netdev - [PATCH net-next 11/23] tipc: Revise comment justifying release of configuration spinlock

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Date:	Tue, 27 Dec 2011 12:39:30 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, allan.stephens@...driver.com,
	ying.xue@...driver.com,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [PATCH net-next 11/23] tipc: Revise comment justifying release of configuration spinlock

From: Allan Stephens <allan.stephens@...driver.com>

Comment-only change to better explain why TIPC's configuration lock is
temporarily released while activating support for network interfaces,
and why the existing activation code doesn't require rework.

Signed-off-by: Allan Stephens <allan.stephens@...driver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 net/tipc/config.c |   13 ++++++-------
 1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/net/tipc/config.c b/net/tipc/config.c
index b25a396..4785bf2 100644
--- a/net/tipc/config.c
+++ b/net/tipc/config.c
@@ -184,13 +184,12 @@ static struct sk_buff *cfg_set_own_addr(void)
 						   " (cannot change node address once assigned)");
 
 	/*
-	 * Must release all spinlocks before calling start_net() because
-	 * Linux version of TIPC calls eth_media_start() which calls
-	 * register_netdevice_notifier() which may block!
-	 *
-	 * Temporarily releasing the lock should be harmless for non-Linux TIPC,
-	 * but Linux version of eth_media_start() should really be reworked
-	 * so that it can be called with spinlocks held.
+	 * Must temporarily release configuration spinlock while switching into
+	 * networking mode as it calls tipc_eth_media_start(), which may sleep.
+	 * Releasing the lock is harmless as other locally-issued configuration
+	 * commands won't occur until this one completes, and remotely-issued
+	 * configuration commands can't be received until a local configuration
+	 * command to enable the first bearer is received and processed.
 	 */
 
 	spin_unlock_bh(&config_lock);
-- 
1.7.4.4

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