Waiting for review comments on this.
Thanks
Priyanka
-----Original Message-----
From: Jain Priyanka-B32167
Sent: Thursday, May 17, 2012 9:35 AM
To: linux-rt-users@xxxxxxxxxxxxxxx
Cc: tglx@xxxxxxxxxxxxx; rostedt@xxxxxxxxxxxx; Srivastava Rajan-B34330; Jain Priyanka-B32167
Subject: [PATCH][UPSTREAM]net,RT:Remove preemption disabling in netif_rx()
1)enqueue_to_backlog() (called from netif_rx) should be
bind to a particluar CPU. This can be achieved by
disabling migration. No need to disable preemption
2)Fixes crash "BUG: scheduling while atomic: ksoftirqd"
in case of RT.
If preemption is disabled, enqueue_to_backog() is called
in atomic context. And if backlog exceeds its count,
kfree_skb() is called. But in RT, kfree_skb() might
gets scheduled out, so it expects non atomic context.
3)When CONFIG_PREEMPT_RT_FULL is not defined, migrate_enable(), migrate_disable() maps to
preempt_enable() and preempt_disable(), so no change in functionality in case of non-RT.
-Replace preempt_enable(), preempt_disable() with migrate_enable(), migrate_disable() respectively -Replace get_cpu(), put_cpu() with get_cpu_light(),
put_cpu_light() respectively
Signed-off-by: Priyanka Jain <Priyanka.Jain@xxxxxxxxxxxxx>
Acked-by: Rajan Srivastava <Rajan.Srivastava@xxxxxxxxxxxxx>
---
Testing: Tested successfully on p4080ds(8-core SMP system)
net/core/dev.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c index 452db70..4017820 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2940,7 +2940,7 @@ int netif_rx(struct sk_buff *skb)
struct rps_dev_flow voidflow, *rflow = &voidflow;
int cpu;
- preempt_disable();
+ migrate_disable();
rcu_read_lock();
cpu = get_rps_cpu(skb->dev, skb, &rflow); @@ -2950,13 +2950,13 @@ int netif_rx(struct sk_buff *skb)
ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
rcu_read_unlock();
- preempt_enable();
+ migrate_enable();
} else
#endif
{
unsigned int qtail;
- ret = enqueue_to_backlog(skb, get_cpu(), &qtail);
- put_cpu();
+ ret = enqueue_to_backlog(skb, get_cpu_light(), &qtail);
+ put_cpu_light();
}
return ret;
}
--
1.7.4.1
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
