linux-kernel - [115/151] b43legacy: avoid PPC fault during resume

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Message-Id: <20091217035657.891238507@mini.kroah.org>
Date:	Wed, 16 Dec 2009 19:56:52 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Larry Finger <Larry.Finger@...inger.net>,
	"John W. Linville" <linville@...driver.com>
Subject: [115/151] b43legacy: avoid PPC fault during resume

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Larry Finger <Larry.Finger@...inger.net>

commit 316a4d966cae3c2dec83ebb1ee1a3515f97b30ff upstream.

For PPC architecture with PHY Revision < 3, a read of the register
B43_MMIO_HWENABLED_LO will cause a CPU fault unless b43legacy_status()
returns a value of 2 (B43legacy_STAT_STARTED); however, one finds that
the driver is unable to associate after resuming from hibernation unless
this routine returns 1. To satisfy both conditions, the routine is rewritten
to return TRUE whenever b43legacy_status() returns a value < 2.

This patch fixes the second problem listed in the postings for Red Hat
Bugzilla #538523.

Signed-off-by: Larry Finger <Larry.Finger@...inger.net>
Signed-off-by: John W. Linville <linville@...driver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/net/wireless/b43legacy/rfkill.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/net/wireless/b43legacy/rfkill.c
+++ b/drivers/net/wireless/b43legacy/rfkill.c
@@ -34,6 +34,13 @@ bool b43legacy_is_hw_radio_enabled(struc
 		      & B43legacy_MMIO_RADIO_HWENABLED_HI_MASK))
 			return 1;
 	} else {
+		/* To prevent CPU fault on PPC, do not read a register
+		 * unless the interface is started; however, on resume
+		 * for hibernation, this routine is entered early. When
+		 * that happens, unconditionally return TRUE.
+		 */
+		if (b43legacy_status(dev) < B43legacy_STAT_STARTED)
+			return 1;
 		if (b43legacy_read16(dev, B43legacy_MMIO_RADIO_HWENABLED_LO)
 		    & B43legacy_MMIO_RADIO_HWENABLED_LO_MASK)
 			return 1;

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