Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754843Ab3JDVms (ORCPT ); Fri, 4 Oct 2013 17:42:48 -0400 Received: from mx2.parallels.com ([199.115.105.18]:42319 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744Ab3JDVmq convert rfc822-to-8bit (ORCPT ); Fri, 4 Oct 2013 17:42:46 -0400 From: James Bottomley To: "K. Y. Srinivasan" CC: "gregkh@linuxfoundation.org" , "linux-kernel@vger.kernel.org" , "devel@linuxdriverproject.org" , "ohering@suse.com" , "hch@infradead.org" , "eric@purestorage.com" , "nab@linux-iscsi.org" , "linux-scsi@vger.kernel.org" Subject: Re: [PATCH 1/1] Drivers: scsi: Derive the FLUSH_TIMEOUT from the basic I/O timeout Thread-Topic: [PATCH 1/1] Drivers: scsi: Derive the FLUSH_TIMEOUT from the basic I/O timeout Thread-Index: AQHOwTQXtrhMaZFXTEu/YravllNS3JnliCkA Date: Fri, 4 Oct 2013 21:42:24 +0000 Message-ID: <1380922944.3868.8.camel@dabdike.int.hansenpartnership.com> References: <1380915516-28720-1-git-send-email-kys@microsoft.com> In-Reply-To: <1380915516-28720-1-git-send-email-kys@microsoft.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [24.17.213.192] Content-Type: text/plain; charset=US-ASCII Content-ID: <3571843CB1EE8A4D8AE3BD839A0DDA3A@sw.swsoft.com> Content-Transfer-Encoding: 7BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4184 Lines: 119 On Fri, 2013-10-04 at 12:38 -0700, K. Y. Srinivasan wrote: > Rather than having a separate constant for specifying the timeout on FLUSH > operations, use the basic I/O timeout value that is already configurable > on a per target basis to derive the FLUSH timeout. Looking at the current > definitions of these timeout values, the FLUSH operation is supposed to have > a value that is twice the normal timeout value. This patch preserves this > relationship while leveraging the flexibility of specifying the I/O timeout. > > I would like to thank Eric Seppanen and > Nicholas A. Bellinger for their help in resolving > this issue. > > Signed-off-by: K. Y. Srinivasan > --- > drivers/scsi/sd.c | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c > index e62d17d..8aff306 100644 > --- a/drivers/scsi/sd.c > +++ b/drivers/scsi/sd.c > @@ -829,7 +829,7 @@ static int sd_setup_write_same_cmnd(struct scsi_device *sdp, struct request *rq) > > static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq) > { > - rq->timeout = SD_FLUSH_TIMEOUT; > + rq->timeout *= 2; > rq->retries = SD_MAX_RETRIES; > rq->cmd[0] = SYNCHRONIZE_CACHE; > rq->cmd_len = 10; > @@ -1433,6 +1433,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp) > { > int retries, res; > struct scsi_device *sdp = sdkp->device; > + unsigned int timeout = sdp->request_queue->rq_timeout; The timeout is signed in the function prototype > struct scsi_sense_hdr sshdr; > > if (!scsi_device_online(sdp)) > @@ -1448,7 +1449,7 @@ static int sd_sync_cache(struct scsi_disk *sdkp) > * flush everything. > */ > res = scsi_execute_req_flags(sdp, cmd, DMA_NONE, NULL, 0, > - &sshdr, SD_FLUSH_TIMEOUT, > + &sshdr, timeout * 2, > SD_MAX_RETRIES, NULL, REQ_PM); > if (res == 0) > break; Not like this, please: you now leave us with a dangling #define whose name makes you think it should be related to flushing and a couple of curious magic constants. It's almost hand crafted to confuse people reading the code. Please do it like this instead: with a comment explaining what we're doing above the #define and a name that clearly relates to the actions. James --- diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index e62d17d..5c9496d 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -829,7 +829,7 @@ static int sd_setup_write_same_cmnd(struct scsi_device *sdp, struct request *rq) static int scsi_setup_flush_cmnd(struct scsi_device *sdp, struct request *rq) { - rq->timeout = SD_FLUSH_TIMEOUT; + rq->timeout *= SD_FLUSH_TIMEOUT_MULTIPLIER; rq->retries = SD_MAX_RETRIES; rq->cmd[0] = SYNCHRONIZE_CACHE; rq->cmd_len = 10; @@ -1433,6 +1433,8 @@ static int sd_sync_cache(struct scsi_disk *sdkp) { int retries, res; struct scsi_device *sdp = sdkp->device; + const int timeout = sdp->request_queue->rq_timeout + * SD_FLUSH_TIMEOUT_MULTIPLIER; struct scsi_sense_hdr sshdr; if (!scsi_device_online(sdp)) @@ -1448,8 +1450,8 @@ static int sd_sync_cache(struct scsi_disk *sdkp) * flush everything. */ res = scsi_execute_req_flags(sdp, cmd, DMA_NONE, NULL, 0, - &sshdr, SD_FLUSH_TIMEOUT, - SD_MAX_RETRIES, NULL, REQ_PM); + &sshdr, timeout, SD_MAX_RETRIES, + NULL, REQ_PM); if (res == 0) break; } diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h index 7a049de..7f7999c 100644 --- a/drivers/scsi/sd.h +++ b/drivers/scsi/sd.h @@ -13,7 +13,11 @@ */ #define SD_TIMEOUT (30 * HZ) #define SD_MOD_TIMEOUT (75 * HZ) -#define SD_FLUSH_TIMEOUT (60 * HZ) +/* + * Flush timeout is a multiplier over the standard device timeout which is + * user modifiable via sysfs but initially set to SD_TIMEOUT + */ +#define SD_FLUSH_TIMEOUT_MULTIPLIER 2 #define SD_WRITE_SAME_TIMEOUT (120 * HZ) /* -- 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/