debug: move WARN_ON() out of line (79b4cc5e) · Commits · 戴 / test

A quick grep shows that there are currently 1145 instances of WARN_ON in the kernel. Currently, WARN_ON is pretty much entirely inlined, which makes it hard to enhance it without growing the size of the kernel (and getting Andrew unhappy). This patch build on top of Olof's patch that introduces __WARN, and places the slowpath out of line. It also uses Ingo's suggestion to not use __FUNCTION__ but to use kallsyms to do the lookup; this saves a ton of extra space since gcc doesn't need to store the function string twice now: 3936367 833603 624736 5394706 525112 vmlinux.before 3917508 833603 624736 5375847 520767 vmlinux-slowpath 15Kb savings... Signed-off-by:

Arjan van de Ven <arjan@linux.intel.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Olof Johansson <olof@lixom.net> Acked-by:

Matt Meckall <mpm@selenic.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

include/asm-generic/bug.h

+5 −5

Original line number	Diff line number	Diff line
		@@ -32,11 +32,11 @@ struct bug_entry {
		#endif

		#ifndef __WARN
		#define __WARN() do { \
		printk("WARNING: at %s:%d %s()\n", __FILE__, \
		__LINE__, __FUNCTION__); \
		dump_stack(); \
		} while (0)
		#ifndef __ASSEMBLY__
		extern void warn_on_slowpath(const char *file, const int line);
		#define WANT_WARN_ON_SLOWPATH
		#endif
		#define __WARN() warn_on_slowpath(__FILE__, __LINE__)
		#endif

		#ifndef WARN_ON

kernel/panic.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@
		#include <linux/kexec.h>
		#include <linux/debug_locks.h>
		#include <linux/random.h>
		#include <linux/kallsyms.h>

		int panic_on_oops;
		int tainted;
		@@ -292,6 +293,20 @@ void oops_exit(void)
		(unsigned long long)oops_id);
		}

		#ifdef WANT_WARN_ON_SLOWPATH
		void warn_on_slowpath(const char *file, int line)
		{
		char function[KSYM_SYMBOL_LEN];
		unsigned long caller = (unsigned long) __builtin_return_address(0);

		sprint_symbol(function, caller);
		printk(KERN_WARNING "WARNING: at %s:%d %s()\n", file,
		line, function);
		dump_stack();
		}
		EXPORT_SYMBOL(warn_on_slowpath);
		#endif

		#ifdef CONFIG_CC_STACKPROTECTOR
		/*
		* Called when gcc's -fstack-protector feature is used, and

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