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Date: Fri, 26 Apr 2013 05:24:12 +0300
From: Or Gerlitz <or.gerlitz@...il.com>
To: Eric Dumazet <eric.dumazet@...il.com>
Cc: Amir Vadai <amirv@...lanox.com>,
"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Richard Cochran <richardcochran@...il.com>,
Or Gerlitz <ogerlitz@...lanox.com>,
Eugenia Emantayev <eugenia@...lanox.com>
Subject: Re: [PATCH net-next V3 5/5] net/mlx4_en: Add a service task
On Fri, Apr 26, 2013 at 3:13 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Tue, 2013-04-23 at 19:06 +0300, Amir Vadai wrote:
> > Add a service task to run tasks that needed to be executed periodically.
> > Currently the only task is a watchdog to catch NIC clock overflow, to
> > make timestamping accurate. Will move the statistics task into this framework in a >> later patch.
> >
> > Signed-off-by: Amir Vadai <amirv@...lanox.com>
> > ---
> > drivers/net/ethernet/mellanox/mlx4/en_clock.c | 19
> > +++++++++++++++++++
> > drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 24
> > ++++++++++++++++++++++++
> > drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 4 ++++
> > 3 files changed, 47 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> > b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> > index 501c72f..2f18121 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/en_clock.c
> > @@ -129,4 +129,23 @@ void mlx4_en_init_timestamp(struct mlx4_en_dev
> > *mdev)
> >
> > timecounter_init(&mdev->clock, &mdev->cycles,
> > ktime_to_ns(ktime_get_real()));
> > +
> > + /* Calculate period in seconds to call the overflow watchdog - to
> > make
> > + * sure counter is checked at least once every wrap around.
> > + */
> > + mdev->overflow_period =
> > + (cyclecounter_cyc2ns(&mdev->cycles,
> > + mdev->cycles.mask) / NSEC_PER_SEC / 2)
> > + * HZ;
> > +}
> > +
> > +void mlx4_en_ptp_overflow_check(struct mlx4_en_dev *mdev)
> > +{
> > + bool timeout = time_is_before_jiffies(mdev->last_overflow_check +
> > + mdev->overflow_period);
> > +
> > + if (timeout) {
> > + timecounter_read(&mdev->clock);
> > + mdev->last_overflow_check = jiffies;
> > + }
> > }
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > index 4cb9f32..f4f88b8 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> > @@ -1361,6 +1361,26 @@ static void mlx4_en_do_get_stats(struct
> > work_struct *work)
> > mutex_unlock(&mdev->state_lock);
> > }
> >
> > +/* mlx4_en_service_task - Run service task for tasks that needed to be
> > done
> > + * periodically
> > + */
> > +static void mlx4_en_service_task(struct work_struct *work)
> > +{
> > + struct delayed_work *delay = to_delayed_work(work);
> > + struct mlx4_en_priv *priv = container_of(delay, struct
> > mlx4_en_priv,
> > + service_task);
> > + struct mlx4_en_dev *mdev = priv->mdev;
> > +
> > + mutex_lock(&mdev->state_lock);
> > + if (mdev->device_up) {
> > + mlx4_en_ptp_overflow_check(mdev);
> > +
> > + queue_delayed_work(mdev->workqueue, &priv->service_task,
> > + SERVICE_TASK_DELAY);
> > + }
> > + mutex_unlock(&mdev->state_lock);
> > +}
> > +
>
> What if mlx4_en_init_timestamp() was not called ?
>
> if (mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS)
> mlx4_en_init_timestamp(mdev);
>
> Answer : a NULL deref
Hi Eric,
This is fixed in "[PATCH V1 net-next 2/8] net/mlx4_en: Disable HW
clock overflow check when no HW support"
http://marc.info/?l=linux-netdev&m=136690338314540&w=2
Or.
>
> [ 67.414454] BUG: unable to handle kernel NULL pointer dereference at
> (null)
> [ 67.422313] IP: [<ffffffff810c9db7>] timecounter_read+0x17/0x50
> [ 67.428255] PGD c5faa3067 PUD c6002f067 PMD 0
> [ 67.432747] Oops: 0000 [#1] SMP
> [ 67.436007] Modules linked in: msr cpuid genrtc mlx4_en ib_uverbs
> mlx4_ib ib_sa ib_mad ib_core mlx4_core libcrc32c mdio ipv6
> [ 67.448615] CPU 0
> [ 67.450457] Pid: 1321, comm: kworker/u:7 Not tainted 3.9.0-smp-DEV #328
> Intel TBG,ICH10/I
> [ 67.459770] RIP: 0010:[<ffffffff810c9db7>] [<ffffffff810c9db7>]
> timecounter_read+0x17/0x50
> [ 67.468130] RSP: 0018:ffff880660635d88 EFLAGS: 00010296
> [ 67.473438] RAX: 0000000000000000 RBX: ffff8806604ce368 RCX:
> ffff88064f8e1d58
> [ 67.480568] RDX: 00000000fffc72a1 RSI: ffffffff81b18510 RDI:
> 0000000000000000
> [ 67.487695] RBP: ffff880660635d98 R08: eac0000000000000 R09:
> dfe649cdda2e1d58
> [ 67.494824] R10: dfe649cdda2e1d58 R11: 0000000000000000 R12:
> ffff88064f8e1d58
> [ 67.501953] R13: ffff8806604ce200 R14: 0000000000000000 R15:
> ffff8806604ce005
> [ 67.509085] FS: 0000000000000000(0000) GS:ffff88067fc00000(0000)
> knlGS:0000000000000000
> [ 67.517168] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 67.522910] CR2: 0000000000000000 CR3: 0000000c6074d000 CR4:
> 00000000000007f0
> [ 67.530037] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [ 67.537166] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7:
> 0000000000000400
> [ 67.544298] Process kworker/u:7 (pid: 1321, threadinfo
> ffff880660634000, task ffff880660d4d820)
> [ 67.552986] Stack:
> [ 67.554997] ffff88067fc127c0 ffff8806604ce200 ffff880660635db8
> ffffffffa01e1274
> [ 67.562457] ffff8806604ce210 ffff8806604ce210 ffff880660635de8
> ffffffffa01dc78e
> [ 67.569917] ffffffff81b18500 ffff880c612ec540 ffffffff81b18500
> ffff8806604ce000
> [ 67.577377] Call Trace:
> [ 67.579826] [<ffffffffa01e1274>] mlx4_en_ptp_overflow_check+0x44/0x60
> [mlx4_en]
> [ 67.587223] [<ffffffffa01dc78e>] mlx4_en_service_task+0x3e/0x70
> [mlx4_en]
> [ 67.594099] [<ffffffff810a1df5>] process_one_work+0x175/0x3f0
> [ 67.599926] [<ffffffff810a3208>] worker_thread+0x118/0x370
> [ 67.605494] [<ffffffff810a30f0>] ? manage_workers+0x390/0x390
> [ 67.611325] [<ffffffff810a91d0>] kthread+0xc0/0xd0
> [ 67.616199] [<ffffffff810a9110>] ? flush_kthread_worker+0x80/0x80
> [ 67.622374] [<ffffffff815c699c>] ret_from_fork+0x7c/0xb0
> [ 67.627768] [<ffffffff810a9110>] ? flush_kthread_worker+0x80/0x80
> [ 67.633941] Code: 8b 65 f8 48 8b 5d f0 c9 c3 66 66 2e 0f 1f 84 00 00 00
> 00 00 66 66 66 66 90 55 48 89 e5 53 48 89 fb 48 83 ec 08 48 8b 07 48 89 c7
> <ff> 10 48 8b 0b 48 89 c2 48 2b 53 08 48 23 51 08 8b 71 10 8b 49
> [ 67.653910] RIP [<ffffffff810c9db7>] timecounter_read+0x17/0x50
> [ 67.659931] RSP <ffff880660635d88>
> [ 67.663418] CR2: 0000000000000000
> [ 67.666757] ---[ end trace 5a2c9af6569fc2bb ]---
> [ 67.671388] Kernel panic - not syncing: Fatal exception
>
>
>
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