From 4285f2fcef8001ead0f1c9315ba50302cab68cda Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 10 Apr 2019 12:28:10 +0200
Subject: [PATCH] tracing: Remove the ULONG_MAX stack trace hackery
No architecture terminates the stack trace with ULONG_MAX anymore. As the
code checks the number of entries stored anyway there is no point in
keeping all that ULONG_MAX magic around.
The histogram code zeroes the storage before saving the stack, so if the
trace is shorter than the maximum number of entries it can terminate the
print loop if a zero entry is detected.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Potapenko <glider@google.com>
Link: https://lkml.kernel.org/r/20190410103645.048761764@linutronix.de
---
kernel/trace/trace_events_hist.c | 2 +-
kernel/trace/trace_stack.c | 20 +++++---------------
2 files changed, 6 insertions(+), 16 deletions(-)
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 795aa20383773..21ceae299f7eb 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -5246,7 +5246,7 @@ static void hist_trigger_stacktrace_print(struct seq_file *m,
unsigned int i;
for (i = 0; i < max_entries; i++) {
- if (stacktrace_entries[i] == ULONG_MAX)
+ if (!stacktrace_entries[i])
return;
seq_printf(m, "%*c", 1 + spaces, ' ');
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index eec648a0d673b..c6e54ff25caea 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -18,8 +18,7 @@
#include "trace.h"
-static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
- { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
+static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES + 1];
unsigned stack_trace_index[STACK_TRACE_ENTRIES];
/*
@@ -52,10 +51,7 @@ void stack_trace_print(void)
stack_trace_max.nr_entries);
for (i = 0; i < stack_trace_max.nr_entries; i++) {
- if (stack_dump_trace[i] == ULONG_MAX)
- break;
- if (i+1 == stack_trace_max.nr_entries ||
- stack_dump_trace[i+1] == ULONG_MAX)
+ if (i + 1 == stack_trace_max.nr_entries)
size = stack_trace_index[i];
else
size = stack_trace_index[i] - stack_trace_index[i+1];
@@ -150,8 +146,6 @@ check_stack(unsigned long ip, unsigned long *stack)
p = start;
for (; p < top && i < stack_trace_max.nr_entries; p++) {
- if (stack_dump_trace[i] == ULONG_MAX)
- break;
/*
* The READ_ONCE_NOCHECK is used to let KASAN know that
* this is not a stack-out-of-bounds error.
@@ -183,8 +177,6 @@ check_stack(unsigned long ip, unsigned long *stack)
}
stack_trace_max.nr_entries = x;
- for (; x < i; x++)
- stack_dump_trace[x] = ULONG_MAX;
if (task_stack_end_corrupted(current)) {
stack_trace_print();
@@ -286,7 +278,7 @@ __next(struct seq_file *m, loff_t *pos)
{
long n = *pos - 1;
- if (n >= stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX)
+ if (n >= stack_trace_max.nr_entries)
return NULL;
m->private = (void *)n;
@@ -360,12 +352,10 @@ static int t_show(struct seq_file *m, void *v)
i = *(long *)v;
- if (i >= stack_trace_max.nr_entries ||
- stack_dump_trace[i] == ULONG_MAX)
+ if (i >= stack_trace_max.nr_entries)
return 0;
- if (i+1 == stack_trace_max.nr_entries ||
- stack_dump_trace[i+1] == ULONG_MAX)
+ if (i + 1 == stack_trace_max.nr_entries)
size = stack_trace_index[i];
else
size = stack_trace_index[i] - stack_trace_index[i+1];
--
GitLab