Thread (21 messages) flat view 21 messages, 3 authors, 2012-08-25

Re: [PATCH 14/15] netpoll: re-enable irq in poll_napi()

From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-08-24 19:43:35

On Fri, 10 Aug 2012 19:24:50 +0800
Cong Wang [off-list ref] wrote:
quoted hunk ↗ jump to hunk
napi->poll() needs IRQ enabled, so we have to re-enable IRQ before
calling it.

Cc: David Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <redacted>
---
 net/core/netpoll.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index e4ba3e7..346b1eb 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -168,16 +168,24 @@ static void poll_napi(struct net_device *dev)
 	struct napi_struct *napi;
 	int budget = 16;
 
+	WARN_ON_ONCE(!irqs_disabled());
+
 	list_for_each_entry(napi, &dev->napi_list, dev_list) {
+		local_irq_enable();
 		if (napi->poll_owner != smp_processor_id() &&
 		    spin_trylock(&napi->poll_lock)) {
+			rcu_read_lock_bh();
 			budget = poll_one_napi(rcu_dereference_bh(dev->npinfo),
 					       napi, budget);
+			rcu_read_unlock_bh();
 			spin_unlock(&napi->poll_lock);
 
-			if (!budget)
+			if (!budget) {
+				local_irq_disable();
 				break;
+			}
 		}
+		local_irq_disable();
 	}
 }
This commit (6bdb7fe3104 in mainline) makes my netconsole-using x86_64
box lock up during boot.  Dunno why, but I do have a cellphone:
http://ozlabs.org/~akpm/stuff/IMG_20120824_122054.jpg
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