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-rw-r--r--features/rt/net-Remove-preemption-disabling-in-netif_rx.patch67
1 files changed, 67 insertions, 0 deletions
diff --git a/features/rt/net-Remove-preemption-disabling-in-netif_rx.patch b/features/rt/net-Remove-preemption-disabling-in-netif_rx.patch
new file mode 100644
index 00000000..b92de5fc
--- /dev/null
+++ b/features/rt/net-Remove-preemption-disabling-in-netif_rx.patch
@@ -0,0 +1,67 @@
+From efa7c96f4b8dec2a51711a6eef658093b42a6d91 Mon Sep 17 00:00:00 2001
+From: Priyanka Jain <Priyanka.Jain@freescale.com>
+Date: Thu, 17 May 2012 09:35:11 +0530
+Subject: [PATCH 150/191] net: 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.
+
+-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@freescale.com>
+Acked-by: Rajan Srivastava <Rajan.Srivastava@freescale.com>
+Cc: <rostedt@goodmis.orgn>
+Link: http://lkml.kernel.org/r/1337227511-2271-1-git-send-email-Priyanka.Jain@freescale.com
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+[bigeasy: Remove assumption about migrate_disable() from the description.]
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ net/core/dev.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/net/core/dev.c b/net/core/dev.c
+index 52c928940167..ca150f02eed1 100644
+--- a/net/core/dev.c
++++ b/net/core/dev.c
+@@ -4837,7 +4837,7 @@ static int netif_rx_internal(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);
+@@ -4847,14 +4847,14 @@ static int netif_rx_internal(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;
+ }
+--
+2.19.1
+