Commit 49faa777 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

locking/lockdep: Improve noinstr vs errors 



Better handle the failure paths.

  vmlinux.o: warning: objtool: debug_locks_off()+0x23: call to console_verbose() leaves .noinstr.text section
  vmlinux.o: warning: objtool: debug_locks_off()+0x19: call to __kasan_check_write() leaves .noinstr.text section

  debug_locks_off+0x19/0x40:
  instrument_atomic_write at include/linux/instrumented.h:86
  (inlined by) __debug_locks_off at include/linux/debug_locks.h:17
  (inlined by) debug_locks_off at lib/debug_locks.c:41

Fixes: 6eebad1a ("lockdep: __always_inline more for noinstr")
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210621120120.784404944@infradead.org
parent 1f008d46

include/linux/debug_locks.h

+2 −0
Original line number Diff line number Diff line
@@ -27,8 +27,10 @@ extern int debug_locks_off(void); 
	int __ret = 0;							\

									\

	if (!oops_in_progress && unlikely(c)) {				\

		instrumentation_begin();				\

		if (debug_locks_off() && !debug_locks_silent)		\

			WARN(1, "DEBUG_LOCKS_WARN_ON(%s)", #c);		\

		instrumentation_end();					\

		__ret = 1;						\

	}								\

	__ret;								\

kernel/locking/lockdep.c

+3 −1
Original line number Diff line number Diff line
@@ -843,7 +843,7 @@ static int count_matching_names(struct lock_class *new_class) 
}



/* used from NMI context -- must be lockless */

static __always_inline struct lock_class *

static noinstr struct lock_class *

look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass)

{

	struct lockdep_subclass_key *key;
@@ -851,12 +851,14 @@ look_up_lock_class(const struct lockdep_map *lock, unsigned int subclass) 
	struct lock_class *class;



	if (unlikely(subclass >= MAX_LOCKDEP_SUBCLASSES)) {

		instrumentation_begin();

		debug_locks_off();

		printk(KERN_ERR

			"BUG: looking up invalid subclass: %u\n", subclass);

		printk(KERN_ERR

			"turning off the locking correctness validator.\n");

		dump_stack();

		instrumentation_end();

		return NULL;

	}

lib/debug_locks.c

+1 −1
Original line number Diff line number Diff line
@@ -36,7 +36,7 @@ EXPORT_SYMBOL_GPL(debug_locks_silent); 
/*

 * Generic 'turn off all lock debugging' function:

 */

noinstr int debug_locks_off(void)

int debug_locks_off(void)

{

	if (debug_locks && __debug_locks_off()) {

		if (!debug_locks_silent) {