lkml.org 
[lkml]   [2022]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH 3/3] drivers/net/ftgmac100: fix DHCP potential failure with systemd
From


On 2/23/2022 3:39 AM, Heyi Guo wrote:
> Hi Florian,
>
> 在 2022/2/23 下午1:00, Florian Fainelli 写道:
>>
>>
>> On 2/22/2022 7:14 PM, Heyi Guo wrote:
>>> DHCP failures were observed with systemd 247.6. The issue could be
>>> reproduced by rebooting Aspeed 2600 and then running ifconfig ethX
>>> down/up.
>>>
>>> It is caused by below procedures in the driver:
>>>
>>> 1. ftgmac100_open() enables net interface and call phy_start()
>>> 2. When PHY is link up, it calls netif_carrier_on() and then
>>> adjust_link callback
>>> 3. ftgmac100_adjust_link() will schedule the reset task
>>> 4. ftgmac100_reset_task() will then reset the MAC in another schedule
>>>
>>> After step 2, systemd will be notified to send DHCP discover packet,
>>> while the packet might be corrupted by MAC reset operation in step 4.
>>>
>>> Call ftgmac100_reset() directly instead of scheduling task to fix the
>>> issue.
>>>
>>> Signed-off-by: Heyi Guo <guoheyi@linux.alibaba.com>
>>> ---
>>> Cc: Andrew Lunn <andrew@lunn.ch>
>>> Cc: "David S. Miller" <davem@davemloft.net>
>>> Cc: Jakub Kicinski <kuba@kernel.org>
>>> Cc: Joel Stanley <joel@jms.id.au>
>>> Cc: Guangbin Huang <huangguangbin2@huawei.com>
>>> Cc: Hao Chen <chenhao288@hisilicon.com>
>>> Cc: Arnd Bergmann <arnd@arndb.de>
>>> Cc: Dylan Hung <dylan_hung@aspeedtech.com>
>>> Cc: netdev@vger.kernel.org
>>>
>>>
>>> ---
>>>   drivers/net/ethernet/faraday/ftgmac100.c | 13 +++++++++++--
>>>   1 file changed, 11 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/ethernet/faraday/ftgmac100.c
>>> b/drivers/net/ethernet/faraday/ftgmac100.c
>>> index c1deb6e5d26c5..d5356db7539a4 100644
>>> --- a/drivers/net/ethernet/faraday/ftgmac100.c
>>> +++ b/drivers/net/ethernet/faraday/ftgmac100.c
>>> @@ -1402,8 +1402,17 @@ static void ftgmac100_adjust_link(struct
>>> net_device *netdev)
>>>       /* Disable all interrupts */
>>>       iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);
>>>   -    /* Reset the adapter asynchronously */
>>> -    schedule_work(&priv->reset_task);
>>> +    /* Release phy lock to allow ftgmac100_reset to aquire it,
>>> keeping lock
>>
>> typo: acquire
>>
> Thanks for the catch :)
>>> +     * order consistent to prevent dead lock.
>>> +     */
>>> +    if (netdev->phydev)
>>> +        mutex_unlock(&netdev->phydev->lock);
>>> +
>>> +    ftgmac100_reset(priv);
>>> +
>>> +    if (netdev->phydev)
>>> +        mutex_lock(&netdev->phydev->lock);
>>
>> Do you really need to perform a full MAC reset whenever the link goes
>> up or down? Instead cannot you just extract the maccr configuration
>> which adjusts the speed and be done with it?
>
> This is the original behavior and not changed in this patch set, and I'm
> not familiar with the hardware design of ftgmac100, so I'd like to limit
> the changes to the code which really causes practical issues.

This unlocking and re-locking seems superfluous when you could introduce
a version of ftgmac100_reset() which does not acquire the PHY device
mutex, and have that version called from ftgmac100_adjust_link(). For
every other call site, you would acquire it. Something like this for
instance:


diff --git a/drivers/net/ethernet/faraday/ftgmac100.c
b/drivers/net/ethernet/faraday/ftgmac100.c
index 691605c15265..98179c3fd9ee 100644
--- a/drivers/net/ethernet/faraday/ftgmac100.c
+++ b/drivers/net/ethernet/faraday/ftgmac100.c
@@ -1038,7 +1038,7 @@ static void ftgmac100_adjust_link(struct
net_device *netdev)
iowrite32(0, priv->base + FTGMAC100_OFFSET_IER);

/* Reset the adapter asynchronously */
- schedule_work(&priv->reset_task);
+ ftgmac100_reset(priv, false);
}

static int ftgmac100_mii_probe(struct net_device *netdev)
@@ -1410,10 +1410,8 @@ static int ftgmac100_init_all(struct ftgmac100
*priv, bool ignore_alloc_err)
return err;
}

-static void ftgmac100_reset_task(struct work_struct *work)
+static void ftgmac100_reset_task(struct ftgmac100_priv *priv, bool
lock_phy)
{
- struct ftgmac100 *priv = container_of(work, struct ftgmac100,
- reset_task);
struct net_device *netdev = priv->netdev;
int err;

@@ -1421,7 +1419,7 @@ static void ftgmac100_reset_task(struct
work_struct *work)

/* Lock the world */
rtnl_lock();
- if (netdev->phydev)
+ if (netdev->phydev && lock_phy)
mutex_lock(&netdev->phydev->lock);
if (priv->mii_bus)
mutex_lock(&priv->mii_bus->mdio_lock);
@@ -1454,11 +1452,19 @@ static void ftgmac100_reset_task(struct
work_struct *work)
bail:
if (priv->mii_bus)
mutex_unlock(&priv->mii_bus->mdio_lock);
- if (netdev->phydev)
+ if (netdev->phydev && lock_phy)
mutex_unlock(&netdev->phydev->lock);
rtnl_unlock();
}

+static void ftgmac100_reset_task(struct work_struct *work)
+{
+ struct ftgmac100 *priv = container_of(work, struct ftgmac100,
+ reset_task);
+
+ ftgmac100_reset(priv, true);
+}
+
static int ftgmac100_open(struct net_device *netdev)
{
struct ftgmac100 *priv = netdev_priv(netdev)
--
Florian
\
 
 \ /
  Last update: 2022-02-23 18:56    [W:0.083 / U:0.756 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site