Re: [PATCH] libsas: Don't issue commands to devices that have been hot-removed.
(digging through old email) Darrick J. Wong wrote: On Tue, Dec 04, 2007 at 05:48:33PM -0500, Jeff Garzik wrote: As an aside, issues like this really really imply a need to move libsas away from the old libata EH stuff (like brking did with ipr, in patches). Hm... does the new libata EH handle the case of "device was unplugged, don't bother trying to send any more commands"? Yes, most certainly :) We wouldn't have hotplug support without that... In general, I agree that sas-ata should adopt the new EH. Unfortunately, I believe the old way of sas-ata configuring ATA ports is somehow not compatible with the new EH stuff and causes a crash during the device probe with my patch to move sas-ata to the new EH. If I apply the patch that migrates sas-ata to use brking's latest ata-sas configuration mechanism (the one that creates real ata_hosts), I see (a) lots and lots of ATA hosts getting created (one per ATA port; possibly undesirable if you've a SAS topology with a lot of SATA disks) and (b) NCQ disks don't seem to work if you unplug the disk and plug it back in (unless NCQ is disabled entirely). Jeff, by any chance have you tried plugging SATA devices into your SAS controllers? Just tested mvsas here... James Bottomley wondered if it would be easier to have sas-ata call only into the parts of libata that convert SCSI commands to ATA taskfiles, though I'm unsure how many wormy cans that would open. Like Brian K noted, libata-EH is heavily involved in "anything not hotpath read/write", including but not limited to: PMP, hotplug, device probing, device revalidation, explicit sequencing of ATA commands during initialization (critical for getting many ATA devices working) You don't want to reinvent or duplicate all those ATA device initialization/revalidation quirks. Jeff - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] libsas: Don't issue commands to devices that have been hot-removed.
Darrick J. Wong wrote: > In general, I agree that sas-ata should adopt the new EH. > Unfortunately, I believe the old way of sas-ata configuring ATA ports is > somehow not compatible with the new EH stuff and causes a crash during > the device probe with my patch to move sas-ata to the new EH. If I > apply the patch that migrates sas-ata to use brking's latest ata-sas > configuration mechanism (the one that creates real ata_hosts), I see > (a) lots and lots of ATA hosts getting created (one per ATA port; > possibly undesirable if you've a SAS topology with a lot of SATA disks) The new libata EH ends up spending more time in the error handling thread than the old code did. One of the reasons having multiple ATA/SCSI hosts is a good thing is that is the granularity of error handling, so it prevents stalling all the other devices under that SAS HBA while we are hitting errors on an ATAPI SATA device, for example. Arguably, SATA users of libata already have one SCSI host per ATA port, so my SAS patches really just bring SAS in line with that design... -Brian -- Brian King Linux on Power Virtualization IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] libsas: Don't issue commands to devices that have been hot-removed.
Darrick J. Wong wrote: On Tue, Dec 04, 2007 at 05:48:33PM -0500, Jeff Garzik wrote: As an aside, issues like this really really imply a need to move libsas away from the old libata EH stuff (like brking did with ipr, in patches). Hm... does the new libata EH handle the case of "device was unplugged, don't bother trying to send any more commands"? In general, I agree that sas-ata should adopt the new EH. Unfortunately, I believe the old way of sas-ata configuring ATA ports is somehow not compatible with the new EH stuff and causes a crash during the device probe with my patch to move sas-ata to the new EH. If I apply the patch that migrates sas-ata to use brking's latest ata-sas configuration mechanism (the one that creates real ata_hosts), I see (a) lots and lots of ATA hosts getting created (one per ATA port; possibly undesirable if you've a SAS topology with a lot of SATA disks) and (b) NCQ disks don't seem to work if you unplug the disk and plug it back in (unless NCQ is disabled entirely). Jeff, by any chance have you tried plugging SATA devices into your SAS controllers? aic94xx yes, bcm and mv no. Will take a look though... James Bottomley wondered if it would be easier to have sas-ata call only into the parts of libata that convert SCSI commands to ATA taskfiles, though I'm unsure how many wormy cans that would open. You want more than that. You want to make sure libata is the place for knowledge about weird ATA devices, SATA quirks, ATA device error handling (to be distinguished from ATA /link/ error handling), and other areas. That stuff shouldn't be duplicated, and you /really/ do not want to re-learn all those lessons all over again ;-) Jeff - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] libsas: Don't issue commands to devices that have been hot-removed.
On Tue, Dec 04, 2007 at 05:48:33PM -0500, Jeff Garzik wrote: > As an aside, issues like this really really imply a need to move libsas > away from the old libata EH stuff (like brking did with ipr, in patches). Hm... does the new libata EH handle the case of "device was unplugged, don't bother trying to send any more commands"? In general, I agree that sas-ata should adopt the new EH. Unfortunately, I believe the old way of sas-ata configuring ATA ports is somehow not compatible with the new EH stuff and causes a crash during the device probe with my patch to move sas-ata to the new EH. If I apply the patch that migrates sas-ata to use brking's latest ata-sas configuration mechanism (the one that creates real ata_hosts), I see (a) lots and lots of ATA hosts getting created (one per ATA port; possibly undesirable if you've a SAS topology with a lot of SATA disks) and (b) NCQ disks don't seem to work if you unplug the disk and plug it back in (unless NCQ is disabled entirely). Jeff, by any chance have you tried plugging SATA devices into your SAS controllers? James Bottomley wondered if it would be easier to have sas-ata call only into the parts of libata that convert SCSI commands to ATA taskfiles, though I'm unsure how many wormy cans that would open. --D - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] libsas: Don't issue commands to devices that have been hot-removed.
Darrick J. Wong wrote: Hrm... does this patch help? You'll get a bunch of ATA/SAS disk errors printed to the screen if you yank the disk, but at least libsas won't get stuck waiting for the cache-flush commands to time out. --- sd will get hung up issuing commands to flush write cache if a SAS device is unplugged without warning. Change libsas to reject commands to domain devices that have already gone away. Signed-off-by: Darrick J. Wong <[EMAIL PROTECTED]> --- drivers/scsi/libsas/sas_ata.c |4 drivers/scsi/libsas/sas_expander.c |3 +++ drivers/scsi/libsas/sas_port.c |2 ++ drivers/scsi/libsas/sas_scsi_host.c |7 +++ include/scsi/libsas.h |1 + 5 files changed, 17 insertions(+), 0 deletions(-) Seems sane... diff --git a/drivers/scsi/libsas/sas_ata.c b/drivers/scsi/libsas/sas_ata.c index 0829b55..f5e5213 100644 --- a/drivers/scsi/libsas/sas_ata.c +++ b/drivers/scsi/libsas/sas_ata.c @@ -161,6 +161,10 @@ static unsigned int sas_ata_qc_issue(struct ata_queued_cmd *qc) unsigned int num = 0; unsigned int xfer = 0; + /* If the device fell off, no sense in issuing commands */ + if (dev->gone) + return AC_ERR_SYSTEM; + task = sas_alloc_task(GFP_ATOMIC); if (!task) return AC_ERR_SYSTEM; As an aside, issues like this really really imply a need to move libsas away from the old libata EH stuff (like brking did with ipr, in patches). Jeff - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
