From: Íñigo Huguet ihuguet@redhat.com
[ Upstream commit 67d93ffc0f3c47094750bde6d62e7c5765dc47a6 ]
vclocks were using spinlocks to protect access to its timecounter and cyclecounter. Access to timecounter/cyclecounter is backed by the same driver callbacks that are used for non-virtual PHCs, but the usage of the spinlock imposes a new limitation that didn't exist previously: now they're called in atomic context so they mustn't sleep.
Some drivers like sfc or ice may sleep on these callbacks, causing errors like "BUG: scheduling while atomic: ptp5/25223/0x00000002"
Fix it replacing the vclock's spinlock by a mutex. It fix the mentioned bug and it doesn't introduce longer delays.
I've tested synchronizing various different combinations of clocks: - vclock->sysclock - sysclock->vclock - vclock->vclock - hardware PHC in different NIC -> vclock - created 4 vclocks and launch 4 parallel phc2sys processes with lockdep enabled
In all cases, comparing the delays reported by phc2sys, they are in the same range of values than before applying the patch.
Link: https://lore.kernel.org/netdev/69d0ff33-bd32-6aa5-d36c-fbdc3c01337c@redhat.c... Fixes: 5d43f951b1ac ("ptp: add ptp virtual clock driver framework") Reported-by: Yalin Li yalli@redhat.com Suggested-by: Richard Cochran richardcochran@gmail.com Tested-by: Miroslav Lichvar mlichvar@redhat.com Signed-off-by: Íñigo Huguet ihuguet@redhat.com Acked-by: Richard Cochran richardcochran@gmail.com Link: https://lore.kernel.org/r/20230221130616.21837-1-ihuguet@redhat.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/ptp/ptp_private.h | 2 +- drivers/ptp/ptp_vclock.c | 44 +++++++++++++++++++-------------------- 2 files changed, 23 insertions(+), 23 deletions(-)
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h index 77918a2c67018..75f58fc468a71 100644 --- a/drivers/ptp/ptp_private.h +++ b/drivers/ptp/ptp_private.h @@ -66,7 +66,7 @@ struct ptp_vclock { struct hlist_node vclock_hash_node; struct cyclecounter cc; struct timecounter tc; - spinlock_t lock; /* protects tc/cc */ + struct mutex lock; /* protects tc/cc */ };
/* diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c index 1c0ed4805c0aa..dcf752c9e0450 100644 --- a/drivers/ptp/ptp_vclock.c +++ b/drivers/ptp/ptp_vclock.c @@ -43,16 +43,16 @@ static void ptp_vclock_hash_del(struct ptp_vclock *vclock) static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) { struct ptp_vclock *vclock = info_to_vclock(ptp); - unsigned long flags; s64 adj;
adj = (s64)scaled_ppm << PTP_VCLOCK_FADJ_SHIFT; adj = div_s64(adj, PTP_VCLOCK_FADJ_DENOMINATOR);
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; timecounter_read(&vclock->tc); vclock->cc.mult = PTP_VCLOCK_CC_MULT + adj; - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock);
return 0; } @@ -60,11 +60,11 @@ static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm) static int ptp_vclock_adjtime(struct ptp_clock_info *ptp, s64 delta) { struct ptp_vclock *vclock = info_to_vclock(ptp); - unsigned long flags;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; timecounter_adjtime(&vclock->tc, delta); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock);
return 0; } @@ -73,12 +73,12 @@ static int ptp_vclock_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts) { struct ptp_vclock *vclock = info_to_vclock(ptp); - unsigned long flags; u64 ns;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; ns = timecounter_read(&vclock->tc); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock); *ts = ns_to_timespec64(ns);
return 0; @@ -91,7 +91,6 @@ static int ptp_vclock_gettimex(struct ptp_clock_info *ptp, struct ptp_vclock *vclock = info_to_vclock(ptp); struct ptp_clock *pptp = vclock->pclock; struct timespec64 pts; - unsigned long flags; int err; u64 ns;
@@ -99,9 +98,10 @@ static int ptp_vclock_gettimex(struct ptp_clock_info *ptp, if (err) return err;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; ns = timecounter_cyc2time(&vclock->tc, timespec64_to_ns(&pts)); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock);
*ts = ns_to_timespec64(ns);
@@ -113,11 +113,11 @@ static int ptp_vclock_settime(struct ptp_clock_info *ptp, { struct ptp_vclock *vclock = info_to_vclock(ptp); u64 ns = timespec64_to_ns(ts); - unsigned long flags;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; timecounter_init(&vclock->tc, &vclock->cc, ns); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock);
return 0; } @@ -127,7 +127,6 @@ static int ptp_vclock_getcrosststamp(struct ptp_clock_info *ptp, { struct ptp_vclock *vclock = info_to_vclock(ptp); struct ptp_clock *pptp = vclock->pclock; - unsigned long flags; int err; u64 ns;
@@ -135,9 +134,10 @@ static int ptp_vclock_getcrosststamp(struct ptp_clock_info *ptp, if (err) return err;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + return -EINTR; ns = timecounter_cyc2time(&vclock->tc, ktime_to_ns(xtstamp->device)); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock);
xtstamp->device = ns_to_ktime(ns);
@@ -205,7 +205,7 @@ struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock)
INIT_HLIST_NODE(&vclock->vclock_hash_node);
- spin_lock_init(&vclock->lock); + mutex_init(&vclock->lock);
vclock->clock = ptp_clock_register(&vclock->info, &pclock->dev); if (IS_ERR_OR_NULL(vclock->clock)) { @@ -269,7 +269,6 @@ 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; - unsigned long flags; u64 ns; u64 vclock_ns = 0;
@@ -281,9 +280,10 @@ ktime_t ptp_convert_timestamp(const ktime_t *hwtstamp, int vclock_index) if (vclock->clock->index != vclock_index) continue;
- spin_lock_irqsave(&vclock->lock, flags); + if (mutex_lock_interruptible(&vclock->lock)) + break; vclock_ns = timecounter_cyc2time(&vclock->tc, ns); - spin_unlock_irqrestore(&vclock->lock, flags); + mutex_unlock(&vclock->lock); break; }