linux-kernel - [tip:core/stacktrace] x86/stacktrace: Remove the pointless ULONG

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Message-ID: <tip-c5c27a0a583844c69a433039e4fd6396ba23551b@git.kernel.org>
Date:   Sun, 14 Apr 2019 13:34:47 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, luto@...nel.org, hpa@...or.com,
        mingo@...nel.org, rostedt@...dmis.org, peterz@...radead.org,
        glider@...gle.com, jpoimboe@...hat.com,
        linux-kernel@...r.kernel.org
Subject: [tip:core/stacktrace] x86/stacktrace: Remove the pointless
 ULONG_MAX marker

Commit-ID:  c5c27a0a583844c69a433039e4fd6396ba23551b
Gitweb:     https://git.kernel.org/tip/c5c27a0a583844c69a433039e4fd6396ba23551b
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Wed, 10 Apr 2019 12:27:56 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sun, 14 Apr 2019 19:58:27 +0200

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>
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/20190410103643.750954603@linutronix.de

---
 arch/x86/kernel/stacktrace.c | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 5c2d71a1dc06..b2f706f1e0b7 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -46,9 +46,6 @@ static void noinline __save_stack_trace(struct stack_trace *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 @@ __save_stack_trace_reliable(struct stack_trace *trace,
 		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 @@ __save_stack_trace_reliable(struct stack_trace *trace,
 	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 *trace)
 	/*
 	 * 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;
 }