> -----Original Message----- > From: James Bottomley [mailto:jbottomley@xxxxxxxxxxxxx] > Sent: Friday, October 04, 2013 2:42 PM > To: KY Srinivasan > Cc: gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devel@xxxxxxxxxxxxxxxxxxxxxx; ohering@xxxxxxxx; hch@xxxxxxxxxxxxx; > eric@xxxxxxxxxxxxxxx; nab@xxxxxxxxxxxxxxx; linux-scsi@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 1/1] Drivers: scsi: Derive the FLUSH_TIMEOUT from the basic > I/O timeout > > 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 <eric@xxxxxxxxxxxxxxx> and > > Nicholas A. Bellinger <nab@xxxxxxxxxxxxxxx> for their help in resolving > > this issue. > > > > Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > > --- > > 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) > > /* Thanks James. Given that you have already made the changes you want done (in the Patch above), do you still want me to send you a fixed up patch? Regards, K. Y _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
