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Commit f0a5c315 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] lockdep: i386 remove multi entry backtraces 

Remove CONFIG_STACK_BACKTRACE_COLS.

This feature didnt work out: instead of making kernel debugging more
efficient, it produces much harder to read stacktraces!  Check out this trace
for example:

  http://static.flickr.com/47/158326090_35d0129147_b_d.jpg



That backtrace could have been printed much nicer as a one-entry-per-line
thing, taking the same amount of screen real-estate.

Plus we remove 30 lines of kernel code as well.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c9ca1ba5

arch/i386/Kconfig.debug

+0 −9
Original line number Diff line number Diff line
@@ -31,15 +31,6 @@ config DEBUG_STACK_USAGE 


	  This option will slow down process creation somewhat.



config STACK_BACKTRACE_COLS

	int "Stack backtraces per line" if DEBUG_KERNEL

	range 1 3

	default 2

	help

	  Selects how many stack backtrace entries per line to display.



	  This can save screen space when displaying traces.



comment "Page alloc debug is incompatible with Software Suspend on i386"

	depends on DEBUG_KERNEL && SOFTWARE_SUSPEND

arch/i386/kernel/traps.c

+9 −30
Original line number Diff line number Diff line
@@ -115,28 +115,13 @@ static inline int valid_stack_ptr(struct thread_info *tinfo, void *p) 
}



/*

 * Print CONFIG_STACK_BACKTRACE_COLS address/symbol entries per line.

 * Print one address/symbol entries per line.

 */

static inline int print_addr_and_symbol(unsigned long addr, char *log_lvl,

					int printed)

static inline void print_addr_and_symbol(unsigned long addr, char *log_lvl)

{

	if (!printed)

		printk(log_lvl);



#if CONFIG_STACK_BACKTRACE_COLS == 1

	printk(" [<%08lx>] ", addr);

#else

	printk(" <%08lx> ", addr);

#endif

	print_symbol("%s", addr);



	printed = (printed + 1) % CONFIG_STACK_BACKTRACE_COLS;

	if (printed)

		printk(" ");

	else

		printk("\n");



	return printed;

	print_symbol("%s\n", addr);

}



static inline unsigned long print_context_stack(struct thread_info *tinfo,
@@ -144,12 +129,11 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo, 
				char *log_lvl)

{

	unsigned long addr;

	int printed = 0; /* nr of entries already printed on current line */



#ifdef	CONFIG_FRAME_POINTER

	while (valid_stack_ptr(tinfo, (void *)ebp)) {

		addr = *(unsigned long *)(ebp + 4);

		printed = print_addr_and_symbol(addr, log_lvl, printed);

		print_addr_and_symbol(addr, log_lvl);

		/*

		 * break out of recursive entries (such as

		 * end_of_stack_stop_unwind_function):
@@ -162,28 +146,23 @@ static inline unsigned long print_context_stack(struct thread_info *tinfo, 
	while (valid_stack_ptr(tinfo, stack)) {

		addr = *stack++;

		if (__kernel_text_address(addr))

			printed = print_addr_and_symbol(addr, log_lvl, printed);

			print_addr_and_symbol(addr, log_lvl);

	}

#endif

	if (printed)

		printk("\n");



	return ebp;

}



static asmlinkage int show_trace_unwind(struct unwind_frame_info *info, void *log_lvl)

static asmlinkage int

show_trace_unwind(struct unwind_frame_info *info, void *log_lvl)

{

	int n = 0;

	int printed = 0; /* nr of entries already printed on current line */



	while (unwind(info) == 0 && UNW_PC(info)) {

		++n;

		printed = print_addr_and_symbol(UNW_PC(info), log_lvl, printed);

		n++;

		print_addr_and_symbol(UNW_PC(info), log_lvl);

		if (arch_unw_user_mode(info))

			break;

	}

	if (printed)

		printk("\n");

	return n;

}