From 4285f2fcef8001ead0f1c9315ba50302cab68cda Mon Sep 17 00:00:00 2001 From: Thomas Gleixner 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 Acked-by: Peter Zijlstra (Intel) Cc: Josh Poimboeuf Cc: Andy Lutomirski Cc: Steven Rostedt Cc: Alexander Potapenko 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 795aa20..21ceae2 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 eec648a..c6e54ff 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]; -- 2.7.4