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locking: More accurate annotations for read_lock()

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On the archs using QUEUED_RWLOCKS, read_lock() is not always a recursive
read lock, actually it's only recursive if in_interrupt() is true. So
change the annotation accordingly to catch more deadlocks.

Note we used to treat read_lock() as pure recursive read locks in
lib/locking-seftest.c, and this is useful, especially for the lockdep
development selftest, so we keep this via a variable to force switching
lock annotation for read_lock().

Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200807074238.1632519-2-boqun.feng@gmail.com
This commit is contained in:
Boqun Feng 2020-08-07 15:42:20 +08:00 committed by Peter Zijlstra
parent 92b4e9f11a
commit e918188611
3 changed files with 47 additions and 1 deletions
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23
include/linux/lockdep.h
View File

@ -469,6 +469,20 @@ static inline void print_irqtrace_events(struct task_struct *curr)
}
#endif
/* Variable used to make lockdep treat read_lock() as recursive in selftests */
#ifdef CONFIG_DEBUG_LOCKING_API_SELFTESTS
extern unsigned int force_read_lock_recursive;
#else /* CONFIG_DEBUG_LOCKING_API_SELFTESTS */
#define force_read_lock_recursive 0
#endif /* CONFIG_DEBUG_LOCKING_API_SELFTESTS */
#ifdef CONFIG_LOCKDEP
extern bool read_lock_is_recursive(void);
#else /* CONFIG_LOCKDEP */
/* If !LOCKDEP, the value is meaningless */
#define read_lock_is_recursive() 0
#endif
/*
* For trivial one-depth nesting of a lock-class, the following
* global define can be used. (Subsystems with multiple levels
@ -490,7 +504,14 @@ static inline void print_irqtrace_events(struct task_struct *curr)
#define spin_release(l, i) lock_release(l, i)
#define rwlock_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define rwlock_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
#define rwlock_acquire_read(l, s, t, i) \
do { \
if (read_lock_is_recursive()) \
lock_acquire_shared_recursive(l, s, t, NULL, i); \
else \
lock_acquire_shared(l, s, t, NULL, i); \
} while (0)
#define rwlock_release(l, i) lock_release(l, i)
#define seqcount_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)

14
kernel/locking/lockdep.c
View File

@ -4967,6 +4967,20 @@ static bool lockdep_nmi(void)
return true;
}
/*
* read_lock() is recursive if:
* 1. We force lockdep think this way in selftests or
* 2. The implementation is not queued read/write lock or
* 3. The locker is at an in_interrupt() context.
*/
bool read_lock_is_recursive(void)
{
return force_read_lock_recursive ||
!IS_ENABLED(CONFIG_QUEUED_RWLOCKS) ||
in_interrupt();
}
EXPORT_SYMBOL_GPL(read_lock_is_recursive);
/*
* We are not always called with irqs disabled - do that here,
* and also avoid lockdep recursion:

11
lib/locking-selftest.c
View File

@ -28,6 +28,7 @@
* Change this to 1 if you want to see the failure printouts:
*/
static unsigned int debug_locks_verbose;
unsigned int force_read_lock_recursive;
static DEFINE_WD_CLASS(ww_lockdep);
@ -1978,6 +1979,11 @@ void locking_selftest(void)
return;
}
/*
* treats read_lock() as recursive read locks for testing purpose
*/
force_read_lock_recursive = 1;
/*
* Run the testsuite:
*/
@ -2073,6 +2079,11 @@ void locking_selftest(void)
ww_tests();
force_read_lock_recursive = 0;
/*
* queued_read_lock() specific test cases can be put here
*/
if (unexpected_testcase_failures) {
printk("-----------------------------------------------------------------\n");
debug_locks = 0;