[PATCH RESEND] kernel: time: posix-timers: Pass lockdep expression to RCU lists

From: Amol Grover
Date: Sun Feb 16 2020 - 02:44:03 EST


head is traversed using hlist_for_each_entry_rcu outside an
RCU read-side critical section but under the protection
of hash_lock.

Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists.

Add macro for the corresponding lockdep expression.

Signed-off-by: Amol Grover <frextrite@xxxxxxxxx>
---
kernel/time/posix-timers.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index 0ec5b7a1d769..2ccce00af177 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -50,6 +50,8 @@ static struct kmem_cache *posix_timers_cache;

static DEFINE_HASHTABLE(posix_timers_hashtable, 9);
static DEFINE_SPINLOCK(hash_lock);
+#define hash_lock_held() \
+ lockdep_is_held(&hash_lock)

static const struct k_clock * const posix_clocks[];
static const struct k_clock *clockid_to_kclock(const clockid_t id);
@@ -120,7 +122,7 @@ static struct k_itimer *__posix_timers_find(struct hlist_head *head,
{
struct k_itimer *timer;

- hlist_for_each_entry_rcu(timer, head, t_hash) {
+ hlist_for_each_entry_rcu(timer, head, t_hash, hash_lock_held()) {
if ((timer->it_signal == sig) && (timer->it_id == id))
return timer;
}
--
2.24.1