* Re: [RFC PATCH] unlock rtnl mutex in ic_open_devs while waiting
2015-01-06 22:21 ` David Miller
@ 2015-01-07 10:06 ` Maarten Lankhorst
0 siblings, 0 replies; 3+ messages in thread
From: Maarten Lankhorst @ 2015-01-07 10:06 UTC (permalink / raw)
To: David Miller
Cc: kuznet, jmorris, yoshfuji, kaber, netdev, linux-kernel,
Jay Cliburn, Chris Snook, Sabrina Dubroca, Johannes Berg
Op 06-01-15 om 23:21 schreef David Miller:
> From: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> Date: Mon, 05 Jan 2015 14:52:06 +0100
>
>> This fixes a deadlock with alx_link_check, which takes the rtnl_mutex in
>> a work item to check the link.
>>
>> I have no idea whether alx should be fixed or ipconfig.c,
>> but this saves 120 seconds off my boot time. ;-)
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
> I genuinely think that alx_link_check() needs to use a smaller hammer
> to do it's locking, there is no reason to use the RTNL mutex.
>
> A driver private mutex will probably work just as well and not have
> this problem.
I guess alx_check_link uses the rtnl_lock for serializing against any possible alx_reset call.
The alternative is stopping check_link work before running anything that changes the device state.
Does the below patch look sane instead?
---
diff --git a/drivers/net/ethernet/atheros/alx/alx.h b/drivers/net/ethernet/atheros/alx/alx.h
index 8fc93c5f6abc..354f155b3144 100644
--- a/drivers/net/ethernet/atheros/alx/alx.h
+++ b/drivers/net/ethernet/atheros/alx/alx.h
@@ -88,6 +88,8 @@ struct alx_priv {
unsigned int size;
} descmem;
+ bool stop_link_check;
+
/* protect int_mask updates */
spinlock_t irq_lock;
u32 int_mask;
diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c
index e398eda07298..ae93b8052cbf 100644
--- a/drivers/net/ethernet/atheros/alx/main.c
+++ b/drivers/net/ethernet/atheros/alx/main.c
@@ -315,7 +316,8 @@ static irqreturn_t alx_intr_handle(struct alx_priv *alx, u32 intr)
*/
alx->int_mask &= ~ALX_ISR_PHY;
write_int_mask = true;
- alx_schedule_link_check(alx);
+ if (!alx->stop_link_check)
+ alx_schedule_link_check(alx);
}
if (intr & (ALX_ISR_TX_Q0 | ALX_ISR_RX_Q0)) {
@@ -742,6 +744,17 @@ static netdev_features_t alx_fix_features(struct net_device *netdev,
return features;
}
+static void alx_disable_link_check(struct alx_priv *alx)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&alx->irq_lock, flags);
+ alx->stop_link_check = true;
+ spin_unlock_irqrestore(&alx->irq_lock, flags);
+
+ cancel_work_sync(&alx->link_check_wk);
+}
+
static void alx_netif_stop(struct alx_priv *alx)
{
alx->dev->trans_start = jiffies;
@@ -756,6 +769,7 @@ static void alx_halt(struct alx_priv *alx)
{
struct alx_hw *hw = &alx->hw;
+ alx_disable_link_check(alx);
alx_netif_stop(alx);
hw->link_speed = SPEED_UNKNOWN;
hw->duplex = DUPLEX_UNKNOWN;
@@ -788,6 +802,7 @@ static void alx_activate(struct alx_priv *alx)
/* clear old interrupts */
alx_write_mem32(&alx->hw, ALX_ISR, ~(u32)ALX_ISR_DIS);
+ alx->stop_link_check = false;
alx_irq_enable(alx);
alx_schedule_link_check(alx);
@@ -850,6 +865,7 @@ static int __alx_open(struct alx_priv *alx, bool resume)
/* clear old interrupts */
alx_write_mem32(&alx->hw, ALX_ISR, ~(u32)ALX_ISR_DIS);
+ alx->stop_link_check = false;
alx_irq_enable(alx);
if (!resume)
@@ -966,9 +982,7 @@ static void alx_link_check(struct work_struct *work)
alx = container_of(work, struct alx_priv, link_check_wk);
- rtnl_lock();
alx_check_link(alx);
- rtnl_unlock();
}
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