2020-02-16 07:44:53

by Amol Grover

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

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 <[email protected]>
---
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


Subject: [tip: timers/core] posix-timers: Pass lockdep expression to RCU lists

The following commit has been merged into the timers/core branch of tip:

Commit-ID: 9ea9c60fc23c35f865725ab390ca4308de919bb0
Gitweb: https://git.kernel.org/tip/9ea9c60fc23c35f865725ab390ca4308de919bb0
Author: Amol Grover <[email protected]>
AuthorDate: Sun, 16 Feb 2020 13:13:30 +05:30
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Mon, 17 Feb 2020 16:39:28 +01:00

posix-timers: Pass lockdep expression to RCU lists

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.

[ tglx: Removed the macro and put the condition right where it's used ]

Signed-off-by: Amol Grover <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/20200216074330.GA14025@workstation-portable

---
kernel/time/posix-timers.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index ff0eb30..07709ac 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -121,7 +121,8 @@ 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,
+ lockdep_is_held(&hash_lock)) {
if ((timer->it_signal == sig) && (timer->it_id == id))
return timer;
}

Subject: [tip: timers/core] posix-timers: Pass lockdep expression to RCU lists

The following commit has been merged into the timers/core branch of tip:

Commit-ID: 5fb1c2a5bbf79ccca8d17cf97f66085be5808027
Gitweb: https://git.kernel.org/tip/5fb1c2a5bbf79ccca8d17cf97f66085be5808027
Author: Amol Grover <[email protected]>
AuthorDate: Sun, 16 Feb 2020 13:13:30 +05:30
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Mon, 17 Feb 2020 20:12:19 +01:00

posix-timers: Pass lockdep expression to RCU lists

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.

[ tglx: Removed the macro and put the condition right where it's used ]

Signed-off-by: Amol Grover <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/20200216074330.GA14025@workstation-portable


---
kernel/time/posix-timers.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/time/posix-timers.c b/kernel/time/posix-timers.c
index ff0eb30..07709ac 100644
--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -121,7 +121,8 @@ 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,
+ lockdep_is_held(&hash_lock)) {
if ((timer->it_signal == sig) && (timer->it_id == id))
return timer;
}