netdev - [PATCHv4 RFC 3/4] sparc64: Avoid irqsave/restore on vio.lock if in

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Message-ID: <20141015180240.GJ11840@oracle.com>
Date:	Wed, 15 Oct 2014 14:02:40 -0400
From:	Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:	davem@...emloft.net, sowmini.varadhan@...cle.com
Cc:	netdev@...r.kernel.org, sparclinux@...r.kernel.org
Subject: [PATCHv4 RFC 3/4] sparc64: Avoid irqsave/restore on vio.lock if
 in_softirq()

For NAPIfied drivers , there is no need to
synchronize by doing irqsave/restore on vio.lock in the I/O
path.

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@...cle.com>
---
 arch/sparc/kernel/viohs.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/sparc/kernel/viohs.c b/arch/sparc/kernel/viohs.c
index 7ef081a..d731586 100644
--- a/arch/sparc/kernel/viohs.c
+++ b/arch/sparc/kernel/viohs.c
@@ -747,10 +747,11 @@ EXPORT_SYMBOL(vio_ldc_free);
 
 void vio_port_up(struct vio_driver_state *vio)
 {
-	unsigned long flags;
+	unsigned long flags = 0;
 	int err, state;
 
-	spin_lock_irqsave(&vio->lock, flags);
+	if (!in_softirq())
+		spin_lock_irqsave(&vio->lock, flags);
 
 	state = ldc_state(vio->lp);
 
@@ -777,7 +778,8 @@ void vio_port_up(struct vio_driver_state *vio)
 		mod_timer(&vio->timer, expires);
 	}
 
-	spin_unlock_irqrestore(&vio->lock, flags);
+	if (!in_softirq())
+		spin_unlock_irqrestore(&vio->lock, flags);
 }
 EXPORT_SYMBOL(vio_port_up);
 
-- 
1.8.4.2

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