To: "Bryan O'Sullivan" <bos@pathscale.com>
Cc: rolandd@cisco.com, gregkh@suse.de, akpm@osdl.org, davem@davemloft.net,
       linux-kernel@vger.kernel.org, openib-general@openib.org
Subject: Re: [PATCH 9 of 20] ipath - char devices for diagnostics and lightweight subnet management
References: <eac2ad3017b5f160d24c.1141922822@localhost.localdomain>
From: Roland Dreier <rdreier@cisco.com>
Date: Thu, 09 Mar 2006 15:26:43 -0800
In-Reply-To: <eac2ad3017b5f160d24c.1141922822@localhost.localdomain> (Bryan O'Sullivan's message of "Thu,  9 Mar 2006 08:47:02 -0800")
Message-ID: <ada8xrjfbd8.fsf@cisco.com>
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 > +static int ipath_sma_release(struct inode *in, struct file *fp)
 > +{
 > +	int s;
 > +
 > +	ipath_sma_alive = 0;
 > +	ipath_cdbg(SMA, "Closing SMA device\n");
 > +	for (s = 0; s < atomic_read(&ipath_max); s++) {
 > +		struct ipath_devdata *dd = ipath_lookup(s);
 > +
 > +		if (!dd || !(dd->ipath_flags & IPATH_INITTED))
 > +			continue;
 > +		*dd->ipath_statusp &= ~IPATH_STATUS_SMA;
 > +		if (dd->verbs_layer.l_flags & IPATH_VERBS_KERNEL_SMA)
 > +			*dd->ipath_statusp |= IPATH_STATUS_OIB_SMA;
 > +	}
 > +	return 0;
 > +}

Similarly what protects against another process opening the device
right after the ipath_sma_alive = 0 setting, but before you do all the
cleanup that's after that?

And what protects against a hot unplug of a device after the test of s
against ipath_max?

 - R.
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