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From: Roland Dreier <rdreier@cisco.com>
To: Andrew Morton <akpm@osdl.org>, mst@mellanox.co.il
Cc: Roland Dreier <rolandd@cisco.com>,
	linux-kernel@vger.kernel.org, openib-general@openib.org
Subject: Re: [git patch review 1/4] IPoIB: Don't start send-only joins while multicast thread is stopped
Date: Sat, 11 Feb 2006 18:03:18 -0800	[thread overview]
Message-ID: <ada8xsh49ll.fsf@cisco.com> (raw)
In-Reply-To: <20060211140209.57af1b16.akpm@osdl.org> (Andrew Morton's message of "Sat, 11 Feb 2006 14:02:09 -0800")

 > Roland Dreier <rolandd@cisco.com> wrote:
 > >
 > >  +	spin_lock_irq(&priv->lock);
 > >  +	set_bit(IPOIB_MCAST_STARTED, &priv->flags);
 > >  +	spin_unlock_irq(&priv->lock);
 > 
 > Strange to put a lock around an atomic op like that.
 > 
 > Sometimes it's valid.   If another cpu was doing:
 > 
 > 	spin_lock(lock);
 > 
 > 	if (test_bit(IPOIB_MCAST_STARTED))
 > 		something();
 > 	...
 > 	if (test_bit(IPOIB_MCAST_STARTED))
 > 		something_else();
 > 
 > 	spin_unlock(lock);
 > 
 > then the locked set_bit() makes sense.
 > 
 > But often it doesn't ;)

Good point.  Michael, any reason why the lock is there around the
set_bit()?  (And similarly for the corresponding clear_bit())

Thanks,
 Roland

  reply	other threads:[~2006-02-12  2:03 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-11 20:22 [git patch review 1/4] IPoIB: Don't start send-only joins while multicast thread is stopped Roland Dreier
2006-02-11 20:22 ` [git patch review 2/4] IPoIB: Fix another send-only join race Roland Dreier
2006-02-11 20:22   ` [git patch review 3/4] IB/mthca: Don't print debugging info until we have all values Roland Dreier
2006-02-11 20:22     ` [git patch review 4/4] IPoIB: Yet another fix for send-only joins Roland Dreier
2006-02-11 22:02 ` [git patch review 1/4] IPoIB: Don't start send-only joins while multicast thread is stopped Andrew Morton
2006-02-12  2:03   ` Roland Dreier [this message]
2006-02-12  7:50     ` [openib-general] " Michael S. Tsirkin
2006-02-12  8:13       ` Kyle Moffett
2006-02-12  8:19         ` Michael S. Tsirkin
2006-02-12 16:37       ` [openib-general] " Roland Dreier
2006-02-12 16:56         ` Michael S. Tsirkin

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