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x86/dumpstack: Print stack identifier on its own line

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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>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/9bdd6dee2c74555d45500939fcc155997dc7889e.1476973742.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2016-10-20 11:34:42 -05:00 committed by Ingo Molnar
parent acb4608ad1
commit 79439d8e15
1 changed files with 4 additions and 4 deletions
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8
arch/x86/kernel/dumpstack.c
View file

@ -97,7 +97,7 @@ 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
@ -149,7 +149,7 @@ 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);
}
}
@ -164,12 +164,12 @@ void show_stack(struct task_struct *task, unsigned long *sp)
if (!sp && task == current)
sp = get_stack_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(current, regs, NULL, "");
show_stack_log_lvl(current, regs, NULL, KERN_DEFAULT);
}
static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;