Date: Wed, 24 May 2023 13:31:13 +0200
From: Jiri Pirko <jiri@...nulli.us>
To: Manish Chopra <manishc@...vell.com>
Cc: kuba@...nel.org, netdev@...r.kernel.org, aelior@...vell.com,
	palok@...vell.com, Sudarsana Kalluru <skalluru@...vell.com>,
	David Miller <davem@...emloft.net>
Subject: Re: [PATCH v5 net] qede: Fix scheduling while atomic

Tue, May 23, 2023 at 04:42:35PM CEST, manishc@...vell.com wrote:
>Bonding module collects the statistics while holding
>the spinlock, beneath that qede->qed driver statistics
>flow gets scheduled out due to usleep_range() used in PTT
>acquire logic which results into below bug and traces -
>
>[ 3673.988874] Hardware name: HPE ProLiant DL365 Gen10 Plus/ProLiant DL365 Gen10 Plus, BIOS A42 10/29/2021
>[ 3673.988878] Call Trace:
>[ 3673.988891]  dump_stack_lvl+0x34/0x44
>[ 3673.988908]  __schedule_bug.cold+0x47/0x53
>[ 3673.988918]  __schedule+0x3fb/0x560
>[ 3673.988929]  schedule+0x43/0xb0
>[ 3673.988932]  schedule_hrtimeout_range_clock+0xbf/0x1b0
>[ 3673.988937]  ? __hrtimer_init+0xc0/0xc0
>[ 3673.988950]  usleep_range+0x5e/0x80
>[ 3673.988955]  qed_ptt_acquire+0x2b/0xd0 [qed]
>[ 3673.988981]  _qed_get_vport_stats+0x141/0x240 [qed]
>[ 3673.989001]  qed_get_vport_stats+0x18/0x80 [qed]
>[ 3673.989016]  qede_fill_by_demand_stats+0x37/0x400 [qede]
>[ 3673.989028]  qede_get_stats64+0x19/0xe0 [qede]
>[ 3673.989034]  dev_get_stats+0x5c/0xc0
>[ 3673.989045]  netstat_show.constprop.0+0x52/0xb0
>[ 3673.989055]  dev_attr_show+0x19/0x40
>[ 3673.989065]  sysfs_kf_seq_show+0x9b/0xf0
>[ 3673.989076]  seq_read_iter+0x120/0x4b0
>[ 3673.989087]  new_sync_read+0x118/0x1a0
>[ 3673.989095]  vfs_read+0xf3/0x180
>[ 3673.989099]  ksys_read+0x5f/0xe0
>[ 3673.989102]  do_syscall_64+0x3b/0x90
>[ 3673.989109]  entry_SYSCALL_64_after_hwframe+0x44/0xae

You mention "bonding module" at the beginning of this description. Where
exactly is that shown in the trace?

I guess that the "spinlock" you talk about is "dev_base_lock", isn't
it?


>[ 3673.989115] RIP: 0033:0x7f8467d0b082
>[ 3673.989119] Code: c0 e9 b2 fe ff ff 50 48 8d 3d ca 05 08 00 e8 35 e7 01 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
>[ 3673.989121] RSP: 002b:00007ffffb21fd08 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>[ 3673.989127] RAX: ffffffffffffffda RBX: 000000000100eca0 RCX: 00007f8467d0b082
>[ 3673.989128] RDX: 00000000000003ff RSI: 00007ffffb21fdc0 RDI: 0000000000000003
>[ 3673.989130] RBP: 00007f8467b96028 R08: 0000000000000010 R09: 00007ffffb21ec00
>[ 3673.989132] R10: 00007ffffb27b170 R11: 0000000000000246 R12: 00000000000000f0
>[ 3673.989134] R13: 0000000000000003 R14: 00007f8467b92000 R15: 0000000000045a05
>[ 3673.989139] CPU: 30 PID: 285188 Comm: read_all Kdump: loaded Tainted: G        W  OE
>
>Fix this by collecting the statistics asynchronously from a periodic
>delayed work scheduled at default stats coalescing interval and return
>the recent copy of statisitcs from .ndo_get_stats64(), also add ability
>to configure/retrieve stats coalescing interval using below commands -
>
>ethtool -C ethx stats-block-usecs <val>
>ethtool -c ethx
>
>Fixes: 133fac0eedc3 ("qede: Add basic ethtool support")
>Cc: Sudarsana Kalluru <skalluru@...vell.com>
>Cc: David Miller <davem@...emloft.net>
>Signed-off-by: Manish Chopra <manishc@...vell.com>
>---
>v1->v2:
> - Fixed checkpatch and kdoc warnings.
>v2->v3:
> - Moving the changelog after tags.
>v3->v4:
> - Changes to collect stats periodically using delayed work
>   and add ability to configure/retrieve stats coalescing
>   interval using ethtool
> - Modified commit description to reflect the changes
>v4->v5:
> - Renamed the variables (s/ticks/usecs and s/interval/ticks)
> - Relaxed the stats usecs coalescing configuration to allow
>   user to set any range of values and also while getting return
>   the exact value configured
> - Usage of usecs_to_jiffies() wherever applicable
> - Cosmetic change for logs/comments
>---
> drivers/net/ethernet/qlogic/qede/qede.h       |  4 +++
> .../net/ethernet/qlogic/qede/qede_ethtool.c   | 26 ++++++++++++--
> drivers/net/ethernet/qlogic/qede/qede_main.c  | 35 ++++++++++++++++++-
> 3 files changed, 62 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/net/ethernet/qlogic/qede/qede.h b/drivers/net/ethernet/qlogic/qede/qede.h
>index f90dcfe9ee68..8a63f99d499c 100644
>--- a/drivers/net/ethernet/qlogic/qede/qede.h
>+++ b/drivers/net/ethernet/qlogic/qede/qede.h
>@@ -271,6 +271,10 @@ struct qede_dev {
> #define QEDE_ERR_WARN			3
> 
> 	struct qede_dump_info		dump_info;
>+	struct delayed_work		periodic_task;
>+	unsigned long			stats_coal_ticks;
>+	u32				stats_coal_usecs;
>+	spinlock_t			stats_lock; /* lock for vport stats access */
> };
> 
> enum QEDE_STATE {
>diff --git a/drivers/net/ethernet/qlogic/qede/qede_ethtool.c b/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
>index 8284c4c1528f..a6498eb7cbd7 100644
>--- a/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
>+++ b/drivers/net/ethernet/qlogic/qede/qede_ethtool.c
>@@ -426,6 +426,8 @@ static void qede_get_ethtool_stats(struct net_device *dev,
> 		}
> 	}
> 
>+	spin_lock(&edev->stats_lock);
>+
> 	for (i = 0; i < QEDE_NUM_STATS; i++) {
> 		if (qede_is_irrelevant_stat(edev, i))
> 			continue;
>@@ -435,6 +437,8 @@ static void qede_get_ethtool_stats(struct net_device *dev,
> 		buf++;
> 	}
> 
>+	spin_unlock(&edev->stats_lock);
>+
> 	__qede_unlock(edev);
> }
> 
>@@ -817,6 +821,7 @@ static int qede_get_coalesce(struct net_device *dev,
> 
> 	coal->rx_coalesce_usecs = rx_coal;
> 	coal->tx_coalesce_usecs = tx_coal;
>+	coal->stats_block_coalesce_usecs = edev->stats_coal_usecs;
> 
> 	return rc;
> }
>@@ -830,6 +835,21 @@ int qede_set_coalesce(struct net_device *dev, struct ethtool_coalesce *coal,
> 	int i, rc = 0;
> 	u16 rxc, txc;
> 
>+	if (edev->stats_coal_usecs != coal->stats_block_coalesce_usecs) {
>+		bool stats_coal_enabled;
>+
>+		stats_coal_enabled = edev->stats_coal_usecs ? true : false;
>+
>+		edev->stats_coal_usecs = coal->stats_block_coalesce_usecs;
>+		edev->stats_coal_ticks = usecs_to_jiffies(coal->stats_block_coalesce_usecs);
>+
>+		if (!stats_coal_enabled)
>+			schedule_delayed_work(&edev->periodic_task, 0);

What is the point of schedule here? Don't you want to rather schedule
if (stats_coal_enabled == true) ??


>+
>+		DP_INFO(edev, "Configured stats coal ticks=%lu jiffies\n",
>+			edev->stats_coal_ticks);
>+	}
>+
> 	if (!netif_running(dev)) {
> 		DP_INFO(edev, "Interface is down\n");
> 		return -EINVAL;
>@@ -2236,7 +2256,8 @@ static int qede_get_per_coalesce(struct net_device *dev,
> }
> 
> static const struct ethtool_ops qede_ethtool_ops = {
>-	.supported_coalesce_params	= ETHTOOL_COALESCE_USECS,
>+	.supported_coalesce_params	= ETHTOOL_COALESCE_USECS |
>+					  ETHTOOL_COALESCE_STATS_BLOCK_USECS,
> 	.get_link_ksettings		= qede_get_link_ksettings,
> 	.set_link_ksettings		= qede_set_link_ksettings,
> 	.get_drvinfo			= qede_get_drvinfo,
>@@ -2287,7 +2308,8 @@ static const struct ethtool_ops qede_ethtool_ops = {
> };
> 
> static const struct ethtool_ops qede_vf_ethtool_ops = {
>-	.supported_coalesce_params	= ETHTOOL_COALESCE_USECS,
>+	.supported_coalesce_params	= ETHTOOL_COALESCE_USECS |
>+					  ETHTOOL_COALESCE_STATS_BLOCK_USECS,
> 	.get_link_ksettings		= qede_get_link_ksettings,
> 	.get_drvinfo			= qede_get_drvinfo,
> 	.get_msglevel			= qede_get_msglevel,
>diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
>index 06c6a5813606..61cc10968988 100644
>--- a/drivers/net/ethernet/qlogic/qede/qede_main.c
>+++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
>@@ -308,6 +308,8 @@ void qede_fill_by_demand_stats(struct qede_dev *edev)
> 
> 	edev->ops->get_vport_stats(edev->cdev, &stats);
> 
>+	spin_lock(&edev->stats_lock);
>+
> 	p_common->no_buff_discards = stats.common.no_buff_discards;
> 	p_common->packet_too_big_discard = stats.common.packet_too_big_discard;
> 	p_common->ttl0_discard = stats.common.ttl0_discard;
>@@ -405,6 +407,8 @@ void qede_fill_by_demand_stats(struct qede_dev *edev)
> 		p_ah->tx_1519_to_max_byte_packets =
> 		    stats.ah.tx_1519_to_max_byte_packets;
> 	}
>+
>+	spin_unlock(&edev->stats_lock);
> }
> 
> static void qede_get_stats64(struct net_device *dev,
>@@ -413,9 +417,10 @@ static void qede_get_stats64(struct net_device *dev,
> 	struct qede_dev *edev = netdev_priv(dev);
> 	struct qede_stats_common *p_common;
> 
>-	qede_fill_by_demand_stats(edev);
> 	p_common = &edev->stats.common;
> 
>+	spin_lock(&edev->stats_lock);
>+
> 	stats->rx_packets = p_common->rx_ucast_pkts + p_common->rx_mcast_pkts +
> 			    p_common->rx_bcast_pkts;
> 	stats->tx_packets = p_common->tx_ucast_pkts + p_common->tx_mcast_pkts +
>@@ -435,6 +440,8 @@ static void qede_get_stats64(struct net_device *dev,
> 		stats->collisions = edev->stats.bb.tx_total_collisions;
> 	stats->rx_crc_errors = p_common->rx_crc_errors;
> 	stats->rx_frame_errors = p_common->rx_align_errors;
>+
>+	spin_unlock(&edev->stats_lock);
> }
> 
> #ifdef CONFIG_QED_SRIOV
>@@ -1000,6 +1007,21 @@ static void qede_unlock(struct qede_dev *edev)
> 	rtnl_unlock();
> }
> 
>+static void qede_periodic_task(struct work_struct *work)
>+{
>+	struct qede_dev *edev = container_of(work, struct qede_dev,
>+					     periodic_task.work);
>+
>+	if (test_bit(QEDE_SP_DISABLE, &edev->sp_flags))
>+		return;
>+
>+	if (edev->stats_coal_usecs) {

Why don't you cancel the work when you don't want this to happen?


>+		qede_fill_by_demand_stats(edev);
>+		schedule_delayed_work(&edev->periodic_task,
>+				      edev->stats_coal_ticks);
>+	}
>+}
>+
> static void qede_sp_task(struct work_struct *work)
> {
> 	struct qede_dev *edev = container_of(work, struct qede_dev,
>@@ -1208,7 +1230,9 @@ static int __qede_probe(struct pci_dev *pdev, u32 dp_module, u8 dp_level,
> 		 * from there, although it's unlikely].
> 		 */
> 		INIT_DELAYED_WORK(&edev->sp_task, qede_sp_task);
>+		INIT_DELAYED_WORK(&edev->periodic_task, qede_periodic_task);
> 		mutex_init(&edev->qede_lock);
>+		spin_lock_init(&edev->stats_lock);
> 
> 		rc = register_netdev(edev->ndev);
> 		if (rc) {
>@@ -1233,6 +1257,11 @@ static int __qede_probe(struct pci_dev *pdev, u32 dp_module, u8 dp_level,
> 	edev->rx_copybreak = QEDE_RX_HDR_SIZE;
> 
> 	qede_log_probe(edev);
>+
>+	edev->stats_coal_usecs = USEC_PER_SEC;
>+	edev->stats_coal_ticks = usecs_to_jiffies(USEC_PER_SEC);
>+	schedule_delayed_work(&edev->periodic_task, 0);
>+
> 	return 0;
> 
> err4:
>@@ -1301,6 +1330,7 @@ static void __qede_remove(struct pci_dev *pdev, enum qede_remove_mode mode)
> 		unregister_netdev(ndev);
> 
> 		cancel_delayed_work_sync(&edev->sp_task);
>+		cancel_delayed_work_sync(&edev->periodic_task);
> 
> 		edev->ops->common->set_power_state(cdev, PCI_D0);
> 
>@@ -2571,6 +2601,9 @@ static void qede_recovery_handler(struct qede_dev *edev)
> 
> 	DP_NOTICE(edev, "Starting a recovery process\n");
> 
>+	/* disable periodic stats */
>+	edev->stats_coal_usecs = 0;

You disable but never enable again. Why?

Also, why don't you do:
cancel_delayed_work_sync(&edev->periodic_task)
here instead?


>+
> 	/* No need to acquire first the qede_lock since is done by qede_sp_task
> 	 * before calling this function.
> 	 */
>-- 
>2.27.0
>
>

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