From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 3 Jul 2006 07:24:37 +0000 (-0700)
Subject: [PATCH] lockdep: i386 remove multi entry backtraces
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f0a5c315eb266edc608a29971bb4ff1a3025c58f;p=linux-beck.git

[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: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/i386/Kconfig.debug b/arch/i386/Kconfig.debug
index c92191b1fb67..b20ddd04f3d8 100644
--- a/arch/i386/Kconfig.debug
+++ b/arch/i386/Kconfig.debug
@@ -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
 
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index e8c6086b2aa1..2bf8b55b91f8 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -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;
 }