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authorYoann Congal <yoann.congal@smile.fr>2024-05-05 11:03:41 +0300
committerPetr Mladek <pmladek@suse.com>2024-05-06 18:39:09 +0300
commit320bf43190514be5c00e11f47ec2160dd3993844 (patch)
tree3a322ecd11d87c256adfb9f8ffefa7e534b290d5 /init
parentb0546776ad3f332e215cebc0b063ba4351971cca (diff)
downloadlinux-320bf43190514be5c00e11f47ec2160dd3993844.tar.xz
printk: Fix LOG_CPU_MAX_BUF_SHIFT when BASE_SMALL is enabled
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. 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> Reviewed-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Yoann Congal <yoann.congal@smile.fr> Link: https://lore.kernel.org/r/20240505080343.1471198-2-yoann.congal@smile.fr Signed-off-by: Petr Mladek <pmladek@suse.com>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig4
1 files changed, 2 insertions, 2 deletions
diff --git a/init/Kconfig b/init/Kconfig
index f3ea5dea9c85..ff5b607c3218 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -743,8 +743,8 @@ 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