From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756958Ab2IQRkI (ORCPT ); Mon, 17 Sep 2012 13:40:08 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:56100 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756383Ab2IQRj7 (ORCPT ); Mon, 17 Sep 2012 13:39:59 -0400 X-IronPort-AV: E=Sophos;i="4.80,437,1344211200"; d="scan'208";a="208319290" From: Stefano Stabellini To: CC: , , , , , , , , , Stefano Stabellini Subject: [PATCH v5 04/17] xen/arm: sync_bitops Date: Mon, 17 Sep 2012 18:38:50 +0100 Message-ID: <1347903543-2135-4-git-send-email-stefano.stabellini@eu.citrix.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sync_bitops functions are equivalent to the SMP implementation of the original functions, independently from CONFIG_SMP being defined. We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But under Xen you might be communicating with a completely external entity who might be on another CPU (e.g. two uniprocessor guests communicating via event channels and grant tables). So we need a variant of the bit ops which are SMP safe even on a UP kernel. Signed-off-by: Stefano Stabellini Acked-by: Konrad Rzeszutek Wilk --- arch/arm/include/asm/sync_bitops.h | 27 +++++++++++++++++++++++++++ 1 files changed, 27 insertions(+), 0 deletions(-) create mode 100644 arch/arm/include/asm/sync_bitops.h diff --git a/arch/arm/include/asm/sync_bitops.h b/arch/arm/include/asm/sync_bitops.h new file mode 100644 index 0000000..63479ee --- /dev/null +++ b/arch/arm/include/asm/sync_bitops.h @@ -0,0 +1,27 @@ +#ifndef __ASM_SYNC_BITOPS_H__ +#define __ASM_SYNC_BITOPS_H__ + +#include +#include + +/* sync_bitops functions are equivalent to the SMP implementation of the + * original functions, independently from CONFIG_SMP being defined. + * + * We need them because _set_bit etc are not SMP safe if !CONFIG_SMP. But + * under Xen you might be communicating with a completely external entity + * who might be on another CPU (e.g. two uniprocessor guests communicating + * via event channels and grant tables). So we need a variant of the bit + * ops which are SMP safe even on a UP kernel. + */ + +#define sync_set_bit(nr, p) _set_bit(nr, p) +#define sync_clear_bit(nr, p) _clear_bit(nr, p) +#define sync_change_bit(nr, p) _change_bit(nr, p) +#define sync_test_and_set_bit(nr, p) _test_and_set_bit(nr, p) +#define sync_test_and_clear_bit(nr, p) _test_and_clear_bit(nr, p) +#define sync_test_and_change_bit(nr, p) _test_and_change_bit(nr, p) +#define sync_test_bit(nr, addr) test_bit(nr, addr) +#define sync_cmpxchg cmpxchg + + +#endif -- 1.7.2.5