From a358f40600b3b39ae3906b6118625b99c0aa7a34 Mon Sep 17 00:00:00 2001 From: Tanner Love Date: Mon, 28 Jun 2021 09:50:06 -0400 Subject: once: implement DO_ONCE_LITE for non-fast-path "do once" functionality Certain uses of "do once" functionality reside outside of fast path, and so do not require jump label patching via static keys, making existing DO_ONCE undesirable in such cases. Replace uses of __section(".data.once") with DO_ONCE_LITE(_IF)? This patch changes the return values of xfs_printk_once, printk_once, and printk_deferred_once. Before, they returned whether the print was performed, but now, they always return true. This is okay because the return values of the following macros are entirely ignored throughout the kernel: - xfs_printk_once - xfs_warn_once - xfs_notice_once - xfs_info_once - printk_once - pr_emerg_once - pr_alert_once - pr_crit_once - pr_err_once - pr_warn_once - pr_notice_once - pr_info_once - pr_devel_once - pr_debug_once - printk_deferred_once - orc_warn Changes v3: - Expand commit message to explain why changing return values of xfs_printk_once, printk_once, printk_deferred_once is benign v2: - Fix i386 build warnings Signed-off-by: Tanner Love Acked-by: Eric Dumazet Acked-by: Mahesh Bandewar Acked-by: Steven Rostedt (VMware) Signed-off-by: David S. Miller --- include/asm-generic/bug.h | 37 +++++++------------------------------ include/linux/once_lite.h | 24 ++++++++++++++++++++++++ include/linux/printk.h | 23 +++-------------------- 3 files changed, 34 insertions(+), 50 deletions(-) create mode 100644 include/linux/once_lite.h (limited to 'include') diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index b402494883b6..bafc51f483c4 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -4,6 +4,7 @@ #include #include +#include #define CUT_HERE "------------[ cut here ]------------\n" @@ -140,39 +141,15 @@ void __warn(const char *file, int line, void *caller, unsigned taint, }) #ifndef WARN_ON_ONCE -#define WARN_ON_ONCE(condition) ({ \ - static bool __section(".data.once") __warned; \ - int __ret_warn_once = !!(condition); \ - \ - if (unlikely(__ret_warn_once && !__warned)) { \ - __warned = true; \ - WARN_ON(1); \ - } \ - unlikely(__ret_warn_once); \ -}) +#define WARN_ON_ONCE(condition) \ + DO_ONCE_LITE_IF(condition, WARN_ON, 1) #endif -#define WARN_ONCE(condition, format...) ({ \ - static bool __section(".data.once") __warned; \ - int __ret_warn_once = !!(condition); \ - \ - if (unlikely(__ret_warn_once && !__warned)) { \ - __warned = true; \ - WARN(1, format); \ - } \ - unlikely(__ret_warn_once); \ -}) +#define WARN_ONCE(condition, format...) \ + DO_ONCE_LITE_IF(condition, WARN, 1, format) -#define WARN_TAINT_ONCE(condition, taint, format...) ({ \ - static bool __section(".data.once") __warned; \ - int __ret_warn_once = !!(condition); \ - \ - if (unlikely(__ret_warn_once && !__warned)) { \ - __warned = true; \ - WARN_TAINT(1, taint, format); \ - } \ - unlikely(__ret_warn_once); \ -}) +#define WARN_TAINT_ONCE(condition, taint, format...) \ + DO_ONCE_LITE_IF(condition, WARN_TAINT, 1, taint, format) #else /* !CONFIG_BUG */ #ifndef HAVE_ARCH_BUG diff --git a/include/linux/once_lite.h b/include/linux/once_lite.h new file mode 100644 index 000000000000..861e606b820f --- /dev/null +++ b/include/linux/once_lite.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_ONCE_LITE_H +#define _LINUX_ONCE_LITE_H + +#include + +/* Call a function once. Similar to DO_ONCE(), but does not use jump label + * patching via static keys. + */ +#define DO_ONCE_LITE(func, ...) \ + DO_ONCE_LITE_IF(true, func, ##__VA_ARGS__) +#define DO_ONCE_LITE_IF(condition, func, ...) \ + ({ \ + static bool __section(".data.once") __already_done; \ + bool __ret_do_once = !!(condition); \ + \ + if (unlikely(__ret_do_once && !__already_done)) { \ + __already_done = true; \ + func(__VA_ARGS__); \ + } \ + unlikely(__ret_do_once); \ + }) + +#endif /* _LINUX_ONCE_LITE_H */ diff --git a/include/linux/printk.h b/include/linux/printk.h index fe7eb2351610..885379a1c9a1 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -8,6 +8,7 @@ #include #include #include +#include extern const char linux_banner[]; extern const char linux_proc_banner[]; @@ -436,27 +437,9 @@ extern int kptr_restrict; #ifdef CONFIG_PRINTK #define printk_once(fmt, ...) \ -({ \ - static bool __section(".data.once") __print_once; \ - bool __ret_print_once = !__print_once; \ - \ - if (!__print_once) { \ - __print_once = true; \ - printk(fmt, ##__VA_ARGS__); \ - } \ - unlikely(__ret_print_once); \ -}) + DO_ONCE_LITE(printk, fmt, ##__VA_ARGS__) #define printk_deferred_once(fmt, ...) \ -({ \ - static bool __section(".data.once") __print_once; \ - bool __ret_print_once = !__print_once; \ - \ - if (!__print_once) { \ - __print_once = true; \ - printk_deferred(fmt, ##__VA_ARGS__); \ - } \ - unlikely(__ret_print_once); \ -}) + DO_ONCE_LITE(printk_deferred, fmt, ##__VA_ARGS__) #else #define printk_once(fmt, ...) \ no_printk(fmt, ##__VA_ARGS__) -- cgit v1.2.3