linux-kernel - [RFC patch 14/41] latency_top: Remove the ULONG

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Message-Id: <20190410103644.853527514@linutronix.de>
Date:   Wed, 10 Apr 2019 12:28:08 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>
Subject: [RFC patch 14/41] 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>
---
 fs/proc/base.c      |    3 +--
 kernel/latencytop.c |   12 ++++++------
 2 files changed, 7 insertions(+), 8 deletions(-)

--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -489,10 +489,9 @@ static int lstats_show_proc(struct seq_f
 				   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');
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -120,8 +120,8 @@ account_global_scheduler_latency(struct
 				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 @@ void __sched
 				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 *
 				   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");