| Message ID | 20190627163133.5990-1-gpiccoli@canonical.com |
|---|---|
| State | Accepted |
| Delegated to: | David Miller |
| Headers | show |
| Series | [V4] bnx2x: Prevent ptp_task to be rescheduled indefinitely | expand |
> -----Original Message----- > From: Guilherme G. Piccoli <gpiccoli@canonical.com> > Sent: Thursday, June 27, 2019 10:02 PM > To: GR-everest-linux-l2 <GR-everest-linux-l2@marvell.com>; > netdev@vger.kernel.org; Sudarsana Reddy Kalluru <skalluru@marvell.com> > Cc: Ariel Elior <aelior@marvell.com>; gpiccoli@canonical.com; > jay.vosburgh@canonical.com > Subject: [EXT] [PATCH V4] bnx2x: Prevent ptp_task to be rescheduled > indefinitely > > External Email > > ---------------------------------------------------------------------- > Currently bnx2x ptp worker tries to read a register with timestamp > information in case of TX packet timestamping and in case it fails, the routine > reschedules itself indefinitely. This was reported as a kworker always at 100% > of CPU usage, which was narrowed down to be bnx2x ptp_task. > > By following the ioctl handler, we could narrow down the problem to an NTP > tool (chrony) requesting HW timestamping from bnx2x NIC with RX filter > zeroed; this isn't reproducible for example with ptp4l (from linuxptp) since > this tool requests a supported RX filter. > It seems NIC FW timestamp mechanism cannot work well with > RX_FILTER_NONE - driver's PTP filter init routine skips a register write to the > adapter if there's not a supported filter request. > > This patch addresses the problem of bnx2x ptp thread's everlasting > reschedule by retrying the register read 10 times; between the read > attempts the thread sleeps for an increasing amount of time starting in 1ms > to give FW some time to perform the timestamping. If it still fails after all > retries, we bail out in order to prevent an unbound resource consumption > from bnx2x. > > The patch also adds an ethtool statistic for accounting the skipped TX > timestamp packets and it reduces the priority of timestamping error > messages to prevent log flooding. The code was tested using both linuxptp > and chrony. > > Reported-and-tested-by: Przemyslaw Hausman > <przemyslaw.hausman@canonical.com> > Suggested-by: Sudarsana Reddy Kalluru <skalluru@marvell.com> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> > --- > > Thanks again for your review Sudarsana. I've addressed in this V4 your > suggestions about removing some debug messages[0]. > > [0] https://marc.info/?l=linux-netdev&m=156165243804760 > > .../net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 5 ++- > .../ethernet/broadcom/bnx2x/bnx2x_ethtool.c | 4 ++- > .../net/ethernet/broadcom/bnx2x/bnx2x_main.c | 33 ++++++++++++++---- > - .../net/ethernet/broadcom/bnx2x/bnx2x_stats.h | 3 ++ > 4 files changed, 34 insertions(+), 11 deletions(-) > > diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c > b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c > index 008ad0ca89ba..c12c1bab0fe4 100644 > --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c > +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c > @@ -3857,9 +3857,12 @@ netdev_tx_t bnx2x_start_xmit(struct sk_buff > *skb, struct net_device *dev) > > if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) { > if (!(bp->flags & TX_TIMESTAMPING_EN)) { > + bp->eth_stats.ptp_skip_tx_ts++; > BNX2X_ERR("Tx timestamping was not enabled, this > packet will not be timestamped\n"); > } else if (bp->ptp_tx_skb) { > - BNX2X_ERR("The device supports only a single > outstanding packet to timestamp, this packet will not be timestamped\n"); > + bp->eth_stats.ptp_skip_tx_ts++; > + netdev_err_once(bp->dev, > + "Device supports only a single > outstanding packet to timestamp, > +this packet won't be timestamped\n"); > } else { > skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; > /* schedule check for Tx timestamp */ diff --git > a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c > b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c > index 51fc845de31a..4a0ba6801c9e 100644 > --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c > +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c > @@ -182,7 +182,9 @@ static const struct { > { STATS_OFFSET32(driver_filtered_tx_pkt), > 4, false, "driver_filtered_tx_pkt" }, > { STATS_OFFSET32(eee_tx_lpi), > - 4, true, "Tx LPI entry count"} > + 4, true, "Tx LPI entry count"}, > + { STATS_OFFSET32(ptp_skip_tx_ts), > + 4, false, "ptp_skipped_tx_tstamp" }, > }; > > #define BNX2X_NUM_STATS ARRAY_SIZE(bnx2x_stats_arr) > diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c > b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c > index 03ac10b1cd1e..2cc14db8f0ec 100644 > --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c > +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c > @@ -15214,11 +15214,24 @@ static void bnx2x_ptp_task(struct work_struct > *work) > u32 val_seq; > u64 timestamp, ns; > struct skb_shared_hwtstamps shhwtstamps; > + bool bail = true; > + int i; > > - /* Read Tx timestamp registers */ > - val_seq = REG_RD(bp, port ? NIG_REG_P1_TLLH_PTP_BUF_SEQID : > - NIG_REG_P0_TLLH_PTP_BUF_SEQID); > - if (val_seq & 0x10000) { > + /* FW may take a while to complete timestamping; try a bit and if it's > + * still not complete, may indicate an error state - bail out then. > + */ > + for (i = 0; i < 10; i++) { > + /* Read Tx timestamp registers */ > + val_seq = REG_RD(bp, port ? > NIG_REG_P1_TLLH_PTP_BUF_SEQID : > + NIG_REG_P0_TLLH_PTP_BUF_SEQID); > + if (val_seq & 0x10000) { > + bail = false; > + break; > + } > + msleep(1 << i); > + } > + > + if (!bail) { > /* There is a valid timestamp value */ > timestamp = REG_RD(bp, port ? > NIG_REG_P1_TLLH_PTP_BUF_TS_MSB : > NIG_REG_P0_TLLH_PTP_BUF_TS_MSB); > @@ -15233,16 +15246,18 @@ static void bnx2x_ptp_task(struct work_struct > *work) > memset(&shhwtstamps, 0, sizeof(shhwtstamps)); > shhwtstamps.hwtstamp = ns_to_ktime(ns); > skb_tstamp_tx(bp->ptp_tx_skb, &shhwtstamps); > - dev_kfree_skb_any(bp->ptp_tx_skb); > - bp->ptp_tx_skb = NULL; > > DP(BNX2X_MSG_PTP, "Tx timestamp, timestamp cycles = > %llu, ns = %llu\n", > timestamp, ns); > } else { > - DP(BNX2X_MSG_PTP, "There is no valid Tx timestamp > yet\n"); > - /* Reschedule to keep checking for a valid timestamp value > */ > - schedule_work(&bp->ptp_task); > + DP(BNX2X_MSG_PTP, > + "Tx timestamp is not recorded (register read=%u)\n", > + val_seq); > + bp->eth_stats.ptp_skip_tx_ts++; > } > + > + dev_kfree_skb_any(bp->ptp_tx_skb); > + bp->ptp_tx_skb = NULL; > } > > void bnx2x_set_rx_ts(struct bnx2x *bp, struct sk_buff *skb) diff --git > a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h > b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h > index b2644ed13d06..d55e63692cf3 100644 > --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h > +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h > @@ -207,6 +207,9 @@ struct bnx2x_eth_stats { > u32 driver_filtered_tx_pkt; > /* src: Clear-on-Read register; Will not survive PMF Migration */ > u32 eee_tx_lpi; > + > + /* PTP */ > + u32 ptp_skip_tx_ts; > }; > > struct bnx2x_eth_q_stats { > -- > 2.22.0 Thanks for the changes. Acked-by: Sudarsana Reddy Kalluru <skalluru@marvell.com>
On 28/06/2019 02:22, Sudarsana Reddy Kalluru wrote: > [...] > Thanks for the changes. > > Acked-by: Sudarsana Reddy Kalluru <skalluru@marvell.com> > Thanks a lot Sudarsana! David, do you think it's still possible to get this merged as a fix in 5.2 cycle, or it's gonna go in 5.3? Thanks, Guilherme
From: "Guilherme G. Piccoli" <gpiccoli@canonical.com> Date: Thu, 27 Jun 2019 13:31:33 -0300 > Currently bnx2x ptp worker tries to read a register with timestamp > information in case of TX packet timestamping and in case it fails, > the routine reschedules itself indefinitely. This was reported as a > kworker always at 100% of CPU usage, which was narrowed down to be > bnx2x ptp_task. > > By following the ioctl handler, we could narrow down the problem to > an NTP tool (chrony) requesting HW timestamping from bnx2x NIC with > RX filter zeroed; this isn't reproducible for example with ptp4l > (from linuxptp) since this tool requests a supported RX filter. > It seems NIC FW timestamp mechanism cannot work well with > RX_FILTER_NONE - driver's PTP filter init routine skips a register > write to the adapter if there's not a supported filter request. > > This patch addresses the problem of bnx2x ptp thread's everlasting > reschedule by retrying the register read 10 times; between the read > attempts the thread sleeps for an increasing amount of time starting > in 1ms to give FW some time to perform the timestamping. If it still > fails after all retries, we bail out in order to prevent an unbound > resource consumption from bnx2x. > > The patch also adds an ethtool statistic for accounting the skipped > TX timestamp packets and it reduces the priority of timestamping > error messages to prevent log flooding. The code was tested using > both linuxptp and chrony. > > Reported-and-tested-by: Przemyslaw Hausman <przemyslaw.hausman@canonical.com> > Suggested-by: Sudarsana Reddy Kalluru <skalluru@marvell.com> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> Applied and queued up for -stable.
diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c index 008ad0ca89ba..c12c1bab0fe4 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c @@ -3857,9 +3857,12 @@ netdev_tx_t bnx2x_start_xmit(struct sk_buff *skb, struct net_device *dev) if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) { if (!(bp->flags & TX_TIMESTAMPING_EN)) { + bp->eth_stats.ptp_skip_tx_ts++; BNX2X_ERR("Tx timestamping was not enabled, this packet will not be timestamped\n"); } else if (bp->ptp_tx_skb) { - BNX2X_ERR("The device supports only a single outstanding packet to timestamp, this packet will not be timestamped\n"); + bp->eth_stats.ptp_skip_tx_ts++; + netdev_err_once(bp->dev, + "Device supports only a single outstanding packet to timestamp, this packet won't be timestamped\n"); } else { skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; /* schedule check for Tx timestamp */ diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c index 51fc845de31a..4a0ba6801c9e 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c @@ -182,7 +182,9 @@ static const struct { { STATS_OFFSET32(driver_filtered_tx_pkt), 4, false, "driver_filtered_tx_pkt" }, { STATS_OFFSET32(eee_tx_lpi), - 4, true, "Tx LPI entry count"} + 4, true, "Tx LPI entry count"}, + { STATS_OFFSET32(ptp_skip_tx_ts), + 4, false, "ptp_skipped_tx_tstamp" }, }; #define BNX2X_NUM_STATS ARRAY_SIZE(bnx2x_stats_arr) diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c index 03ac10b1cd1e..2cc14db8f0ec 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c @@ -15214,11 +15214,24 @@ static void bnx2x_ptp_task(struct work_struct *work) u32 val_seq; u64 timestamp, ns; struct skb_shared_hwtstamps shhwtstamps; + bool bail = true; + int i; - /* Read Tx timestamp registers */ - val_seq = REG_RD(bp, port ? NIG_REG_P1_TLLH_PTP_BUF_SEQID : - NIG_REG_P0_TLLH_PTP_BUF_SEQID); - if (val_seq & 0x10000) { + /* FW may take a while to complete timestamping; try a bit and if it's + * still not complete, may indicate an error state - bail out then. + */ + for (i = 0; i < 10; i++) { + /* Read Tx timestamp registers */ + val_seq = REG_RD(bp, port ? NIG_REG_P1_TLLH_PTP_BUF_SEQID : + NIG_REG_P0_TLLH_PTP_BUF_SEQID); + if (val_seq & 0x10000) { + bail = false; + break; + } + msleep(1 << i); + } + + if (!bail) { /* There is a valid timestamp value */ timestamp = REG_RD(bp, port ? NIG_REG_P1_TLLH_PTP_BUF_TS_MSB : NIG_REG_P0_TLLH_PTP_BUF_TS_MSB); @@ -15233,16 +15246,18 @@ static void bnx2x_ptp_task(struct work_struct *work) memset(&shhwtstamps, 0, sizeof(shhwtstamps)); shhwtstamps.hwtstamp = ns_to_ktime(ns); skb_tstamp_tx(bp->ptp_tx_skb, &shhwtstamps); - dev_kfree_skb_any(bp->ptp_tx_skb); - bp->ptp_tx_skb = NULL; DP(BNX2X_MSG_PTP, "Tx timestamp, timestamp cycles = %llu, ns = %llu\n", timestamp, ns); } else { - DP(BNX2X_MSG_PTP, "There is no valid Tx timestamp yet\n"); - /* Reschedule to keep checking for a valid timestamp value */ - schedule_work(&bp->ptp_task); + DP(BNX2X_MSG_PTP, + "Tx timestamp is not recorded (register read=%u)\n", + val_seq); + bp->eth_stats.ptp_skip_tx_ts++; } + + dev_kfree_skb_any(bp->ptp_tx_skb); + bp->ptp_tx_skb = NULL; } void bnx2x_set_rx_ts(struct bnx2x *bp, struct sk_buff *skb) diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h index b2644ed13d06..d55e63692cf3 100644 --- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h +++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_stats.h @@ -207,6 +207,9 @@ struct bnx2x_eth_stats { u32 driver_filtered_tx_pkt; /* src: Clear-on-Read register; Will not survive PMF Migration */ u32 eee_tx_lpi; + + /* PTP */ + u32 ptp_skip_tx_ts; }; struct bnx2x_eth_q_stats {
Currently bnx2x ptp worker tries to read a register with timestamp information in case of TX packet timestamping and in case it fails, the routine reschedules itself indefinitely. This was reported as a kworker always at 100% of CPU usage, which was narrowed down to be bnx2x ptp_task. By following the ioctl handler, we could narrow down the problem to an NTP tool (chrony) requesting HW timestamping from bnx2x NIC with RX filter zeroed; this isn't reproducible for example with ptp4l (from linuxptp) since this tool requests a supported RX filter. It seems NIC FW timestamp mechanism cannot work well with RX_FILTER_NONE - driver's PTP filter init routine skips a register write to the adapter if there's not a supported filter request. This patch addresses the problem of bnx2x ptp thread's everlasting reschedule by retrying the register read 10 times; between the read attempts the thread sleeps for an increasing amount of time starting in 1ms to give FW some time to perform the timestamping. If it still fails after all retries, we bail out in order to prevent an unbound resource consumption from bnx2x. The patch also adds an ethtool statistic for accounting the skipped TX timestamp packets and it reduces the priority of timestamping error messages to prevent log flooding. The code was tested using both linuxptp and chrony. Reported-and-tested-by: Przemyslaw Hausman <przemyslaw.hausman@canonical.com> Suggested-by: Sudarsana Reddy Kalluru <skalluru@marvell.com> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> --- Thanks again for your review Sudarsana. I've addressed in this V4 your suggestions about removing some debug messages[0]. [0] https://marc.info/?l=linux-netdev&m=156165243804760 .../net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 5 ++- .../ethernet/broadcom/bnx2x/bnx2x_ethtool.c | 4 ++- .../net/ethernet/broadcom/bnx2x/bnx2x_main.c | 33 ++++++++++++++----- .../net/ethernet/broadcom/bnx2x/bnx2x_stats.h | 3 ++ 4 files changed, 34 insertions(+), 11 deletions(-)