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Date: Wed, 02 Jan 2008 22:56:24 -0500
From: mbeauch <mbeauch@....net>
To: mingo@...e.hu
Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de
Subject: FW: [PATCH -rt] Preemption problem in kernel RT Patch
Here's the updated patch:
Changed the real-time patch code to detect recursive calls
to dev_queue_xmit and drop the packet when detected.
Signed-off-by: Mark Beauchemin <mark.beauchemin@...amorenet.com>
diff -ru linux-2.6.24-rc5-rt1/include/linux/netdevice.h linux-2.6.24-rc5-rt1-mark/include/linux/netdevice.h
--- linux-2.6.24-rc5-rt1/include/linux/netdevice.h 2007-12-28 09:34:02.000000000 -0500
+++ linux-2.6.24-rc5-rt1-mark/include/linux/netdevice.h 2008-01-01 18:49:49.000000000 -0500
@@ -619,7 +619,7 @@
/* cpu id of processor entered to hard_start_xmit or -1,
if nobody entered there.
*/
- int xmit_lock_owner;
+ void *xmit_lock_owner;
void *priv; /* pointer to private data */
int (*hard_start_xmit) (struct sk_buff *skb,
struct net_device *dev);
@@ -1333,46 +1333,46 @@
*
* Get network device transmit lock
*/
-static inline void __netif_tx_lock(struct net_device *dev, int cpu)
+static inline void __netif_tx_lock(struct net_device *dev)
{
spin_lock(&dev->_xmit_lock);
- dev->xmit_lock_owner = cpu;
+ dev->xmit_lock_owner = (void *)current;
}
static inline void netif_tx_lock(struct net_device *dev)
{
- __netif_tx_lock(dev, raw_smp_processor_id());
+ __netif_tx_lock(dev);
}
static inline void netif_tx_lock_bh(struct net_device *dev)
{
spin_lock_bh(&dev->_xmit_lock);
- dev->xmit_lock_owner = raw_smp_processor_id();
+ dev->xmit_lock_owner = (void *)current;
}
static inline int netif_tx_trylock(struct net_device *dev)
{
int ok = spin_trylock(&dev->_xmit_lock);
if (likely(ok))
- dev->xmit_lock_owner = raw_smp_processor_id();
+ dev->xmit_lock_owner = (void *)current;
return ok;
}
static inline void netif_tx_unlock(struct net_device *dev)
{
- dev->xmit_lock_owner = -1;
+ dev->xmit_lock_owner = (void *)-1;
spin_unlock(&dev->_xmit_lock);
}
static inline void netif_tx_unlock_bh(struct net_device *dev)
{
- dev->xmit_lock_owner = -1;
+ dev->xmit_lock_owner = (void *)-1;
spin_unlock_bh(&dev->_xmit_lock);
}
-#define HARD_TX_LOCK(dev, cpu) { \
+#define HARD_TX_LOCK(dev) { \
if ((dev->features & NETIF_F_LLTX) == 0) { \
- __netif_tx_lock(dev, cpu); \
+ __netif_tx_lock(dev); \
} \
}
diff -ru linux-2.6.24-rc5-rt1/net/core/dev.c linux-2.6.24-rc5-rt1-mark/net/core/dev.c
--- linux-2.6.24-rc5-rt1/net/core/dev.c 2007-12-28 09:34:01.000000000 -0500
+++ linux-2.6.24-rc5-rt1-mark/net/core/dev.c 2008-01-01 18:48:33.000000000 -0500
@@ -1692,18 +1692,10 @@
Either shot noqueue qdisc, it is even simpler 8)
*/
if (dev->flags & IFF_UP) {
- int cpu = raw_smp_processor_id(); /* ok because BHs are off */
- /*
- * No need to check for recursion with threaded interrupts:
- */
-#ifdef CONFIG_PREEMPT_RT
- if (1) {
-#else
- if (dev->xmit_lock_owner != cpu) {
-#endif
+ if (dev->xmit_lock_owner != (void *)current) {
- HARD_TX_LOCK(dev, cpu);
+ HARD_TX_LOCK(dev);
if (!netif_queue_stopped(dev) &&
!netif_subqueue_stopped(dev, skb)) {
@@ -3630,7 +3622,7 @@
spin_lock_init(&dev->queue_lock);
spin_lock_init(&dev->_xmit_lock);
netdev_set_lockdep_class(&dev->_xmit_lock, dev->type);
- dev->xmit_lock_owner = -1;
+ dev->xmit_lock_owner = (void *)-1;
spin_lock_init(&dev->ingress_lock);
dev->iflink = -1;
diff -ru linux-2.6.24-rc5-rt1/net/sched/sch_generic.c linux-2.6.24-rc5-rt1-mark/net/sched/sch_generic.c
--- linux-2.6.24-rc5-rt1/net/sched/sch_generic.c 2007-12-28 09:34:02.000000000 -0500
+++ linux-2.6.24-rc5-rt1-mark/net/sched/sch_generic.c 2008-01-01 18:52:33.000000000 -0500
@@ -89,7 +89,7 @@
{
int ret;
- if (unlikely(dev->xmit_lock_owner == raw_smp_processor_id())) {
+ if (unlikely(dev->xmit_lock_owner == (void *)current)) {
/*
* Same CPU holding the lock. It may be a transient
* configuration error, when hard_start_xmit() recurses. We
@@ -146,7 +146,7 @@
/* And release queue */
spin_unlock(&dev->queue_lock);
- HARD_TX_LOCK(dev, raw_smp_processor_id());
+ HARD_TX_LOCK(dev);
if (!netif_subqueue_stopped(dev, skb))
ret = dev_hard_start_xmit(skb, dev);
HARD_TX_UNLOCK(dev);
--
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