netdev - Re: [PATCH] 3c59x: Remove atomic context inside vortex_{set|get}

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Date:	Wed, 15 Sep 2010 08:35:17 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Denis Kirjanov <dkirjanov@...nel.org>
Cc:	davem@...emloft.net, andrew@...displaytech.com,
	ben@...adent.org.uk, netdev@...r.kernel.org
Subject: Re: [PATCH] 3c59x: Remove atomic context inside
 vortex_{set|get}_wol

Le mercredi 15 septembre 2010 à 06:24 +0000, Denis Kirjanov a écrit :
> There is no need to use spinlocks in vortex_{set|get}_wol.
> This also fixes a bug:
> [  254.214993] 3c59x 0000:00:0d.0: PME# enabled
> [  254.215021] BUG: sleeping function called from invalid context at kernel/mutex.c:94
> [  254.215030] in_atomic(): 0, irqs_disabled(): 1, pid: 4875, name: ethtool
> [  254.215042] Pid: 4875, comm: ethtool Tainted: G        W   2.6.36-rc3+ #7
> [  254.215049] Call Trace:
> [  254.215050]  [] __might_sleep+0xb1/0xb6
> [  254.215050]  [] mutex_lock+0x17/0x30
> [  254.215050]  [] acpi_enable_wakeup_device_power+0x2b/0xb1
> [  254.215050]  [] acpi_pm_device_sleep_wake+0x42/0x7f
> [  254.215050]  [] acpi_pci_sleep_wake+0x5d/0x63
> [  254.215050]  [] platform_pci_sleep_wake+0x1d/0x20
> [  254.215050]  [] __pci_enable_wake+0x90/0xd0
> [  254.215050]  [] acpi_set_WOL+0x8e/0xf5 [3c59x]
> [  254.215050]  [] vortex_set_wol+0x4e/0x5e [3c59x]
> [  254.215050]  [] dev_ethtool+0x1cf/0xb61
> [  254.215050]  [] ? debug_mutex_free_waiter+0x45/0x4a
> [  254.215050]  [] ? __mutex_lock_common+0x204/0x20e
> [  254.215050]  [] ? __mutex_lock_slowpath+0x12/0x15
> [  254.215050]  [] ? mutex_lock+0x23/0x30
> [  254.215050]  [] dev_ioctl+0x42c/0x533
> [  254.215050]  [] ? _cond_resched+0x8/0x1c
> [  254.215050]  [] ? lock_page+0x1c/0x30
> [  254.215050]  [] ? page_address+0x15/0x7c
> [  254.215050]  [] ? filemap_fault+0x187/0x2c4
> [  254.215050]  [] sock_ioctl+0x1d4/0x1e0
> [  254.215050]  [] ? sock_ioctl+0x0/0x1e0
> [  254.215050]  [] vfs_ioctl+0x19/0x33
> [  254.215050]  [] do_vfs_ioctl+0x424/0x46f
> [  254.215050]  [] ? selinux_file_ioctl+0x3c/0x40
> [  254.215050]  [] sys_ioctl+0x40/0x5a
> [  254.215050]  [] sysenter_do_call+0x12/0x22
> 
> vortex_set_wol protected with a spinlock, but nested  acpi_set_WOL acquires a mutex inside atomic context.
> Ethtool operations are already serialized by RTNL mutex, so it is safe to drop the locks.
> 
> Signed-off-by: Denis Kirjanov <dkirjanov@...nel.org>
> ---
>  drivers/net/3c59x.c |    6 ++----
>  1 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/3c59x.c b/drivers/net/3c59x.c
> index 7a01588..a5c697b 100644
> --- a/drivers/net/3c59x.c
> +++ b/drivers/net/3c59x.c
> @@ -634,6 +634,8 @@ struct vortex_private {
>  		medialock:1,
>  		must_free_region:1,				/* Flag: if zero, Cardbus owns the I/O region */
>  		large_frames:1;			/* accept large frames */
> +	/* {get|set}_wol operations are already serialized by rtnl.
> +	 * no additional locking is required for the enable_wol and acpi_set_WOL() */

Please format this comment like this :

	/* This is a fine ............................
	 * and long comment ..................................
	 */

>  	int drv_flags;
>  	u16 status_enable;
>  	u16 intr_enable;
> @@ -2922,13 +2924,11 @@ static void vortex_get_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
>  {
>  	struct vortex_private *vp = netdev_priv(dev);
>  
> -	spin_lock_irq(&vp->lock);
>  	wol->supported = WAKE_MAGIC;
>  
>  	wol->wolopts = 0;
>  	if (vp->enable_wol)
>  		wol->wolopts |= WAKE_MAGIC;
> -	spin_unlock_irq(&vp->lock);
>  }
>  
>  static int vortex_set_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
> @@ -2937,13 +2937,11 @@ static int vortex_set_wol(struct net_device *dev, struct ethtool_wolinfo *wol)
>  	if (wol->wolopts & ~WAKE_MAGIC)
>  		return -EINVAL;
>  
> -	spin_lock_irq(&vp->lock);
>  	if (wol->wolopts & WAKE_MAGIC)
>  		vp->enable_wol = 1;
>  	else
>  		vp->enable_wol = 0;
>  	acpi_set_WOL(dev);
> -	spin_unlock_irq(&vp->lock);
>  
>  	return 0;
>  }


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