linux-kernel - [RFC patch 02/41] x86/stacktrace: Remove the pointless ULONG

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Message-Id: <20190410103643.750954603@linutronix.de>
Date:   Wed, 10 Apr 2019 12:27:56 +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 02/41] x86/stacktrace: Remove the pointless ULONG_MAX
 marker

Terminating the last trace entry with ULONG_MAX is a completely pointless
exercise and none of the consumers can rely on it because it's
inconsistently implemented across architectures. In fact quite some of the
callers remove the entry and adjust stack_trace.nr_entries afterwards.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/stacktrace.c |   14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -46,9 +46,6 @@ static void noinline __save_stack_trace(
 		if (!addr || save_stack_address(trace, addr, nosched))
 			break;
 	}
-
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }
 
 /*
@@ -97,7 +94,7 @@ static int __always_inline
 		if (regs) {
 			/* Success path for user tasks */
 			if (user_mode(regs))
-				goto success;
+				return 0;
 
 			/*
 			 * Kernel mode registers on the stack indicate an
@@ -132,10 +129,6 @@ static int __always_inline
 	if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
 		return -EINVAL;
 
-success:
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
-
 	return 0;
 }
 
@@ -221,9 +214,6 @@ void save_stack_trace_user(struct stack_
 	/*
 	 * Trace user stack if we are not a kernel thread
 	 */
-	if (current->mm) {
+	if (current->mm)
 		__save_stack_trace_user(trace);
-	}
-	if (trace->nr_entries < trace->max_entries)
-		trace->entries[trace->nr_entries++] = ULONG_MAX;
 }