From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932165Ab0CaANg (ORCPT ); Tue, 30 Mar 2010 20:13:36 -0400 Received: from kroah.org ([198.145.64.141]:51903 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756802Ab0C3XRs (ORCPT ); Tue, 30 Mar 2010 19:17:48 -0400 X-Mailbox-Line: From linux@linux.site Tue Mar 30 15:56:18 2010 Message-Id: <20100330225618.196697028@linux.site> User-Agent: quilt/0.47-14.9 Date: Tue, 30 Mar 2010 15:55:10 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, "David S. Miller" , Greg Kroah-Hartman Subject: [032/116] [PATCH] sparc64: Make prom entry spinlock NMI safe. In-Reply-To: <20100330230600.GA28802@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: David S. Miller [ Upstream commit 8a4fd1e4922413cfdfa6c51a59efb720d904a5eb ] If we do something like try to print to the OF console from an NMI while we're already in OpenFirmware, we'll deadlock on the spinlock. Use a raw spinlock and disable NMIs when we take it. Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- arch/sparc/prom/p1275.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/arch/sparc/prom/p1275.c +++ b/arch/sparc/prom/p1275.c @@ -32,8 +32,7 @@ extern void prom_cif_interface(void); extern void prom_cif_callback(void); /* - * This provides SMP safety on the p1275buf. prom_callback() drops this lock - * to allow recursuve acquisition. + * This provides SMP safety on the p1275buf. */ DEFINE_SPINLOCK(prom_entry_lock); @@ -47,7 +46,9 @@ long p1275_cmd(const char *service, long p = p1275buf.prom_buffer; - spin_lock_irqsave(&prom_entry_lock, flags); + raw_local_save_flags(flags); + raw_local_irq_restore(PIL_NMI); + spin_lock(&prom_entry_lock); p1275buf.prom_args[0] = (unsigned long)p; /* service */ strcpy (p, service); @@ -139,7 +140,8 @@ long p1275_cmd(const char *service, long va_end(list); x = p1275buf.prom_args [nargs + 3]; - spin_unlock_irqrestore(&prom_entry_lock, flags); + spin_unlock(&prom_entry_lock); + raw_local_irq_restore(flags); return x; }