From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761106AbdJQWP2 (ORCPT ); Tue, 17 Oct 2017 18:15:28 -0400 Received: from mga04.intel.com ([192.55.52.120]:61369 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751757AbdJQWO7 (ORCPT ); Tue, 17 Oct 2017 18:14:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.43,392,1503385200"; d="scan'208";a="324396876" From: Andi Kleen To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, Andi Kleen Subject: [PATCH v2] Support resetting WARN*_ONCE Date: Tue, 17 Oct 2017 15:14:55 -0700 Message-Id: <20171017221455.6740-1-andi@firstfloor.org> X-Mailer: git-send-email 2.13.6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andi Kleen I like _ONCE warnings because it's guaranteed that they don't flood the log. During testing I find it useful to reset the state of the once warnings, so that I can rerun tests and see if they trigger again, or can guarantee that a test run always hits the same warnings. This patch adds a debugfs interface to reset all the _ONCE warnings so that they appear again: echo 1 > /sys/kernel/debug/clear_warn_once This is implemented by putting all the warning booleans into a special section, and clearing it. v2: Document interface. Include asm/sections.h (Andrew Morton) Signed-off-by: Andi Kleen --- Documentation/clearing-warn-once.txt | 7 +++++++ include/asm-generic/bug.h | 6 +++--- include/asm-generic/sections.h | 1 + include/asm-generic/vmlinux.lds.h | 3 +++ kernel/panic.c | 28 ++++++++++++++++++++++++++++ 5 files changed, 42 insertions(+), 3 deletions(-) create mode 100644 Documentation/clearing-warn-once.txt diff --git a/Documentation/clearing-warn-once.txt b/Documentation/clearing-warn-once.txt new file mode 100644 index 000000000000..5b1f5d547be1 --- /dev/null +++ b/Documentation/clearing-warn-once.txt @@ -0,0 +1,7 @@ + +WARN_ONCE / WARN_ON_ONCE only print a warning once. + +echo 1 > /sys/kernel/debug/clear_warn_once + +clears the state and allows the warnings to print once again. +This can be useful after test suite runs to reproduce problems. diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index 87191357d303..68c2f08b7914 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -129,7 +129,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, #ifndef WARN_ON_ONCE #define WARN_ON_ONCE(condition) ({ \ - static bool __section(.data.unlikely) __warned; \ + static bool __section(.data.once) __warned; \ int __ret_warn_once = !!(condition); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ @@ -141,7 +141,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, #endif #define WARN_ONCE(condition, format...) ({ \ - static bool __section(.data.unlikely) __warned; \ + static bool __section(.data.once) __warned; \ int __ret_warn_once = !!(condition); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ @@ -152,7 +152,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint, }) #define WARN_TAINT_ONCE(condition, taint, format...) ({ \ - static bool __section(.data.unlikely) __warned; \ + static bool __section(.data.once) __warned; \ int __ret_warn_once = !!(condition); \ \ if (unlikely(__ret_warn_once && !__warned)) { \ diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h index e5da44eddd2f..611c01bc5d21 100644 --- a/include/asm-generic/sections.h +++ b/include/asm-generic/sections.h @@ -43,6 +43,7 @@ extern char __entry_text_start[], __entry_text_end[]; extern char __start_rodata[], __end_rodata[]; extern char __irqentry_text_start[], __irqentry_text_end[]; extern char __softirqentry_text_start[], __softirqentry_text_end[]; +extern char __start_once[], __end_once[]; /* Start and end of .ctors section - used for constructor calls. */ extern char __ctors_start[], __ctors_end[]; diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 8acfc1e099e1..ac511e24ea4a 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -223,6 +223,9 @@ MEM_KEEP(init.data) \ MEM_KEEP(exit.data) \ *(.data.unlikely) \ + VMLINUX_SYMBOL(__start_once) = .; \ + *(.data.once) \ + VMLINUX_SYMBOL(__end_once) = .; \ STRUCT_ALIGN(); \ *(__tracepoints) \ /* implement dynamic printk debug */ \ diff --git a/kernel/panic.c b/kernel/panic.c index bdd18afa19a4..49dbdb231a77 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -27,6 +27,8 @@ #include #include #include +#include +#include #define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 @@ -587,6 +589,32 @@ void warn_slowpath_null(const char *file, int line) EXPORT_SYMBOL(warn_slowpath_null); #endif +#ifdef CONFIG_BUG + +/* Support resetting WARN*_ONCE state */ + +static int clear_warn_once_set(void *data, u64 val) +{ + memset(__start_once, 0, __end_once - __start_once); + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(clear_warn_once_fops, + NULL, + clear_warn_once_set, + "%lld\n"); + +static __init int register_warn_debugfs(void) +{ + /* Don't care about failure */ + debugfs_create_file("clear_warn_once", 0644, NULL, + NULL, &clear_warn_once_fops); + return 0; +} + +__initcall(register_warn_debugfs); +#endif + #ifdef CONFIG_CC_STACKPROTECTOR /* -- 2.13.6