Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932113Ab2HFOgM (ORCPT ); Mon, 6 Aug 2012 10:36:12 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:12012 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756589Ab2HFOf1 (ORCPT ); Mon, 6 Aug 2012 10:35:27 -0400 X-IronPort-AV: E=Sophos;i="4.77,720,1336363200"; d="scan'208";a="204276921" From: Stefano Stabellini To: CC: , , , , , , , , , Stefano Stabellini Subject: [PATCH v2 04/23] xen/arm: sync_bitops Date: Mon, 6 Aug 2012 15:27:07 +0100 Message-ID: <1344263246-28036-4-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 Content-Length: 2237 Lines: 56 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 --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/