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Subject[tip:core/stacktrace] latency_top: Remove the ULONG_MAX stack trace hackery
Commit-ID:  accddc41b96915ab4e5d37796c6d17d70805999c
Gitweb: https://git.kernel.org/tip/accddc41b96915ab4e5d37796c6d17d70805999c
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 10 Apr 2019 12:28:08 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sun, 14 Apr 2019 19:58:31 +0200

latency_top: Remove the ULONG_MAX stack trace hackery

No architecture terminates the stack trace with ULONG_MAX anymore. The
consumer terminates on the first zero entry or at the number of entries, so
no functional change.

Remove the cruft.

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/20190410103644.853527514@linutronix.de

---
fs/proc/base.c | 3 +--
kernel/latencytop.c | 12 ++++++------
2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6a803a0b75df..5569f215fc54 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -489,10 +489,9 @@ static int lstats_show_proc(struct seq_file *m, void *v)
lr->count, lr->time, lr->max);
for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
unsigned long bt = lr->backtrace[q];
+
if (!bt)
break;
- if (bt == ULONG_MAX)
- break;
seq_printf(m, " %ps", (void *)bt);
}
seq_putc(m, '\n');
diff --git a/kernel/latencytop.c b/kernel/latencytop.c
index 96b4179cee6a..f5a90ab3c6b9 100644
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -120,8 +120,8 @@ account_global_scheduler_latency(struct task_struct *tsk,
break;
}

- /* 0 and ULONG_MAX entries mean end of backtrace: */
- if (record == 0 || record == ULONG_MAX)
+ /* 0 entry marks end of backtrace: */
+ if (!record)
break;
}
if (same) {
@@ -210,8 +210,8 @@ __account_scheduler_latency(struct task_struct *tsk, int usecs, int inter)
break;
}

- /* 0 and ULONG_MAX entries mean end of backtrace: */
- if (record == 0 || record == ULONG_MAX)
+ /* 0 entry is end of backtrace */
+ if (!record)
break;
}
if (same) {
@@ -252,10 +252,10 @@ static int lstats_show(struct seq_file *m, void *v)
lr->count, lr->time, lr->max);
for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
unsigned long bt = lr->backtrace[q];
+
if (!bt)
break;
- if (bt == ULONG_MAX)
- break;
+
seq_printf(m, " %ps", (void *)bt);
}
seq_puts(m, "\n");
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