x86/stacktrace: Remove the pointless ULONG_MAX marker (c5c27a0a) · Commits · 戴 / test

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@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/20190410103643.750954603@linutronix.de

arch/x86/kernel/stacktrace.c

+2 −12

Original line number	Diff line number	Diff line
		@@ -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;
		}

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