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net/mlx5e: Fix soft lockup when HW Timestamping is enabled 

Readers/Writers lock for SW timecounter was acquired without disabling
interrupts on local CPU.

The problematic scenario:
* HW timestamping is enabled
* Timestamp overflow periodic service task is running on local CPU and
  holding write_lock for SW timecounter
* Completion arrives, triggers interrupt for local CPU.
  Interrupt routine calls napi_schedule(), which triggers rx/tx
  skb process.
  An attempt to read SW timecounter using read_lock is done, which is
  already locked by a writer on the same CPU and cause soft lockup.

Add irqsave/irqrestore for when using the readers/writers lock for
writing.

Fixes: ef9814deaf ('net/mlx5e: Add HW timestamping (TS) support')
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eran Ben Elisha 2016-02-29 21:17:11 +02:00 committed by David S. Miller
parent ab0394fe2c
commit 0ad9b20415
1 changed files with 15 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
drivers/net/ethernet/mellanox/mlx5/core/en_clock.c
View File

@ -62,10 +62,11 @@ static void mlx5e_timestamp_overflow(struct work_struct *work)
struct delayed_work *dwork = to_delayed_work(work);
struct mlx5e_tstamp *tstamp = container_of(dwork, struct mlx5e_tstamp,
overflow_work);
unsigned long flags;
write_lock(&tstamp->lock);
write_lock_irqsave(&tstamp->lock, flags);
timecounter_read(&tstamp->clock);
write_unlock(&tstamp->lock);
write_unlock_irqrestore(&tstamp->lock, flags);
schedule_delayed_work(&tstamp->overflow_work, tstamp->overflow_period);
}
@ -136,10 +137,11 @@ static int mlx5e_ptp_settime(struct ptp_clock_info *ptp,
struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
ptp_info);
u64 ns = timespec64_to_ns(ts);
unsigned long flags;
write_lock(&tstamp->lock);
write_lock_irqsave(&tstamp->lock, flags);
timecounter_init(&tstamp->clock, &tstamp->cycles, ns);
write_unlock(&tstamp->lock);
write_unlock_irqrestore(&tstamp->lock, flags);
return 0;
}
@ -150,10 +152,11 @@ static int mlx5e_ptp_gettime(struct ptp_clock_info *ptp,
struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
ptp_info);
u64 ns;
unsigned long flags;
write_lock(&tstamp->lock);
write_lock_irqsave(&tstamp->lock, flags);
ns = timecounter_read(&tstamp->clock);
write_unlock(&tstamp->lock);
write_unlock_irqrestore(&tstamp->lock, flags);
*ts = ns_to_timespec64(ns);
@ -164,10 +167,11 @@ static int mlx5e_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
ptp_info);
unsigned long flags;
write_lock(&tstamp->lock);
write_lock_irqsave(&tstamp->lock, flags);
timecounter_adjtime(&tstamp->clock, delta);
write_unlock(&tstamp->lock);
write_unlock_irqrestore(&tstamp->lock, flags);
return 0;
}
@ -176,6 +180,7 @@ static int mlx5e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 delta)
{
u64 adj;
u32 diff;
unsigned long flags;
int neg_adj = 0;
struct mlx5e_tstamp *tstamp = container_of(ptp, struct mlx5e_tstamp,
ptp_info);
@ -189,11 +194,11 @@ static int mlx5e_ptp_adjfreq(struct ptp_clock_info *ptp, s32 delta)
adj *= delta;
diff = div_u64(adj, 1000000000ULL);
write_lock(&tstamp->lock);
write_lock_irqsave(&tstamp->lock, flags);
timecounter_read(&tstamp->clock);
tstamp->cycles.mult = neg_adj ? tstamp->nominal_c_mult - diff :
tstamp->nominal_c_mult + diff;
write_unlock(&tstamp->lock);
write_unlock_irqrestore(&tstamp->lock, flags);
return 0;
}