Re: [PATCH v2 2/4] BNX2FC: hung task timeout warning observed when rmmod bnx2x with active FCoE targets

[Tomas Henzl <thenzl-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 09/26/2013 07:01 AM, Eddie Wai wrote:
> [v2] - removed the interface->enabled flag setting which prevented the
>        fcoe ctlr link from being brought back up after a MTU change

Maybe I miss something but it seems to me that the previous version
has been taken into the for-next branch - 881e188ec7078f6850170ca72cc60621fe0672e1

If it is so, and the V2 is the right one, post a V1-V2 diff

Thanks, Tomas

>
> A rtnl_lock deadlock was observed from the rmmod thread where it
> tries to unregister the fcoe_ctlr device.  This unregistration
> triggered a flush of the sysfs queue of the associated ctlr and led to
> a call to the set_fcoe_ctlr_enabled routine.  This will eventually propagate
> down to call the bnx2fc_disable routine and contented for the rtnl_lock
> in the same context.
>
> This patch creates a subset of the bnx2fc_enable/disable routine which
> removes the unnecesary rtnl_lock and the bnx2fc_dev_lock acquisition from
> the set_fcoe_ctlr_enabled path.
>
>  kernel: INFO: task rmmod:7874 blocked for more than 120 seconds.
>  kernel:      Tainted: G        W  ---------------    2.6.32-415.0.1.el6.x86_64 #1
>  kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>  kernel: rmmod         D 000000000000000f     0  7874   6518 0x00000080
>  kernel: ffff88022158f7d8 0000000000000086 0000000000000000 0000000000000000
>  kernel: ffff88023fe72600 ffff88043c74d410 ffff88043c74d400 ffff88043c74d000
>  kernel: ffff88021ecbe5f8 ffff88022158ffd8 000000000000fbc8 ffff88021ecbe5f8
>  kernel: Call Trace:
>  kernel: [<ffffffff81525985>] schedule_timeout+0x215/0x2e0
>  kernel: [<ffffffff810680c0>] ? pick_next_task_fair+0xd0/0x130
>  kernel: [<ffffffff81524858>] ? schedule+0x178/0x3b2
>  kernel: [<ffffffff81525603>] wait_for_common+0x123/0x180
>  kernel: [<ffffffff81066b40>] ? default_wake_function+0x0/0x20
>  kernel: [<ffffffff811a486e>] ? ifind_fast+0x5e/0xb0
>  kernel: [<ffffffff8152571d>] wait_for_completion+0x1d/0x20
>  kernel: [<ffffffff81203868>] sysfs_addrm_finish+0x228/0x270
>  kernel: [<ffffffff812014ab>] sysfs_hash_and_remove+0x5b/0x90
>  kernel: [<ffffffff812056af>] sysfs_remove_group+0x5f/0x100
>  kernel: [<ffffffff81367e8b>] device_remove_groups+0x3b/0x60
>  kernel: [<ffffffff8136811d>] device_remove_attrs+0x3d/0x90
>  kernel: [<ffffffff81368295>] device_del+0x125/0x1e0
>  kernel: [<ffffffff81368372>] device_unregister+0x22/0x60
>  kernel: [<ffffffffa038ead2>] fcoe_ctlr_device_delete+0xe2/0xf4 [libfcoe]
>  kernel: [<ffffffffa03c43cb>] bnx2fc_interface_release+0x5b/0x90 [bnx2fc]
>  kernel: [<ffffffffa03c4370>] ? bnx2fc_interface_release+0x0/0x90 [bnx2fc]
>  kernel: [<ffffffff812835e7>] kref_put+0x37/0x70
>  kernel: [<ffffffffa03c4192>] __bnx2fc_destroy+0x72/0xa0 [bnx2fc]
>  kernel: [<ffffffffa03c5265>] bnx2fc_ulp_exit+0xf5/0x160 [bnx2fc]    <- got bnx2fc_dev_lock mutex_lock
>  kernel: [<ffffffffa03b03c6>] cnic_ulp_exit+0xb6/0xc0 [cnic]
>  kernel: [<ffffffffa03b5418>] cnic_netdev_event+0x368/0x370 [cnic]
>  kernel: [<ffffffffa038c56c>] ? fcoe_del_netdev_mapping+0x8c/0xa0 [libfcoe]
>  kernel: [<ffffffff8152a6e5>] notifier_call_chain+0x55/0x80
>  kernel: [<ffffffff810a0a46>] raw_notifier_call_chain+0x16/0x20
>  kernel: [<ffffffff81459beb>] call_netdevice_notifiers+0x1b/0x20
>  kernel: [<ffffffff8145ab34>] rollback_registered_many+0x154/0x280
>  kernel: [<ffffffff8145ad08>] rollback_registered+0x38/0x50
>  kernel: [<ffffffff8145ad78>] unregister_netdevice_queue+0x58/0xa0
>  kernel: [<ffffffff8145add0>] unregister_netdevice+0x10/0x20
>  kernel: [<ffffffff8145adfe>] unregister_netdev+0x1e/0x30                  <- got rtnl_lock!!!!!!!!!
>  kernel: [<ffffffffa0122278>] __bnx2x_remove+0x48/0x270 [bnx2x] <- got & rel rtnl_lock
>  kernel: [<ffffffffa0122554>] bnx2x_remove_one+0x44/0x80 [bnx2x]
>  kernel: [<ffffffff812a3af7>] pci_device_remove+0x37/0x70
>  kernel: [<ffffffff8136b2ef>] __device_release_driver+0x6f/0xe0
>  kernel: [<ffffffff8136b428>] driver_detach+0xc8/0xd0
>  kernel: [<ffffffff8136a22e>] bus_remove_driver+0x8e/0x110
>  kernel: [<ffffffff8136bc12>] driver_unregister+0x62/0xa0
>  kernel: [<ffffffff812a3e04>] pci_unregister_driver+0x44/0xb0
>  kernel: [<ffffffffa0191954>] bnx2x_cleanup+0x18/0x73 [bnx2x]
>  kernel: [<ffffffff810b8be4>] sys_delete_module+0x194/0x260
>  kernel: [<ffffffff810e1347>] ? audit_syscall_entry+0x1d7/0x200
>  kernel: [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
>
> Signed-off-by: Eddie Wai <eddie.wai-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
> ---
>  drivers/scsi/bnx2fc/bnx2fc_fcoe.c |   59 +++++++++++++++++++++++++++---------
>  1 files changed, 44 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> index 69ac554..7a25766 100644
> --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> @@ -2004,6 +2004,24 @@ static void bnx2fc_ulp_init(struct cnic_dev *dev)
>  		set_bit(BNX2FC_CNIC_REGISTERED, &hba->reg_with_cnic);
>  }
>  
> +/* Assumes rtnl_lock and the bnx2fc_dev_lock are already taken */
> +static int __bnx2fc_disable(struct fcoe_ctlr *ctlr)
> +{
> +	struct bnx2fc_interface *interface = fcoe_ctlr_priv(ctlr);
> +
> +	if (interface->enabled == true) {
> +		if (!ctlr->lp) {
> +			pr_err(PFX "__bnx2fc_disable: lport not found\n");
> +			return -ENODEV;
> +		} else {
> +			interface->enabled = false;
> +			fcoe_ctlr_link_down(ctlr);
> +			fcoe_clean_pending_queue(ctlr->lp);
> +		}
> +	}
> +	return 0;
> +}
> +
>  /**
>   * Deperecated: Use bnx2fc_enabled()
>   */
> @@ -2018,20 +2036,34 @@ static int bnx2fc_disable(struct net_device *netdev)
>  
>  	interface = bnx2fc_interface_lookup(netdev);
>  	ctlr = bnx2fc_to_ctlr(interface);
> -	if (!interface || !ctlr->lp) {
> +
> +	if (!interface) {
>  		rc = -ENODEV;
> -		printk(KERN_ERR PFX "bnx2fc_disable: interface or lport not found\n");
> +		pr_err(PFX "bnx2fc_disable: interface not found\n");
>  	} else {
> -		interface->enabled = false;
> -		fcoe_ctlr_link_down(ctlr);
> -		fcoe_clean_pending_queue(ctlr->lp);
> +		rc = __bnx2fc_disable(ctlr);
>  	}
> -
>  	mutex_unlock(&bnx2fc_dev_lock);
>  	rtnl_unlock();
>  	return rc;
>  }
>  
> +static int __bnx2fc_enable(struct fcoe_ctlr *ctlr)
> +{
> +	struct bnx2fc_interface *interface = fcoe_ctlr_priv(ctlr);
> +
> +	if (interface->enabled == false) {
> +		if (!ctlr->lp) {
> +			pr_err(PFX "__bnx2fc_enable: lport not found\n");
> +			return -ENODEV;
> +		} else if (!bnx2fc_link_ok(ctlr->lp)) {
> +			fcoe_ctlr_link_up(ctlr);
> +			interface->enabled = true;
> +		}
> +	}
> +	return 0;
> +}
> +
>  /**
>   * Deprecated: Use bnx2fc_enabled()
>   */
> @@ -2046,12 +2078,11 @@ static int bnx2fc_enable(struct net_device *netdev)
>  
>  	interface = bnx2fc_interface_lookup(netdev);
>  	ctlr = bnx2fc_to_ctlr(interface);
> -	if (!interface || !ctlr->lp) {
> +	if (!interface) {
>  		rc = -ENODEV;
> -		printk(KERN_ERR PFX "bnx2fc_enable: interface or lport not found\n");
> -	} else if (!bnx2fc_link_ok(ctlr->lp)) {
> -		fcoe_ctlr_link_up(ctlr);
> -		interface->enabled = true;
> +		pr_err(PFX "bnx2fc_enable: interface not found\n");
> +	} else {
> +		rc = __bnx2fc_enable(ctlr);
>  	}
>  
>  	mutex_unlock(&bnx2fc_dev_lock);
> @@ -2072,14 +2103,12 @@ static int bnx2fc_enable(struct net_device *netdev)
>  static int bnx2fc_ctlr_enabled(struct fcoe_ctlr_device *cdev)
>  {
>  	struct fcoe_ctlr *ctlr = fcoe_ctlr_device_priv(cdev);
> -	struct fc_lport *lport = ctlr->lp;
> -	struct net_device *netdev = bnx2fc_netdev(lport);
>  
>  	switch (cdev->enabled) {
>  	case FCOE_CTLR_ENABLED:
> -		return bnx2fc_enable(netdev);
> +		return __bnx2fc_enable(ctlr);
>  	case FCOE_CTLR_DISABLED:
> -		return bnx2fc_disable(netdev);
> +		return __bnx2fc_disable(ctlr);
>  	case FCOE_CTLR_UNUSED:
>  	default:
>  		return -ENOTSUPP;