2 00/23] various dynamic_debug patches

[Rafael J. Wysocki]

On Tue, Oct 9, 2018 at 1:20 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> v2: Added various acks/reviews. I'll follow up with rewriting the x86
> part as asm macros once that work is in mainline.
>
> Patches 15, 16 are in next-20181009; in hindsight I should probably
> have asked Rafael not to pick those.

So I have dropped them (which was easy enough to do).

Thanks,
Rafael

[PATCH v3 00/23] various dynamic_debug patches

[Rasmus Villemoes]

This started as an experiment to see how hard it would be to change
the four pointers in struct _ddebug into relative offsets, a la
CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
pr_debug site (and thus exactly making up for the extra space used by
the introduction of jump labels in 9049fc74). I stumbled on a few
things that are probably worth fixing regardless of whether that goal
is deemed worthwhile.

v2: Added various acks/reviews.

v3: Rebased on top of v4.20-rc1, and (consequently) reimplemented the
x86 part using Nadav's asm macro infrastructure. I've taken the
liberty of preserving acks/reviews for the first 20, since the rebase
was completely clean. OTOH, I've removed any acks/reviews from the
last three patches, since they are essentially completely new in this
version.

Since there are some interdependencies, it's simplest if these go
through the same tree. Andrew, can I get you to pick up patches 1
through 17? They should be ready for some time in -next. If and when
the last three (new) patches get ack'ed, I'll ask you to pick up the
last 6 (Jason has ack'ed 18-20, but they don't make much sense without
at least one arch opting in to use DYNAMIC_DEBUG_RELATIVE_POINTERS).

Rasmus Villemoes (23):
  linux/device.h: use DYNAMIC_DEBUG_BRANCH in dev_dbg_ratelimited
  linux/device.h: use unique identifier for each struct _ddebug
  linux/net.h: use DYNAMIC_DEBUG_BRANCH in net_dbg_ratelimited
  linux/net.h: use unique identifier for each struct _ddebug
  linux/printk.h: use DYNAMIC_DEBUG_BRANCH in pr_debug_ratelimited
  linux/printk.h: use unique identifier for each struct _ddebug
  dynamic_debug: consolidate DEFINE_DYNAMIC_DEBUG_METADATA definitions
  dynamic_debug: don't duplicate modname in ddebug_add_module
  dynamic_debug: use pointer comparison in ddebug_remove_module
  dynamic_debug: remove unused EXPORT_SYMBOLs
  dynamic_debug: move pr_err from module.c to ddebug_add_module
  dynamic_debug: add static inline stub for ddebug_add_module
  dynamic_debug: refactor dynamic_pr_debug and friends
  btrfs: implement btrfs_debug* in terms of helper macro
  ACPI: use proper DYNAMIC_DEBUG_BRANCH macro
  ACPI: remove unused __acpi_handle_debug macro
  ACPI: implement acpi_handle_debug in terms of _dynamic_func_call
  dynamic_debug: introduce accessors for string members of struct
    _ddebug
  dynamic_debug: drop use of bitfields in struct _ddebug
  dynamic_debug: introduce CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS
  jump_label: move JUMP_TYPE_* constants to new asm-generic file
  x86: jump_label: introduce asm macros STATIC_KEY_INIT{,_TRUE,_FALSE}
  x86_64: use relative pointers with dynamic debug

 arch/x86/Kconfig                     |   1 +
 arch/x86/include/asm/dynamic_debug.h |  58 ++++++++++++
 arch/x86/include/asm/jump_label.h    |  17 ++++
 arch/x86/kernel/macros.S             |   1 +
 fs/btrfs/ctree.h                     |  34 ++-----
 include/asm-generic/jump_label.h     |  11 +++
 include/linux/acpi.h                 |  11 +--
 include/linux/device.h               |   6 +-
 include/linux/dynamic_debug.h        | 126 +++++++++++++++----------
 include/linux/jump_label.h           |   6 +-
 include/linux/net.h                  |   6 +-
 include/linux/printk.h               |   6 +-
 kernel/module.c                      |   6 +-
 lib/Kconfig.debug                    |   3 +
 lib/dynamic_debug.c                  | 133 ++++++++++++++++++---------
 15 files changed, 284 insertions(+), 141 deletions(-)
 create mode 100644 arch/x86/include/asm/dynamic_debug.h
 create mode 100644 include/asm-generic/jump_label.h

-- 
2.19.1.6.gbde171bbf5

[PATCH v3 14/23] btrfs: implement btrfs_debug* in terms of helper macro

[Rasmus Villemoes]

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the HAVE_JUMP_LABEL
optimization.

Second, changes on x86-64 later in this series require that all struct
_ddebug descriptors in a translation unit use distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these.

Cc: linux-btrfs@vger.kernel.org
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/btrfs/ctree.h | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 80953528572d..0d55bf56872f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3334,31 +3334,17 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
 
 #if defined(CONFIG_DYNAMIC_DEBUG)
 #define btrfs_debug(fs_info, fmt, args...)				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk(fs_info, KERN_DEBUG fmt, ##args);		\
-} while (0)
-#define btrfs_debug_in_rcu(fs_info, fmt, args...) 			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); 	        \
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) 		\
-		btrfs_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args);	\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk,			\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_in_rcu(fs_info, fmt, args...)			\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...)			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_rl_in_rcu(fs_info, KERN_DEBUG fmt,		\
-				       ##args);\
-} while (0)
-#define btrfs_debug_rl(fs_info, fmt, args...) 				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_ratelimited(fs_info, KERN_DEBUG fmt,	\
-					 ##args);			\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_rl_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_rl(fs_info, fmt, args...)				\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_ratelimited,	\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)
-- 
2.19.1.6.gbde171bbf5

[PATCH v4 00/14] various dynamic_debug patches

[Rasmus Villemoes]

This started as an experiment to see how hard it would be to change
the four pointers in struct _ddebug into relative offsets, a la
CONFIG_GENERIC_BUG_RELATIVE_POINTERS, thus saving 16 bytes per
pr_debug site (and thus exactly making up for the extra space used by
the introduction of jump labels in 9049fc74). I stumbled on a few
things that are probably worth fixing regardless of whether that goal
is deemed worthwhile.

Back at v3 (in November), I redid the implementation on top of the
fancy new asm-macros stuff. Luckily enough, v3 didn't get picked up,
since the asm-macros were backed out again. I still want to do the
relative-pointers thing eventually, but we're close to the merge
window opening, so here's just most of the "incidental" patches, some
of which also serve as preparation for the relative pointers.

I'm not sure how long an Ack/Reviewed-by is good for, but OTOH it also
feels rude to just drop them on the floor. I've kept those tags since
the rebasing to current master went completely smooth.

Andrew, please pick these up for soaking in -next.

v3 series: lkml.kernel.org/r/20181109231021.11658-1-linux@rasmusvillemoes.dk
v2 series: lkml.kernel.org/r/20181009112013.14238-1-linux@rasmusvillemoes.dk

Rasmus Villemoes (14):
  linux/device.h: use DYNAMIC_DEBUG_BRANCH in dev_dbg_ratelimited
  linux/net.h: use DYNAMIC_DEBUG_BRANCH in net_dbg_ratelimited
  linux/printk.h: use DYNAMIC_DEBUG_BRANCH in pr_debug_ratelimited
  dynamic_debug: consolidate DEFINE_DYNAMIC_DEBUG_METADATA definitions
  dynamic_debug: don't duplicate modname in ddebug_add_module
  dynamic_debug: use pointer comparison in ddebug_remove_module
  dynamic_debug: remove unused EXPORT_SYMBOLs
  dynamic_debug: move pr_err from module.c to ddebug_add_module
  dynamic_debug: add static inline stub for ddebug_add_module
  dynamic_debug: refactor dynamic_pr_debug and friends
  btrfs: implement btrfs_debug* in terms of helper macro
  ACPI: use proper DYNAMIC_DEBUG_BRANCH macro
  ACPI: remove unused __acpi_handle_debug macro
  ACPI: implement acpi_handle_debug in terms of _dynamic_func_call

 fs/btrfs/ctree.h              |  34 ++++--------
 include/linux/acpi.h          |  11 +---
 include/linux/device.h        |   2 +-
 include/linux/dynamic_debug.h | 102 +++++++++++++++++++---------------
 include/linux/net.h           |   2 +-
 include/linux/printk.h        |   2 +-
 kernel/module.c               |   6 +-
 lib/dynamic_debug.c           |  22 ++++----
 8 files changed, 84 insertions(+), 97 deletions(-)

-- 
2.20.1

[PATCH v4 11/14] btrfs: implement btrfs_debug* in terms of helper macro

[Rasmus Villemoes]

First, the btrfs_debug macros open-code (one possible definition of)
DYNAMIC_DEBUG_BRANCH, so they don't benefit from the CONFIG_JUMP_LABEL
optimization.

Second, a planned change of struct _ddebug (to reduce its size on 64
bit machines) requires that all descriptors in a translation unit use
distinct identifiers.

Using the new _dynamic_func_call_no_desc helper macro from
dynamic_debug.h takes care of both of these. No functional change.

Cc: linux-btrfs@vger.kernel.org
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 fs/btrfs/ctree.h | 34 ++++++++++------------------------
 1 file changed, 10 insertions(+), 24 deletions(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 7a2a2621f0d9..94618a028730 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3415,31 +3415,17 @@ void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...);
 
 #if defined(CONFIG_DYNAMIC_DEBUG)
 #define btrfs_debug(fs_info, fmt, args...)				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk(fs_info, KERN_DEBUG fmt, ##args);		\
-} while (0)
-#define btrfs_debug_in_rcu(fs_info, fmt, args...) 			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); 	        \
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT)) 		\
-		btrfs_printk_in_rcu(fs_info, KERN_DEBUG fmt, ##args);	\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk,			\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_in_rcu(fs_info, fmt, args...)			\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #define btrfs_debug_rl_in_rcu(fs_info, fmt, args...)			\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_rl_in_rcu(fs_info, KERN_DEBUG fmt,		\
-				       ##args);\
-} while (0)
-#define btrfs_debug_rl(fs_info, fmt, args...) 				\
-do {									\
-        DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt);         	\
-        if (unlikely(descriptor.flags & _DPRINTK_FLAGS_PRINT))  	\
-		btrfs_printk_ratelimited(fs_info, KERN_DEBUG fmt,	\
-					 ##args);			\
-} while (0)
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_rl_in_rcu,		\
+				   fs_info, KERN_DEBUG fmt, ##args)
+#define btrfs_debug_rl(fs_info, fmt, args...)				\
+	_dynamic_func_call_no_desc(fmt, btrfs_printk_ratelimited,	\
+				   fs_info, KERN_DEBUG fmt, ##args)
 #elif defined(DEBUG)
 #define btrfs_debug(fs_info, fmt, args...) \
 	btrfs_printk(fs_info, KERN_DEBUG fmt, ##args)
-- 
2.20.1