From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: [PATCH RFC 07/26] drivers/ata: Replace spin_unlock_wait() with lock/unlock pair Date: Thu, 29 Jun 2017 17:01:15 -0700 Message-ID: <1498780894-8253-7-git-send-email-paulmck@linux.vnet.ibm.com> References: <20170629235918.GA6445@linux.vnet.ibm.com> Return-path: In-Reply-To: <20170629235918.GA6445@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, oleg@redhat.com, akpm@linux-foundation.org, mingo@redhat.com, dave@stgolabs.net, manfred@colorfullife.com, tj@kernel.org, arnd@arndb.de, linux-arch@vger.kernel.org, will.deacon@arm.com, peterz@infradead.org, stern@rowland.harvard.edu, parri.andrea@gmail.com, torvalds@linux-foundation.org, "Paul E. McKenney" , linux-ide@vger.kernel.org List-Id: linux-arch.vger.kernel.org There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore eliminates the spin_unlock_wait() call and associated else-clause and hoists the then-clause's lock and unlock out of the "if" statement. This should be safe from a performance perspective because according to Tejun there should be few if any drivers that don't set their own error handler. Signed-off-by: Paul E. McKenney Acked-by: Tejun Heo Cc: Cc: Will Deacon Cc: Peter Zijlstra Cc: Alan Stern Cc: Andrea Parri Cc: Linus Torvalds --- drivers/ata/libata-eh.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index ef68232b5222..779f6f18c1f4 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -645,12 +645,11 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap, * completions are honored. A scmd is determined to have * timed out iff its associated qc is active and not failed. */ + spin_lock_irqsave(ap->lock, flags); if (ap->ops->error_handler) { struct scsi_cmnd *scmd, *tmp; int nr_timedout = 0; - spin_lock_irqsave(ap->lock, flags); - /* This must occur under the ap->lock as we don't want a polled recovery to race the real interrupt handler @@ -700,12 +699,11 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap, if (nr_timedout) __ata_port_freeze(ap); - spin_unlock_irqrestore(ap->lock, flags); /* initialize eh_tries */ ap->eh_tries = ATA_EH_MAX_TRIES; - } else - spin_unlock_wait(ap->lock); + } + spin_unlock_irqrestore(ap->lock, flags); } EXPORT_SYMBOL(ata_scsi_cmd_error_handler); -- 2.5.2 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40168 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751940AbdF3ABo (ORCPT ); Thu, 29 Jun 2017 20:01:44 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v5TNx5AE033741 for ; Thu, 29 Jun 2017 20:01:44 -0400 Received: from e12.ny.us.ibm.com (e12.ny.us.ibm.com [129.33.205.202]) by mx0b-001b2d01.pphosted.com with ESMTP id 2bd03bp8jj-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 29 Jun 2017 20:01:43 -0400 Received: from localhost by e12.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 29 Jun 2017 20:01:43 -0400 From: "Paul E. McKenney" Subject: [PATCH RFC 07/26] drivers/ata: Replace spin_unlock_wait() with lock/unlock pair Date: Thu, 29 Jun 2017 17:01:15 -0700 In-Reply-To: <20170629235918.GA6445@linux.vnet.ibm.com> References: <20170629235918.GA6445@linux.vnet.ibm.com> Message-ID: <1498780894-8253-7-git-send-email-paulmck@linux.vnet.ibm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, oleg@redhat.com, akpm@linux-foundation.org, mingo@redhat.com, dave@stgolabs.net, manfred@colorfullife.com, tj@kernel.org, arnd@arndb.de, linux-arch@vger.kernel.org, will.deacon@arm.com, peterz@infradead.org, stern@rowland.harvard.edu, parri.andrea@gmail.com, torvalds@linux-foundation.org, "Paul E. McKenney" , linux-ide@vger.kernel.org Message-ID: <20170630000115.G8Dg4A1S2hHEnWl22CGNvZC1RpSdOwcx3wamdNqkEek@z> There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore eliminates the spin_unlock_wait() call and associated else-clause and hoists the then-clause's lock and unlock out of the "if" statement. This should be safe from a performance perspective because according to Tejun there should be few if any drivers that don't set their own error handler. Signed-off-by: Paul E. McKenney Acked-by: Tejun Heo Cc: Cc: Will Deacon Cc: Peter Zijlstra Cc: Alan Stern Cc: Andrea Parri Cc: Linus Torvalds --- drivers/ata/libata-eh.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index ef68232b5222..779f6f18c1f4 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -645,12 +645,11 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap, * completions are honored. A scmd is determined to have * timed out iff its associated qc is active and not failed. */ + spin_lock_irqsave(ap->lock, flags); if (ap->ops->error_handler) { struct scsi_cmnd *scmd, *tmp; int nr_timedout = 0; - spin_lock_irqsave(ap->lock, flags); - /* This must occur under the ap->lock as we don't want a polled recovery to race the real interrupt handler @@ -700,12 +699,11 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap, if (nr_timedout) __ata_port_freeze(ap); - spin_unlock_irqrestore(ap->lock, flags); /* initialize eh_tries */ ap->eh_tries = ATA_EH_MAX_TRIES; - } else - spin_unlock_wait(ap->lock); + } + spin_unlock_irqrestore(ap->lock, flags); } EXPORT_SYMBOL(ata_scsi_cmd_error_handler); -- 2.5.2