Re: [PATCH] bnx2fc:Add proper locking protection in bnx2fc_ctrlr_enabled

Re: [PATCH] bnx2fc:Add proper locking protection in bnx2fc_ctrlr_enabled

[Chad Dupuis]

On Sat, 12 Dec 2015, Nicholas Krause wrote:

> This adds proper locking protection in bnx2fc_ctrl_enabled around
> the calls to the functions, _bnx2fc_enable and _bnx2fc_disable in
> order to avoid concurrent access on these functions accessing global
> referenced data structures in their internal intended work.
>
> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
> ---
> drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> index 67405c6..e43648f 100644
> --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> @@ -2177,13 +2177,21 @@ static int bnx2fc_ctlr_enabled(struct fcoe_ctlr_device *cdev)
> {
> 	struct fcoe_ctlr *ctlr = fcoe_ctlr_device_priv(cdev);
>
> +	rtnl_lock();
> +	mutex_lock(&bnx2fc_dev_lock);
> 	switch (cdev->enabled) {
> 	case FCOE_CTLR_ENABLED:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return __bnx2fc_enable(ctlr);
> 	case FCOE_CTLR_DISABLED:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return __bnx2fc_disable(ctlr);
> 	case FCOE_CTLR_UNUSED:
> 	default:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return -ENOTSUPP;
> 	};
> }
>

Nack.  All we end up protecting is the check of cdev->enabled and I do not 
believe taking two mutexes is required for that.

RE: [PATCH] bnx2fc:Add proper locking protection in bnx2fc_ctrlr_enabled

[Joe Carnuccio]

Also, the patch fails to do what it's message describes, i.e. the calls _bnx2fc_enable() and _bnx2fc_disable() are outside the lock/unlock.


-----Original Message-----
From: Chad Dupuis 
Sent: Tuesday, December 15, 2015 8:43 AM
To: Nicholas Krause <xerofoify@gmail.com>
Cc: Dept-Eng QLogic Storage Upstream <QLogic-Storage-Upstream@qlogic.com>; JBottomley@odin.com; martin.petersen@oracle.com; linux-scsi <linux-scsi@vger.kernel.org>; linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] bnx2fc:Add proper locking protection in bnx2fc_ctrlr_enabled


On Sat, 12 Dec 2015, Nicholas Krause wrote:

> This adds proper locking protection in bnx2fc_ctrl_enabled around the 
> calls to the functions, _bnx2fc_enable and _bnx2fc_disable in order to 
> avoid concurrent access on these functions accessing global referenced 
> data structures in their internal intended work.
>
> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
> ---
> drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c 
> b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> index 67405c6..e43648f 100644
> --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> @@ -2177,13 +2177,21 @@ static int bnx2fc_ctlr_enabled(struct 
> fcoe_ctlr_device *cdev) {
> 	struct fcoe_ctlr *ctlr = fcoe_ctlr_device_priv(cdev);
>
> +	rtnl_lock();
> +	mutex_lock(&bnx2fc_dev_lock);
> 	switch (cdev->enabled) {
> 	case FCOE_CTLR_ENABLED:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return __bnx2fc_enable(ctlr);
> 	case FCOE_CTLR_DISABLED:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return __bnx2fc_disable(ctlr);
> 	case FCOE_CTLR_UNUSED:
> 	default:
> +		rtnl_unlock();
> +		mutex_unlock(&bnx2fc_dev_lock);
> 		return -ENOTSUPP;
> 	};
> }
>

Nack.  All we end up protecting is the check of cdev->enabled and I do not believe taking two mutexes is required for that.