diff options
| author | Kurt Kanzenbach <kurt@linutronix.de> | 2026-05-29 19:11:47 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-06-03 18:58:54 -0700 |
| commit | 672bd0519e27c357c43b7f8c0d653fce3817d06e (patch) | |
| tree | 1846fe3f96a8d59ad4a3e32cb8e5abf00458ea96 /drivers | |
| parent | d3915a1f5a4bc0ac911032903c3c6ab8df9fcc7c (diff) | |
ptp: vclock: Switch from RCU to SRCU
The usage of PTP vClocks leads immediately to the following issues with
ptp4l with LOCKDEP and DEBUG_ATOMIC_SLEEP enabled: "BUG: sleeping function
called from invalid context".
ptp_convert_timestamp() acquires a mutex_t within a RCU read section. This
is illegal, because acquiring a mutex_t can result in voluntary scheduling
request which is not allowed within a RCU read section.
Replace the RCU usage with SRCU where sleeping is allowed.
Reported-by: Florian Zeitz <florian.zeitz@schettke.com>
Closes: https://lore.kernel.org/all/00a8cce8-410e-4038-98af-49be6d93d7bd@schettke.com/
Fixes: 67d93ffc0f3c ("ptp: vclock: use mutex to fix "sleep on atomic" bug")
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20260529-vclock_rcu-v2-1-02a5531fab92@linutronix.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/ptp/ptp_vclock.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c index 915a4f6defc9..84cb527f59cc 100644 --- a/drivers/ptp/ptp_vclock.c +++ b/drivers/ptp/ptp_vclock.c @@ -19,6 +19,8 @@ static DEFINE_SPINLOCK(vclock_hash_lock); static DEFINE_READ_MOSTLY_HASHTABLE(vclock_hash, 8); +DEFINE_STATIC_SRCU(vclock_srcu); + static void ptp_vclock_hash_add(struct ptp_vclock *vclock) { spin_lock(&vclock_hash_lock); @@ -37,7 +39,7 @@ static void ptp_vclock_hash_del(struct ptp_vclock *vclock) spin_unlock(&vclock_hash_lock); - synchronize_rcu(); + synchronize_srcu(&vclock_srcu); } static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) @@ -276,14 +278,16 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index) { unsigned int hash = vclock_index % HASH_SIZE(vclock_hash); struct ptp_vclock *vclock; - u64 ns; u64 vclock_ns = 0; + int srcu_idx; + u64 ns; ns = ktime_to_ns(*hwtstamp); - rcu_read_lock(); + srcu_idx = srcu_read_lock(&vclock_srcu); - hlist_for_each_entry_rcu(vclock, &vclock_hash[hash], vclock_hash_node) { + hlist_for_each_entry_srcu(vclock, &vclock_hash[hash], vclock_hash_node, + srcu_read_lock_held(&vclock_srcu)) { if (vclock->clock->index != vclock_index) continue; @@ -294,7 +298,7 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index) break; } - rcu_read_unlock(); + srcu_read_unlock(&vclock_srcu, srcu_idx); return ns_to_ktime(vclock_ns); } |