linux-kernel - [tip:core/stacktrace] latency_top: Remove the ULONG

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Message-ID: <tip-accddc41b96915ab4e5d37796c6d17d70805999c@git.kernel.org>
Date:   Sun, 14 Apr 2019 13:42:54 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rostedt@...dmis.org, peterz@...radead.org, jpoimboe@...hat.com,
        luto@...nel.org, tglx@...utronix.de, mingo@...nel.org,
        glider@...gle.com, linux-kernel@...r.kernel.org, hpa@...or.com
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@...utronix.de>
AuthorDate: Wed, 10 Apr 2019 12:28:08 +0200
Committer:  Thomas Gleixner <tglx@...utronix.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@...utronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Alexander Potapenko <glider@...gle.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");