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Groups > linux.kernel > #1448175

[PATCH 18/19] x86/dumpstack: print stack identifier on its own line

From Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups linux.kernel
Subject [PATCH 18/19] x86/dumpstack: print stack identifier on its own line
Date 2016-07-21 23:30 +0200
Message-ID <rXtHA-4Eb-23@gated-at.bofh.it> (permalink)
References <rXtHz-4Eb-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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show_trace_log_lvl() prints the stack id (e.g. "<IRQ>") without a
newline so that any stack address printed after it will appear on the
same line.  That causes the first stack address to be vertically
misaligned with the rest, making it visually cluttered and slightly
confusing:

  Call Trace:
   <IRQ> [<ffffffff814431c3>] dump_stack+0x86/0xc3
   [<ffffffff8100828b>] perf_callchain_kernel+0x14b/0x160
   [<ffffffff811e915f>] get_perf_callchain+0x15f/0x2b0
   ...
   <EOI> [<ffffffff8189c6c3>] ? _raw_spin_unlock_irq+0x33/0x60
   [<ffffffff810e1c84>] finish_task_switch+0xb4/0x250
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0

It will look worse once we start printing pt_regs registers found in the
middle of the stack:

  <IRQ> RIP: 0010:[<ffffffff8189c6c3>]  [<ffffffff8189c6c3>] _raw_spin_unlock_irq+0x33/0x60
  RSP: 0018:ffff88007876f720  EFLAGS: 00000206
  RAX: ffff8800786caa40 RBX: ffff88007d5da140 RCX: 0000000000000007
  ...

Improve readability by adding a newline to the stack name:

  Call Trace:
   <IRQ>
   [<ffffffff814431c3>] dump_stack+0x86/0xc3
   [<ffffffff8100828b>] perf_callchain_kernel+0x14b/0x160
   [<ffffffff811e915f>] get_perf_callchain+0x15f/0x2b0
   ...
   <EOI>
   [<ffffffff8189c6c3>] ? _raw_spin_unlock_irq+0x33/0x60
   [<ffffffff810e1c84>] finish_task_switch+0xb4/0x250
   [<ffffffff8106f7dc>] do_async_page_fault+0x2c/0xa0

Now that "continued" lines are no longer needed, we can also remove the
hack of using the empty string (aka KERN_CONT) and replace it with
KERN_DEFAULT.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/dumpstack.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 198dc9e..0eedb01 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -124,7 +124,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 
 		stack_type_str(stack_info.type, &str_begin, &str_end);
 		if (str_begin)
-			printk("%s <%s> ", log_lvl, str_begin);
+			printk("%s <%s>\n", log_lvl, str_begin);
 
 		/*
 		 * Scan the stack, printing any text addresses we find.  At the
@@ -176,7 +176,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		}
 
 		if (str_end)
-			printk("%s <%s> ", log_lvl, str_end);
+			printk("%s <%s>\n", log_lvl, str_end);
 	}
 }
 
@@ -193,12 +193,12 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 		bp = (unsigned long)get_frame_pointer(current, NULL);
 	}
 
-	show_stack_log_lvl(task, NULL, sp, "");
+	show_stack_log_lvl(task, NULL, sp, KERN_DEFAULT);
 }
 
 void show_stack_regs(struct pt_regs *regs)
 {
-	show_stack_log_lvl(NULL, regs, NULL, "");
+	show_stack_log_lvl(NULL, regs, NULL, KERN_DEFAULT);
 }
 
 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
-- 
2.7.4

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Thread

[PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 05/19] x86/dumpstack: fix function graph tracing stack dump reliability issues Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 04/19] x86/dumpstack: make printk_stack_address() more generally useful Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 18/19] x86/dumpstack: print stack identifier on its own line Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 13/19] x86/stacktrace: convert save_stack_trace_*() to the new unwinder Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:40 +0200
      Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-22 05:40 +0200
        Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Andy Lutomirski <luto@amacapital.net> - 2016-07-22 07:20 +0200
          Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-22 18:00 +0200
            Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Andy Lutomirski <luto@amacapital.net> - 2016-07-22 23:50 +0200
              Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 00:30 +0200
                Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Andy Lutomirski <luto@amacapital.net> - 2016-07-23 01:20 +0200
                Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Andy Lutomirski <luto@amacapital.net> - 2016-07-23 01:40 +0200
                Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 02:10 +0200
                Re: [PATCH 19/19] x86/dumpstack: print any pt_regs found on the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 01:40 +0200
  [PATCH 08/19] x86/dumpstack: don't disable preemption in show_stack_log_lvl() and dump_trace() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 14/19] oprofile/x86: convert x86_backtrace() to the new unwinder Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 06/19] x86/dumpstack: remove extra brackets around "EOE" Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Andy Lutomirski <luto@amacapital.net> - 2016-07-23 01:30 +0200
      Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Andy Lutomirski <luto@amacapital.net> - 2016-07-23 02:00 +0200
        Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 15:10 +0200
      Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 02:00 +0200
        Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Andy Lutomirski <luto@amacapital.net> - 2016-07-23 02:20 +0200
          Re: [PATCH 10/19] x86/dumpstack: add get_stack_info() interface Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 16:10 +0200
  [PATCH 01/19] x86/dumpstack: remove show_trace() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 01/19] x86/dumpstack: remove show_trace() Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:00 +0200
  [PATCH 12/19] perf/x86: convert perf_callchain_kernel() to the new unwinder Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 02/19] x86/dumpstack: add get_stack_pointer() and get_frame_pointer() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 02/19] x86/dumpstack: add get_stack_pointer() and get_frame_pointer() Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:00 +0200
  [PATCH 11/19] x86/dumptrace: add new unwind interface and implementations Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
  [PATCH 09/19] x86/dumpstack: simplify in_exception_stack() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 09/19] x86/dumpstack: simplify in_exception_stack() Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:10 +0200
  [PATCH 07/19] x86/dumpstack: add IRQ_USABLE_STACK_SIZE define Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-21 23:30 +0200
    Re: [PATCH 07/19] x86/dumpstack: add IRQ_USABLE_STACK_SIZE define Andy Lutomirski <luto@amacapital.net> - 2016-07-22 00:10 +0200
      Re: [PATCH 07/19] x86/dumpstack: add IRQ_USABLE_STACK_SIZE define Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-22 03:50 +0200
        Re: [PATCH 07/19] x86/dumpstack: add IRQ_USABLE_STACK_SIZE define Ingo Molnar <mingo@kernel.org> - 2016-07-22 10:30 +0200
  Re: [PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-23 02:30 +0200
    Re: [PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Andy Lutomirski <luto@amacapital.net> - 2016-07-23 02:40 +0200
      Re: [PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 07:40 +0200
        Re: [PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Linus Torvalds <torvalds@linux-foundation.org> - 2016-07-23 07:50 +0200
          Re: [PATCH 00/19] x86/dumpstack: rewrite x86 stack dump code Josh Poimboeuf <jpoimboe@redhat.com> - 2016-07-23 15:00 +0200

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