linux-kernel - [PATCH] pcmcia: Fix broken abuse of dev->driver

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Date:	Mon, 22 Sep 2008 15:58:14 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	torvalds@...l.org, linux-kernel@...r.kernel.org
Subject: [PATCH] pcmcia: Fix broken abuse of dev->driver_data

From: Alan Cox <alan@...hat.com>

PCMCIA abuses dev->private_data in the probe methods. Unfortunately it
continues to abuse it after calling drv->probe() which leads to crashes and
other nasties (such as bogus probes of multifunction devices) giving errors like

pcmcia: registering new device pcmcia0.1
kernel: 0.1: GetNextTuple: No more items

Extract the passed data before calling the driver probe function that way
we don't blow up when the driver reuses dev->private_data as its right.

As its close to the final release just move the hack so it works out,
hopefully someone will be sufficiently embarrassed to produce a nice rework
for 2.6.28.

Signed-off-by: Alan Cox <alan@...hat.com>
---

 drivers/pcmcia/ds.c |   23 ++++++++++++++---------
 1 files changed, 14 insertions(+), 9 deletions(-)


diff --git a/drivers/pcmcia/ds.c b/drivers/pcmcia/ds.c
index 4174d96..853d342 100644
--- a/drivers/pcmcia/ds.c
+++ b/drivers/pcmcia/ds.c
@@ -426,6 +426,18 @@ static int pcmcia_device_probe(struct device * dev)
 	p_dev = to_pcmcia_dev(dev);
 	p_drv = to_pcmcia_drv(dev->driver);
 	s = p_dev->socket;
+	
+	/* The PCMCIA code passes the match data in via dev->driver_data
+	 * which is an ugly hack. Once the driver probe is called it may
+	 * and often will overwrite the match data so we must save it first 
+	 *
+	 * handle pseudo multifunction devices:
+	 * there are at most two pseudo multifunction devices.
+	 * if we're matching against the first, schedule a
+	 * call which will then check whether there are two
+	 * pseudo devices, and if not, add the second one.
+	 */
+	did = p_dev->dev.driver_data;
 
 	ds_dbg(1, "trying to bind %s to %s\n", p_dev->dev.bus_id,
 	       p_drv->drv.name);
@@ -455,21 +467,14 @@ static int pcmcia_device_probe(struct device * dev)
 		goto put_module;
 	}
 
-	/* handle pseudo multifunction devices:
-	 * there are at most two pseudo multifunction devices.
-	 * if we're matching against the first, schedule a
-	 * call which will then check whether there are two
-	 * pseudo devices, and if not, add the second one.
-	 */
-	did = p_dev->dev.driver_data;
 	if (did && (did->match_flags & PCMCIA_DEV_ID_MATCH_DEVICE_NO) &&
 	    (p_dev->socket->device_count == 1) && (p_dev->device_no ==
0)) pcmcia_add_device_later(p_dev->socket, 0);
 
- put_module:
+put_module:
 	if (ret)
 		module_put(p_drv->owner);
- put_dev:
+put_dev:
 	if (ret)
 		put_device(dev);
 	return (ret);
--
<meme>discombobulated echidna</meme>
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