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net/mlx4_en: fix overflow in mlx4_en_init_timestamp()

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The cited commit makes a great job of finding optimal shift/multiplier
values assuming a 10 seconds wrap around, but forgot to change the
overflow_period computation.

It overflows in cyclecounter_cyc2ns(), and the final result is 804 ms,
which is silly.

Lets simply use 5 seconds, no need to recompute this, given how it is
supposed to work.

Later, we will use a timer instead of a work queue, since the new RX
allocation schem will no longer need mlx4_en_recover_from_oom() and the
service_task firing every 250 ms.

Fixes: 31c128b66e ("net/mlx4_en: Choose time-stamping shift value according to HW frequency")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Eugenia Emantayev <eugenia@mellanox.com>
Reviewed-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-02-23 15:22:43 -08:00 committed by David S. Miller
parent 8b1bb92bb6
commit 47d3a07528
2 changed files with 8 additions and 11 deletions
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18
drivers/net/ethernet/mellanox/mlx4/en_clock.c
View File

@ -89,10 +89,17 @@ void mlx4_en_remove_timestamp(struct mlx4_en_dev *mdev)
}
}
#define MLX4_EN_WRAP_AROUND_SEC 10UL
/* By scheduling the overflow check every 5 seconds, we have a reasonably
* good chance we wont miss a wrap around.
* TOTO: Use a timer instead of a work queue to increase the guarantee.
*/
#define MLX4_EN_OVERFLOW_PERIOD (MLX4_EN_WRAP_AROUND_SEC * HZ / 2)
void mlx4_en_ptp_overflow_check(struct mlx4_en_dev *mdev)
{
bool timeout = time_is_before_jiffies(mdev->last_overflow_check +
mdev->overflow_period);
MLX4_EN_OVERFLOW_PERIOD);
unsigned long flags;
if (timeout) {
@ -237,7 +244,6 @@ static const struct ptp_clock_info mlx4_en_ptp_clock_info = {
.enable = mlx4_en_phc_enable,
};
#define MLX4_EN_WRAP_AROUND_SEC 10ULL
/* This function calculates the max shift that enables the user range
* of MLX4_EN_WRAP_AROUND_SEC values in the cycles register.
@ -258,7 +264,6 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
{
struct mlx4_dev *dev = mdev->dev;
unsigned long flags;
u64 ns, zero = 0;
/* mlx4_en_init_timestamp is called for each netdev.
* mdev->ptp_clock is common for all ports, skip initialization if
@ -282,13 +287,6 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev *mdev)
ktime_to_ns(ktime_get_real()));
write_sequnlock_irqrestore(&mdev->clock_lock, flags);
/* Calculate period in seconds to call the overflow watchdog - to make
* sure counter is checked at least once every wrap around.
*/
ns = cyclecounter_cyc2ns(&mdev->cycles, mdev->cycles.mask, zero, &zero);
do_div(ns, NSEC_PER_SEC / 2 / HZ);
mdev->overflow_period = ns;
/* Configure the PHC */
mdev->ptp_clock_info = mlx4_en_ptp_clock_info;
snprintf(mdev->ptp_clock_info.name, 16, "mlx4 ptp");

1
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
View File

@ -430,7 +430,6 @@ struct mlx4_en_dev {
seqlock_t clock_lock;
struct timecounter clock;
unsigned long last_overflow_check;
unsigned long overflow_period;
struct ptp_clock *ptp_clock;
struct ptp_clock_info ptp_clock_info;
struct notifier_block nb;