linux-kernel - [PATCH] ATM: fix warning

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Message-ID: <20070527104020.GA10665@havoc.gtf.org>
Date:	Sun, 27 May 2007 06:40:20 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Andrew Morton <akpm@...ux-foundation.org>, chas@....nrl.navy.mil
Cc:	LKML <linux-kernel@...r.kernel.org>, netdev@...r.kernel.org,
	linux-atm-general@...ts.sourceforge.net
Subject: [PATCH] ATM: fix warning


The compiler warning

drivers/atm/firestream.c: In function ‘top_off_fp’:
drivers/atm/firestream.c:1505: warning: cast to pointer from integer of different size

does indicate a bug, albeit a minor one.  Fixed, by using a 32-bit
temporary prior to the call to bus_to_virt().

The larger bug is still present:  the entire driver assumes that machine
pointers are 32-bit, as it stores pointers in 32-bit hardware registers.
This is obvious to anyone who knows the driver well, but for the casual
readers it is helpfully noted with FIXME.

Signed-off-by: Jeff Garzik <jeff@...zik.org>

diff --git a/drivers/atm/firestream.c b/drivers/atm/firestream.c
index 9c67df5..7f6d02c 100644
--- a/drivers/atm/firestream.c
+++ b/drivers/atm/firestream.c
@@ -1475,6 +1475,7 @@ static void top_off_fp (struct fs_dev *dev, struct freepool *fp,
 	struct FS_BPENTRY *qe, *ne;
 	struct sk_buff *skb;
 	int n = 0;
+	u32 qe_tmp;
 
 	fs_dprintk (FS_DEBUG_QUEUE, "Topping off queue at %x (%d-%d/%d)\n", 
 		    fp->offset, read_fs (dev, FP_CNT (fp->offset)), fp->n, 
@@ -1502,10 +1503,16 @@ static void top_off_fp (struct fs_dev *dev, struct freepool *fp,
 		ne->skb = skb;
 		ne->fp = fp;
 
-		qe = (struct FS_BPENTRY *) (read_fs (dev, FP_EA(fp->offset)));
-		fs_dprintk (FS_DEBUG_QUEUE, "link at %p\n", qe);
-		if (qe) {
-			qe = bus_to_virt ((long) qe);
+		/*
+		 * FIXME: following code encodes and decodes
+		 * machine pointers (could be 64-bit) into a
+		 * 32-bit register.
+		 */
+
+		qe_tmp = read_fs (dev, FP_EA(fp->offset));
+		fs_dprintk (FS_DEBUG_QUEUE, "link at %x\n", qe_tmp);
+		if (qe_tmp) {
+			qe = bus_to_virt ((long) qe_tmp);
 			qe->next = virt_to_bus(ne);
 			qe->flags &= ~FP_FLAGS_EPI;
 		} else
-
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