stacktrace: Constify 'entries' arguments

Make it clear to humans and to the compiler that the stack trace
('entries') arguments are not modified.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190722182443.216015-3-bvanassche@acm.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/stacktrace.h

@@ -9,9 +9,9 @@ struct task_struct;
 struct pt_regs;
 
 #ifdef CONFIG_STACKTRACE
-void stack_trace_print(unsigned long *trace, unsigned int nr_entries,
+void stack_trace_print(const unsigned long *trace, unsigned int nr_entries,
 		       int spaces);
-int stack_trace_snprint(char *buf, size_t size, unsigned long *entries,
+int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
 			unsigned int nr_entries, int spaces);
 unsigned int stack_trace_save(unsigned long *store, unsigned int size,
 			      unsigned int skipnr);

kernel/stacktrace.c

@@ -20,7 +20,7 @@
  * @nr_entries:	Number of entries in the storage array
  * @spaces:	Number of leading spaces to print
  */
-void stack_trace_print(unsigned long *entries, unsigned int nr_entries,
+void stack_trace_print(const unsigned long *entries, unsigned int nr_entries,
 		       int spaces)
 {
 	unsigned int i;
@@ -43,7 +43,7 @@ EXPORT_SYMBOL_GPL(stack_trace_print);
  *
  * Return: Number of bytes printed.
  */
-int stack_trace_snprint(char *buf, size_t size, unsigned long *entries,
+int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
 			unsigned int nr_entries, int spaces)
 {
 	unsigned int generated, i, total = 0;