Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751797Ab1EGFUZ (ORCPT ); Sat, 7 May 2011 01:20:25 -0400 Received: from smtp-out.google.com ([216.239.44.51]:6668 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751579Ab1EGFUX (ORCPT ); Sat, 7 May 2011 01:20:23 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=from:to:cc:subject:date:message-id:x-mailer; b=u/tGkqRmDrZBp+DhZa3Lh5XaitloS56iTqNCNLD4usEnZzUXMrMwYVFDa63inETbs l3g5Kr6mWboiIJnz+1pqg== From: Nat Gurumoorthy To: Jean Delvare , Guenter Roeck , Wim Van Sebroeck , lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org Cc: mikew@google.com, Nat Gurumoorthy Subject: [PATCH v9 0/2] Make all it87 drivers SMP safe Date: Fri, 6 May 2011 22:19:24 -0700 Message-Id: <1304745564-13003-1-git-send-email-natg@google.com> X-Mailer: git-send-email 1.7.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2589 Lines: 65 There are 3 different drivers that touch the it87 hardware registers. The 3 drivers have been written independently and access the it87 hardware registers assuming they are the only driver accessing it. This change attempts to serialize access to the hardware by using "request_muxed_region" macro defined by Alan Cox. Call to this macro will hold off the requestor if the resource is currently busy. The use of the above macro makes it possible to get rid of spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers. This also greatly simplifies the implementation of it87_wdt.c driver. 01 - Changes to it87 watchdog driver to use "request_muxed_region" drivers/watchdog/it8712f_wdt.c drivers/watchdog/it87_wdt.c 02 - Chages to hwmon it87 driver to use "request_muxed_region" drivers/hwmon/it87.c drivers/hwmon/it87.c | 31 +++++--- drivers/watchdog/it8712f_wdt.c | 62 +++++++++++---- drivers/watchdog/it87_wdt.c | 165 +++++++++++++++++++++++---------------- 3 files changed, 161 insertions(+), 97 deletions(-) Signed-off-by: Nat Gurumoorthy Patch History: v9: - More clean up in drivers/hwmon/it87.c. More fixes that of the type in V8 that got missed in drivers/watchdog/it8712f_wdt.c. v8: - Return the error actually returned by superio_enter and not -EBUSY. Notifier routines return NOTIFY_DONE even if underlying calls from notifier to routines that invoke superio_enter return with error. Make sure release routines returns do proper clean up even if calls to superio_enter fail. v7: - superio_enter return error if call to "request_muxed_region" fails. Rest of the changes deal with error returns from superio_enter. Changes to it87_wdt.c are untested. v6: - Pay attention to value returned by request_muxed_region. The first call to request_muxed_region will attempt 10 times to reserve the region before it gives up. This will typically get called from the driver init routines. If this succeeds then subsequent calls wait forever for the resource to be available. v5: - Remove unnecessary while from superio_enter. v4: - Remove extra braces in superio_enter routines. v3: - Totally abandon the spinlock based approach and use "request_muxed_region" to hold off requestors if the resource is busy. v2: - More verbose patch headers. Add In-Reply-To: field. -- 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/