[PATCH v4 0/3] printk: CONFIG_BASE_SMALL fix for LOG_CPU_MAX_BUF_SHIFT and removal of CONFIG_BASE_FULL

[PATCH v4 0/3] printk: CONFIG_BASE_SMALL fix for LOG_CPU_MAX_BUF_SHIFT and removal of CONFIG_BASE_FULL

[Yoann Congal]

This series focuses on CONFIG_BASE_SMALL.
The first patch fixes LOG_CPU_MAX_BUF_SHIFT when CONFIG_BASE_SMALL is
used.
The second patch globally changes the type of CONFIG_BASE_SMALL and
adapts usages.
The third patch removes the now redundant BASE_FULL and puts BASE_SMALL
in its place in the config menus.

Thanks everyone for your reviews! :)

Patch history:
v3->v4: Applied Petr Mladek's suggestion (Thanks!):
* Keep BASE_SMALL instead of BASE_FULL
* A patch changing the type of BASE_SMALL was added.

v3 series was named "printk: CONFIG_BASE_SMALL fix for
LOG_CPU_MAX_BUF_SHIFT and removal"
https://lore.kernel.org/all/20240204232945.1576403-1-yoann.congal@smile.fr/
* Patch v3 1/2:
  * Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
  * Reviewed-by: John Ogness <john.ogness@linutronix.de>
  * Reviewed-by: Petr Mladek <pmladek@suse.com>
* Patch v3 2/2:
  * Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>

v2 -> v3: Applied Luis Chamberlain's comments (Thanks!):
* Split the single commit in two : one functional fix, one global
  removal.

v2 patch was named "printk: Remove redundant CONFIG_BASE_SMALL"
https://lore.kernel.org/all/20240127220026.1722399-1-yoann.congal@smile.fr/
* Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
* Reviewed-by: John Ogness <john.ogness@linutronix.de>

v1 -> v2: Applied Masahiro Yamada's comments (Thanks!):
* Changed from "Change CONFIG_BASE_SMALL to type bool" to
  "Remove it and switch usage to !CONFIG_BASE_FULL"
* Fixed "Fixes:" tag and reference to the mailing list thread.
* Added a note about CONFIG_LOG_CPU_MAX_BUF_SHIFT changing.

v1 patch was named "treewide: Change CONFIG_BASE_SMALL to bool type"
https://lore.kernel.org/all/20240126163032.1613731-1-yoann.congal@smile.fr/

Yoann Congal (3):
  printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled
  printk: Change type of CONFIG_BASE_SMALL to bool
  printk: Remove redundant CONFIG_BASE_FULL

 arch/x86/include/asm/mpspec.h |  6 +++---
 drivers/tty/vt/vc_screen.c    |  2 +-
 include/linux/threads.h       |  4 ++--
 include/linux/udp.h           |  2 +-
 include/linux/xarray.h        |  2 +-
 init/Kconfig                  | 15 +++++----------
 kernel/futex/core.c           |  2 +-
 kernel/user.c                 |  2 +-
 8 files changed, 15 insertions(+), 20 deletions(-)

-- 
2.39.2

[PATCH v4 1/3] printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled

[Yoann Congal]

LOG_CPU_MAX_BUF_SHIFT default value depends on BASE_SMALL:
  config LOG_CPU_MAX_BUF_SHIFT
  	default 12 if !BASE_SMALL
  	default 0 if BASE_SMALL
But, BASE_SMALL is a config of type int and "!BASE_SMALL" is always
evaluated to true whatever is the value of BASE_SMALL.

This patch fixes this by using the correct conditional operator for int
type : BASE_SMALL != 0.

Note: This changes CONFIG_LOG_CPU_MAX_BUF_SHIFT=12 to
CONFIG_LOG_CPU_MAX_BUF_SHIFT=0 for BASE_SMALL defconfigs, but that will
not be a big impact due to this code in kernel/printk/printk.c:
  /* by default this will only continue through for large > 64 CPUs */
  if (cpu_extra <= __LOG_BUF_LEN / 2)
          return;
Systems using CONFIG_BASE_SMALL and having 64+ CPUs should be quite
rare.

John Ogness <john.ogness@linutronix.de> (printk reviewer) wrote:
> For printk this will mean that BASE_SMALL systems were probably
> previously allocating/using the dynamic ringbuffer and now they will
> just continue to use the static ringbuffer. Which is fine and saves
> memory (as it should).

Petr Mladek <pmladek@suse.com> (printk maintainer) wrote:
> More precisely, it allocated the buffer dynamically when the sum
> of per-CPU-extra space exceeded half of the default static ring
> buffer. This happened for systems with more than 64 CPUs with
> the default config values.

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/all/CAMuHMdWm6u1wX7efZQf=2XUAHascps76YQac6rdnQGhc8nop_Q@mail.gmail.com/
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Closes: https://lore.kernel.org/all/f6856be8-54b7-0fa0-1d17-39632bf29ada@oracle.com/
Fixes: 4e244c10eab3 ("kconfig: remove unneeded symbol_empty variable")

---
v3->v4:
* Fix BASE_SMALL usage instead of switching to BASE_FULL because
  BASE_FULL will be removed in the next patches of this series.
---
 init/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index deda3d14135bb..d50ebd2a2ce42 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -734,8 +734,8 @@ config LOG_CPU_MAX_BUF_SHIFT
 	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
 	depends on SMP
 	range 0 21
-	default 12 if !BASE_SMALL
-	default 0 if BASE_SMALL
+	default 0 if BASE_SMALL != 0
+	default 12
 	depends on PRINTK
 	help
 	  This option allows to increase the default ring buffer size
-- 
2.39.2

[PATCH v4 2/3] printk: Change type of CONFIG_BASE_SMALL to bool

[Yoann Congal]

CONFIG_BASE_SMALL is currently a type int but is only used as a boolean.

So, change its type to bool and adapt all usages:
CONFIG_BASE_SMALL == 0 becomes !IS_ENABLED(CONFIG_BASE_SMALL) and
CONFIG_BASE_SMALL != 0 becomes  IS_ENABLED(CONFIG_BASE_SMALL).

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
NB: This is preliminary work for the following patch removing
CONFIG_BASE_FULL (now equivalent to !CONFIG_BASE_SMALL)

v3->v4:
* Split "switch CONFIG_BASE_SMALL to bool" (this patch) and "Remove the redundant
  config" into two patches
* keep CONFIG_BASE_SMALL instead of CONFIG_BASE_FULL
---
 arch/x86/include/asm/mpspec.h | 6 +++---
 drivers/tty/vt/vc_screen.c    | 2 +-
 include/linux/threads.h       | 4 ++--
 include/linux/udp.h           | 2 +-
 include/linux/xarray.h        | 2 +-
 init/Kconfig                  | 8 ++++----
 kernel/futex/core.c           | 2 +-
 kernel/user.c                 | 2 +-
 8 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
index 4b0f98a8d338d..c01d3105840cf 100644
--- a/arch/x86/include/asm/mpspec.h
+++ b/arch/x86/include/asm/mpspec.h
@@ -15,10 +15,10 @@ extern int pic_mode;
  * Summit or generic (i.e. installer) kernels need lots of bus entries.
  * Maximum 256 PCI busses, plus 1 ISA bus in each of 4 cabinets.
  */
-#if CONFIG_BASE_SMALL == 0
-# define MAX_MP_BUSSES		260
-#else
+#ifdef CONFIG_BASE_SMALL
 # define MAX_MP_BUSSES		32
+#else
+# define MAX_MP_BUSSES		260
 #endif
 
 #define MAX_IRQ_SOURCES		256
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 67e2cb7c96eec..da33c6c4691c0 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -51,7 +51,7 @@
 #include <asm/unaligned.h>
 
 #define HEADER_SIZE	4u
-#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
+#define CON_BUF_SIZE (IS_ENABLED(CONFIG_BASE_SMALL) ? 256 : PAGE_SIZE)
 
 /*
  * Our minor space:
diff --git a/include/linux/threads.h b/include/linux/threads.h
index c34173e6c5f18..1674a471b0b4c 100644
--- a/include/linux/threads.h
+++ b/include/linux/threads.h
@@ -25,13 +25,13 @@
 /*
  * This controls the default maximum pid allocated to a process
  */
-#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
+#define PID_MAX_DEFAULT (IS_ENABLED(CONFIG_BASE_SMALL) ? 0x1000 : 0x8000)
 
 /*
  * A maximum of 4 million PIDs should be enough for a while.
  * [NOTE: PID/TIDs are limited to 2^30 ~= 1 billion, see FUTEX_TID_MASK.]
  */
-#define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
+#define PID_MAX_LIMIT (IS_ENABLED(CONFIG_BASE_SMALL) ? PAGE_SIZE * 8 : \
 	(sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
 
 /*
diff --git a/include/linux/udp.h b/include/linux/udp.h
index d04188714dca1..b456417fb4515 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -24,7 +24,7 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
 }
 
 #define UDP_HTABLE_SIZE_MIN_PERNET	128
-#define UDP_HTABLE_SIZE_MIN		(CONFIG_BASE_SMALL ? 128 : 256)
+#define UDP_HTABLE_SIZE_MIN		(IS_ENABLED(CONFIG_BASE_SMALL) ? 128 : 256)
 #define UDP_HTABLE_SIZE_MAX		65536
 
 static inline u32 udp_hashfn(const struct net *net, u32 num, u32 mask)
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index cb571dfcf4b16..3f81ee5f9fb9c 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -1141,7 +1141,7 @@ static inline void xa_release(struct xarray *xa, unsigned long index)
  * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
  */
 #ifndef XA_CHUNK_SHIFT
-#define XA_CHUNK_SHIFT		(CONFIG_BASE_SMALL ? 4 : 6)
+#define XA_CHUNK_SHIFT		(IS_ENABLED(CONFIG_BASE_SMALL) ? 4 : 6)
 #endif
 #define XA_CHUNK_SIZE		(1UL << XA_CHUNK_SHIFT)
 #define XA_CHUNK_MASK		(XA_CHUNK_SIZE - 1)
diff --git a/init/Kconfig b/init/Kconfig
index d50ebd2a2ce42..d4b16cad98502 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -734,7 +734,7 @@ config LOG_CPU_MAX_BUF_SHIFT
 	int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
 	depends on SMP
 	range 0 21
-	default 0 if BASE_SMALL != 0
+	default 0 if BASE_SMALL
 	default 12
 	depends on PRINTK
 	help
@@ -1941,9 +1941,9 @@ config RT_MUTEXES
 	default y if PREEMPT_RT
 
 config BASE_SMALL
-	int
-	default 0 if BASE_FULL
-	default 1 if !BASE_FULL
+	bool
+	default y if !BASE_FULL
+	default n
 
 config MODULE_SIG_FORMAT
 	def_bool n
diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index 1e78ef24321e8..06a1f091be81d 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -1150,7 +1150,7 @@ static int __init futex_init(void)
 	unsigned int futex_shift;
 	unsigned long i;
 
-#if CONFIG_BASE_SMALL
+#ifdef CONFIG_BASE_SMALL
 	futex_hashsize = 16;
 #else
 	futex_hashsize = roundup_pow_of_two(256 * num_possible_cpus());
diff --git a/kernel/user.c b/kernel/user.c
index 03cedc366dc9e..aa1162deafe49 100644
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -88,7 +88,7 @@ EXPORT_SYMBOL_GPL(init_user_ns);
  * when changing user ID's (ie setuid() and friends).
  */
 
-#define UIDHASH_BITS	(CONFIG_BASE_SMALL ? 3 : 7)
+#define UIDHASH_BITS	(IS_ENABLED(CONFIG_BASE_SMALL) ? 3 : 7)
 #define UIDHASH_SZ	(1 << UIDHASH_BITS)
 #define UIDHASH_MASK		(UIDHASH_SZ - 1)
 #define __uidhashfn(uid)	(((uid >> UIDHASH_BITS) + uid) & UIDHASH_MASK)
-- 
2.39.2

[PATCH v4 3/3] printk: Remove redundant CONFIG_BASE_FULL

[Yoann Congal]

CONFIG_BASE_FULL is equivalent to !CONFIG_BASE_SMALL and is enabled by
default: CONFIG_BASE_SMALL is the special case to take care of.
So, remove CONFIG_BASE_FULL and move the config choice to
CONFIG_BASE_SMALL (which defaults to 'n')

Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
---
v3->v4:
* Split "switch CONFIG_BASE_SMALL to bool" and "Remove the redundant
  config" (this patch) into two patches
* keep CONFIG_BASE_SMALL instead of CONFIG_BASE_FULL
---
 init/Kconfig | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index d4b16cad98502..4ecf2572d00ee 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1581,11 +1581,11 @@ config PCSPKR_PLATFORM
 	  This option allows to disable the internal PC-Speaker
 	  support, saving some memory.
 
-config BASE_FULL
-	default y
-	bool "Enable full-sized data structures for core" if EXPERT
+config BASE_SMALL
+	default n
+	bool "Enable smaller-sized data structures for core" if EXPERT
 	help
-	  Disabling this option reduces the size of miscellaneous core
+	  Enabling this option reduces the size of miscellaneous core
 	  kernel data structures. This saves memory on small machines,
 	  but may reduce performance.
 
@@ -1940,11 +1940,6 @@ config RT_MUTEXES
 	bool
 	default y if PREEMPT_RT
 
-config BASE_SMALL
-	bool
-	default y if !BASE_FULL
-	default n
-
 config MODULE_SIG_FORMAT
 	def_bool n
 	select SYSTEM_DATA_VERIFICATION
-- 
2.39.2

Re: [PATCH v4 1/3] printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled

[Petr Mladek]

On Tue 2024-02-06 01:13:31, Yoann Congal wrote:
> LOG_CPU_MAX_BUF_SHIFT default value depends on BASE_SMALL:
>   config LOG_CPU_MAX_BUF_SHIFT
>   	default 12 if !BASE_SMALL
>   	default 0 if BASE_SMALL
> But, BASE_SMALL is a config of type int and "!BASE_SMALL" is always
> evaluated to true whatever is the value of BASE_SMALL.
> 
> This patch fixes this by using the correct conditional operator for int
> type : BASE_SMALL != 0.
> 
> Note: This changes CONFIG_LOG_CPU_MAX_BUF_SHIFT=12 to
> CONFIG_LOG_CPU_MAX_BUF_SHIFT=0 for BASE_SMALL defconfigs, but that will
> not be a big impact due to this code in kernel/printk/printk.c:
>   /* by default this will only continue through for large > 64 CPUs */
>   if (cpu_extra <= __LOG_BUF_LEN / 2)
>           return;
> Systems using CONFIG_BASE_SMALL and having 64+ CPUs should be quite
> rare.
> 
> John Ogness <john.ogness@linutronix.de> (printk reviewer) wrote:
> > For printk this will mean that BASE_SMALL systems were probably
> > previously allocating/using the dynamic ringbuffer and now they will
> > just continue to use the static ringbuffer. Which is fine and saves
> > memory (as it should).
> 
> Petr Mladek <pmladek@suse.com> (printk maintainer) wrote:
> > More precisely, it allocated the buffer dynamically when the sum
> > of per-CPU-extra space exceeded half of the default static ring
> > buffer. This happened for systems with more than 64 CPUs with
> > the default config values.
> 
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Closes: https://lore.kernel.org/all/CAMuHMdWm6u1wX7efZQf=2XUAHascps76YQac6rdnQGhc8nop_Q@mail.gmail.com/
> Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
> Closes: https://lore.kernel.org/all/f6856be8-54b7-0fa0-1d17-39632bf29ada@oracle.com/
> Fixes: 4e244c10eab3 ("kconfig: remove unneeded symbol_empty variable")

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH v4 2/3] printk: Change type of CONFIG_BASE_SMALL to bool

[Petr Mladek]

On Tue 2024-02-06 01:13:32, Yoann Congal wrote:
> CONFIG_BASE_SMALL is currently a type int but is only used as a boolean.
> 
> So, change its type to bool and adapt all usages:
> CONFIG_BASE_SMALL == 0 becomes !IS_ENABLED(CONFIG_BASE_SMALL) and
> CONFIG_BASE_SMALL != 0 becomes  IS_ENABLED(CONFIG_BASE_SMALL).
> 
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr

Re: [PATCH v4 3/3] printk: Remove redundant CONFIG_BASE_FULL

[Petr Mladek]

On Tue 2024-02-06 01:13:33, Yoann Congal wrote:
> CONFIG_BASE_FULL is equivalent to !CONFIG_BASE_SMALL and is enabled by
> default: CONFIG_BASE_SMALL is the special case to take care of.
> So, remove CONFIG_BASE_FULL and move the config choice to
> CONFIG_BASE_SMALL (which defaults to 'n')
> 
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>

This might also require updatating the default config files which
unset CONFIG_BASE_FULL. I mean:

$> git grep BASE_FULL arch/
arch/arm/configs/collie_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/keystone_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/lpc18xx_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/moxart_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/mps2_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/omap1_defconfig:# CONFIG_BASE_FULL is not set
arch/arm/configs/stm32_defconfig:# CONFIG_BASE_FULL is not set
arch/microblaze/configs/mmu_defconfig:# CONFIG_BASE_FULL is not set
arch/mips/configs/rs90_defconfig:# CONFIG_BASE_FULL is not set
arch/powerpc/configs/adder875_defconfig:# CONFIG_BASE_FULL is not set
arch/powerpc/configs/ep88xc_defconfig:# CONFIG_BASE_FULL is not set
arch/powerpc/configs/mpc866_ads_defconfig:# CONFIG_BASE_FULL is not set
arch/powerpc/configs/mpc885_ads_defconfig:# CONFIG_BASE_FULL is not set
arch/powerpc/configs/tqm8xx_defconfig:# CONFIG_BASE_FULL is not set
arch/riscv/configs/nommu_k210_defconfig:# CONFIG_BASE_FULL is not set
arch/riscv/configs/nommu_k210_sdcard_defconfig:# CONFIG_BASE_FULL is not set
arch/riscv/configs/nommu_virt_defconfig:# CONFIG_BASE_FULL is not set
arch/sh/configs/edosk7705_defconfig:# CONFIG_BASE_FULL is not set
arch/sh/configs/se7619_defconfig:# CONFIG_BASE_FULL is not set
arch/sh/configs/se7712_defconfig:# CONFIG_BASE_FULL is not set
arch/sh/configs/se7721_defconfig:# CONFIG_BASE_FULL is not set
arch/sh/configs/shmin_defconfig:# CONFIG_BASE_FULL is not set

Best Regards,
Petr

Re: [PATCH v4 3/3] printk: Remove redundant CONFIG_BASE_FULL

[Petr Mladek]

On Tue 2024-02-06 10:04:20, Petr Mladek wrote:
> On Tue 2024-02-06 01:13:33, Yoann Congal wrote:
> > CONFIG_BASE_FULL is equivalent to !CONFIG_BASE_SMALL and is enabled by
> > default: CONFIG_BASE_SMALL is the special case to take care of.
> > So, remove CONFIG_BASE_FULL and move the config choice to
> > CONFIG_BASE_SMALL (which defaults to 'n')
> > 
> > Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> 
> This might also require updatating the default config files which
> unset CONFIG_BASE_FULL. I mean:
> 
> $> git grep BASE_FULL arch/
> arch/arm/configs/collie_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/keystone_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/lpc18xx_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/moxart_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/mps2_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/omap1_defconfig:# CONFIG_BASE_FULL is not set
> arch/arm/configs/stm32_defconfig:# CONFIG_BASE_FULL is not set
> arch/microblaze/configs/mmu_defconfig:# CONFIG_BASE_FULL is not set
> arch/mips/configs/rs90_defconfig:# CONFIG_BASE_FULL is not set
> arch/powerpc/configs/adder875_defconfig:# CONFIG_BASE_FULL is not set
> arch/powerpc/configs/ep88xc_defconfig:# CONFIG_BASE_FULL is not set
> arch/powerpc/configs/mpc866_ads_defconfig:# CONFIG_BASE_FULL is not set
> arch/powerpc/configs/mpc885_ads_defconfig:# CONFIG_BASE_FULL is not set
> arch/powerpc/configs/tqm8xx_defconfig:# CONFIG_BASE_FULL is not set
> arch/riscv/configs/nommu_k210_defconfig:# CONFIG_BASE_FULL is not set
> arch/riscv/configs/nommu_k210_sdcard_defconfig:# CONFIG_BASE_FULL is not set
> arch/riscv/configs/nommu_virt_defconfig:# CONFIG_BASE_FULL is not set
> arch/sh/configs/edosk7705_defconfig:# CONFIG_BASE_FULL is not set
> arch/sh/configs/se7619_defconfig:# CONFIG_BASE_FULL is not set
> arch/sh/configs/se7712_defconfig:# CONFIG_BASE_FULL is not set
> arch/sh/configs/se7721_defconfig:# CONFIG_BASE_FULL is not set
> arch/sh/configs/shmin_defconfig:# CONFIG_BASE_FULL is not set

Ah, also we should drop:

tools/testing/selftests/wireguard/qemu/kernel.config:CONFIG_BASE_FULL=y

Best Regards,
Petr

Re: [PATCH v4 3/3] printk: Remove redundant CONFIG_BASE_FULL

[Masahiro Yamada]

On Tue, Feb 6, 2024 at 9:13 AM Yoann Congal <yoann.congal@smile.fr> wrote:
>
> CONFIG_BASE_FULL is equivalent to !CONFIG_BASE_SMALL and is enabled by
> default: CONFIG_BASE_SMALL is the special case to take care of.
> So, remove CONFIG_BASE_FULL and move the config choice to
> CONFIG_BASE_SMALL (which defaults to 'n')
>
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> ---
> v3->v4:
> * Split "switch CONFIG_BASE_SMALL to bool" and "Remove the redundant
>   config" (this patch) into two patches
> * keep CONFIG_BASE_SMALL instead of CONFIG_BASE_FULL
> ---
>  init/Kconfig | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index d4b16cad98502..4ecf2572d00ee 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1581,11 +1581,11 @@ config PCSPKR_PLATFORM
>           This option allows to disable the internal PC-Speaker
>           support, saving some memory.
>
> -config BASE_FULL
> -       default y
> -       bool "Enable full-sized data structures for core" if EXPERT
> +config BASE_SMALL
> +       default n



A nit.

Please drop the redundant 'default n' next time
(as it seems you will have a change to send v5)







> +       bool "Enable smaller-sized data structures for core" if EXPERT
>         help
> -         Disabling this option reduces the size of miscellaneous core
> +         Enabling this option reduces the size of miscellaneous core
>           kernel data structures. This saves memory on small machines,
>           but may reduce performance.
>
> @@ -1940,11 +1940,6 @@ config RT_MUTEXES
>         bool
>         default y if PREEMPT_RT
>
> -config BASE_SMALL
> -       bool
> -       default y if !BASE_FULL
> -       default n
> -
>  config MODULE_SIG_FORMAT
>         def_bool n
>         select SYSTEM_DATA_VERIFICATION
> --
> 2.39.2
>


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v4 2/3] printk: Change type of CONFIG_BASE_SMALL to bool

[Greg Kroah-Hartman]

On Tue, Feb 06, 2024 at 01:13:32AM +0100, Yoann Congal wrote:
> CONFIG_BASE_SMALL is currently a type int but is only used as a boolean.
> 
> So, change its type to bool and adapt all usages:
> CONFIG_BASE_SMALL == 0 becomes !IS_ENABLED(CONFIG_BASE_SMALL) and
> CONFIG_BASE_SMALL != 0 becomes  IS_ENABLED(CONFIG_BASE_SMALL).
> 
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> ---
> NB: This is preliminary work for the following patch removing
> CONFIG_BASE_FULL (now equivalent to !CONFIG_BASE_SMALL)

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v4 1/3] printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled

[Masahiro Yamada]

On Tue, Feb 6, 2024 at 9:13 AM Yoann Congal <yoann.congal@smile.fr> wrote:
>
> LOG_CPU_MAX_BUF_SHIFT default value depends on BASE_SMALL:
>   config LOG_CPU_MAX_BUF_SHIFT
>         default 12 if !BASE_SMALL
>         default 0 if BASE_SMALL
> But, BASE_SMALL is a config of type int and "!BASE_SMALL" is always
> evaluated to true whatever is the value of BASE_SMALL.
>
> This patch fixes this by using the correct conditional operator for int
> type : BASE_SMALL != 0.
>
> Note: This changes CONFIG_LOG_CPU_MAX_BUF_SHIFT=12 to
> CONFIG_LOG_CPU_MAX_BUF_SHIFT=0 for BASE_SMALL defconfigs, but that will
> not be a big impact due to this code in kernel/printk/printk.c:
>   /* by default this will only continue through for large > 64 CPUs */
>   if (cpu_extra <= __LOG_BUF_LEN / 2)
>           return;
> Systems using CONFIG_BASE_SMALL and having 64+ CPUs should be quite
> rare.
>
> John Ogness <john.ogness@linutronix.de> (printk reviewer) wrote:
> > For printk this will mean that BASE_SMALL systems were probably
> > previously allocating/using the dynamic ringbuffer and now they will
> > just continue to use the static ringbuffer. Which is fine and saves
> > memory (as it should).
>
> Petr Mladek <pmladek@suse.com> (printk maintainer) wrote:
> > More precisely, it allocated the buffer dynamically when the sum
> > of per-CPU-extra space exceeded half of the default static ring
> > buffer. This happened for systems with more than 64 CPUs with
> > the default config values.
>
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Closes: https://lore.kernel.org/all/CAMuHMdWm6u1wX7efZQf=2XUAHascps76YQac6rdnQGhc8nop_Q@mail.gmail.com/
> Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
> Closes: https://lore.kernel.org/all/f6856be8-54b7-0fa0-1d17-39632bf29ada@oracle.com/
> Fixes: 4e244c10eab3 ("kconfig: remove unneeded symbol_empty variable")



Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>





-- 
Best Regards
Masahiro Yamada

Re: [PATCH v4 2/3] printk: Change type of CONFIG_BASE_SMALL to bool

[Masahiro Yamada]

On Tue, Feb 6, 2024 at 9:13 AM Yoann Congal <yoann.congal@smile.fr> wrote:
>
> CONFIG_BASE_SMALL is currently a type int but is only used as a boolean.
>
> So, change its type to bool and adapt all usages:
> CONFIG_BASE_SMALL == 0 becomes !IS_ENABLED(CONFIG_BASE_SMALL) and
> CONFIG_BASE_SMALL != 0 becomes  IS_ENABLED(CONFIG_BASE_SMALL).
>
> Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
> ---
> NB: This is preliminary work for the following patch removing
> CONFIG_BASE_FULL (now equivalent to !CONFIG_BASE_SMALL)
>
> v3->v4:
> * Split "switch CONFIG_BASE_SMALL to bool" (this patch) and "Remove the redundant
>   config" into two patches
> * keep CONFIG_BASE_SMALL instead of CONFIG_BASE_FULL
> ---
>  arch/x86/include/asm/mpspec.h | 6 +++---
>  drivers/tty/vt/vc_screen.c    | 2 +-
>  include/linux/threads.h       | 4 ++--
>  include/linux/udp.h           | 2 +-
>  include/linux/xarray.h        | 2 +-
>  init/Kconfig                  | 8 ++++----
>  kernel/futex/core.c           | 2 +-
>  kernel/user.c                 | 2 +-
>  8 files changed, 14 insertions(+), 14 deletions(-)
>
> diff --git a/arch/x86/include/asm/mpspec.h b/arch/x86/include/asm/mpspec.h
> index 4b0f98a8d338d..c01d3105840cf 100644
> --- a/arch/x86/include/asm/mpspec.h
> +++ b/arch/x86/include/asm/mpspec.h
> @@ -15,10 +15,10 @@ extern int pic_mode;
>   * Summit or generic (i.e. installer) kernels need lots of bus entries.
>   * Maximum 256 PCI busses, plus 1 ISA bus in each of 4 cabinets.
>   */
> -#if CONFIG_BASE_SMALL == 0
> -# define MAX_MP_BUSSES         260
> -#else
> +#ifdef CONFIG_BASE_SMALL
>  # define MAX_MP_BUSSES         32
> +#else
> +# define MAX_MP_BUSSES         260
>  #endif
>
>  #define MAX_IRQ_SOURCES                256
> diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
> index 67e2cb7c96eec..da33c6c4691c0 100644
> --- a/drivers/tty/vt/vc_screen.c
> +++ b/drivers/tty/vt/vc_screen.c
> @@ -51,7 +51,7 @@
>  #include <asm/unaligned.h>
>
>  #define HEADER_SIZE    4u
> -#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
> +#define CON_BUF_SIZE (IS_ENABLED(CONFIG_BASE_SMALL) ? 256 : PAGE_SIZE)
>
>  /*
>   * Our minor space:
> diff --git a/include/linux/threads.h b/include/linux/threads.h
> index c34173e6c5f18..1674a471b0b4c 100644
> --- a/include/linux/threads.h
> +++ b/include/linux/threads.h
> @@ -25,13 +25,13 @@
>  /*
>   * This controls the default maximum pid allocated to a process
>   */
> -#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000)
> +#define PID_MAX_DEFAULT (IS_ENABLED(CONFIG_BASE_SMALL) ? 0x1000 : 0x8000)
>
>  /*
>   * A maximum of 4 million PIDs should be enough for a while.
>   * [NOTE: PID/TIDs are limited to 2^30 ~= 1 billion, see FUTEX_TID_MASK.]
>   */
> -#define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \
> +#define PID_MAX_LIMIT (IS_ENABLED(CONFIG_BASE_SMALL) ? PAGE_SIZE * 8 : \
>         (sizeof(long) > 4 ? 4 * 1024 * 1024 : PID_MAX_DEFAULT))
>
>  /*
> diff --git a/include/linux/udp.h b/include/linux/udp.h
> index d04188714dca1..b456417fb4515 100644
> --- a/include/linux/udp.h
> +++ b/include/linux/udp.h
> @@ -24,7 +24,7 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
>  }
>
>  #define UDP_HTABLE_SIZE_MIN_PERNET     128
> -#define UDP_HTABLE_SIZE_MIN            (CONFIG_BASE_SMALL ? 128 : 256)
> +#define UDP_HTABLE_SIZE_MIN            (IS_ENABLED(CONFIG_BASE_SMALL) ? 128 : 256)
>  #define UDP_HTABLE_SIZE_MAX            65536
>
>  static inline u32 udp_hashfn(const struct net *net, u32 num, u32 mask)
> diff --git a/include/linux/xarray.h b/include/linux/xarray.h
> index cb571dfcf4b16..3f81ee5f9fb9c 100644
> --- a/include/linux/xarray.h
> +++ b/include/linux/xarray.h
> @@ -1141,7 +1141,7 @@ static inline void xa_release(struct xarray *xa, unsigned long index)
>   * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
>   */
>  #ifndef XA_CHUNK_SHIFT
> -#define XA_CHUNK_SHIFT         (CONFIG_BASE_SMALL ? 4 : 6)
> +#define XA_CHUNK_SHIFT         (IS_ENABLED(CONFIG_BASE_SMALL) ? 4 : 6)
>  #endif
>  #define XA_CHUNK_SIZE          (1UL << XA_CHUNK_SHIFT)
>  #define XA_CHUNK_MASK          (XA_CHUNK_SIZE - 1)
> diff --git a/init/Kconfig b/init/Kconfig
> index d50ebd2a2ce42..d4b16cad98502 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -734,7 +734,7 @@ config LOG_CPU_MAX_BUF_SHIFT
>         int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)"
>         depends on SMP
>         range 0 21
> -       default 0 if BASE_SMALL != 0
> +       default 0 if BASE_SMALL
>         default 12
>         depends on PRINTK
>         help
> @@ -1941,9 +1941,9 @@ config RT_MUTEXES
>         default y if PREEMPT_RT
>
>  config BASE_SMALL
> -       int
> -       default 0 if BASE_FULL
> -       default 1 if !BASE_FULL
> +       bool
> +       default y if !BASE_FULL
> +       default n



The shortest form would be:


config BASE_SMALL
        def_bool !BASE_FULL



But, that is not a big deal, as this hunk will
be removed by 3/3.




Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>








-- 
Best Regards
Masahiro Yamada