| Submitter | Nishanth Aravamudan |
|---|---|
| Date | June 15, 2011, 7:17 p.m. |
| Message ID | <20110615191747.GA6324@us.ibm.com> |
| Download | mbox | patch |
| Permalink | /patch/100567/ |
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
Comments
On 06/15/2011 02:17 PM, Nishanth Aravamudan wrote: > From what I can tell, the only place that explicitly clears the FROZEN > flag is the error-handling code via ata_eh_thaw_port(). > > So I thought either we're not invoking the error-handler at probe time > correctly to kick the port or perhaps the SAS code is not clearing the > flag? > > I tried the following patch: > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > index d51f979..abd0e0b 100644 > --- a/drivers/ata/libata-scsi.c > +++ b/drivers/ata/libata-scsi.c > @@ -3797,6 +3797,7 @@ EXPORT_SYMBOL_GPL(ata_sas_port_alloc); > */ > int ata_sas_port_start(struct ata_port *ap) > { > + ap->pflags &= ~ATA_PFLAG_FROZEN; > return 0; > } > EXPORT_SYMBOL_GPL(ata_sas_port_start); > > and the CD-ROM drive works, but I have no idea if it's the right thing > to do. I chose this particular change, FWIW, because we call > ata_sas_port_start before we probe in ata_sas_port_init and it seems > like we need to mark the port as not frozen before we init it? Perhaps > that should really be a call to a thaw function, not sure. Let's just > say the ATA/SAS/SCSI interactions are a bit hard to follow at first :) That looks like the right thing to do. For ipr's usage of libata, we don't have the concept of a port frozen state, so this flag should really never get set. The alternate way to fix this would be to only set ATA_PFLAG_FROZEN in ata_port_alloc if ap->ops->error_handler is not NULL. Thanks, Brian
On 15.06.2011 [15:02:18 -0500], Brian King wrote: > On 06/15/2011 02:17 PM, Nishanth Aravamudan wrote: > > From what I can tell, the only place that explicitly clears the FROZEN > > flag is the error-handling code via ata_eh_thaw_port(). > > > > So I thought either we're not invoking the error-handler at probe time > > correctly to kick the port or perhaps the SAS code is not clearing the > > flag? > > > > I tried the following patch: > > > > diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c > > index d51f979..abd0e0b 100644 > > --- a/drivers/ata/libata-scsi.c > > +++ b/drivers/ata/libata-scsi.c > > @@ -3797,6 +3797,7 @@ EXPORT_SYMBOL_GPL(ata_sas_port_alloc); > > */ > > int ata_sas_port_start(struct ata_port *ap) > > { > > + ap->pflags &= ~ATA_PFLAG_FROZEN; > > return 0; > > } > > EXPORT_SYMBOL_GPL(ata_sas_port_start); > > > > and the CD-ROM drive works, but I have no idea if it's the right thing > > to do. I chose this particular change, FWIW, because we call > > ata_sas_port_start before we probe in ata_sas_port_init and it seems > > like we need to mark the port as not frozen before we init it? Perhaps > > that should really be a call to a thaw function, not sure. Let's just > > say the ATA/SAS/SCSI interactions are a bit hard to follow at first :) > > That looks like the right thing to do. For ipr's usage of > libata, we don't have the concept of a port frozen state, so this flag > should really never get set. The alternate way to fix this would be to > only set ATA_PFLAG_FROZEN in ata_port_alloc if ap->ops->error_handler > is not NULL. It seemed like ipr is as you say, but I wasn't sure if it was appropriate to make the change above in the common libata-scis code or not. I don't want to break some other device on accident. Also, I tried your suggestion, but I don't think that can happen in ata_port_alloc? ata_port_alloc is allocated ap itself, and it seems like ap->ops typically gets set only after ata_port_alloc returns? Thanks, Nish
On Wed, Jun 15, 2011 at 04:34:17PM -0700, Nishanth Aravamudan wrote: > > That looks like the right thing to do. For ipr's usage of > > libata, we don't have the concept of a port frozen state, so this flag > > should really never get set. The alternate way to fix this would be to > > only set ATA_PFLAG_FROZEN in ata_port_alloc if ap->ops->error_handler > > is not NULL. > > It seemed like ipr is as you say, but I wasn't sure if it was > appropriate to make the change above in the common libata-scis code or > not. I don't want to break some other device on accident. > > Also, I tried your suggestion, but I don't think that can happen in > ata_port_alloc? ata_port_alloc is allocated ap itself, and it seems like > ap->ops typically gets set only after ata_port_alloc returns? Maybe we can test error_handler in ata_sas_port_start()? Thanks.
On 06/16/2011 02:51 AM, Tejun Heo wrote: > On Wed, Jun 15, 2011 at 04:34:17PM -0700, Nishanth Aravamudan wrote: >>> That looks like the right thing to do. For ipr's usage of >>> libata, we don't have the concept of a port frozen state, so this flag >>> should really never get set. The alternate way to fix this would be to >>> only set ATA_PFLAG_FROZEN in ata_port_alloc if ap->ops->error_handler >>> is not NULL. >> >> It seemed like ipr is as you say, but I wasn't sure if it was >> appropriate to make the change above in the common libata-scis code or >> not. I don't want to break some other device on accident. >> >> Also, I tried your suggestion, but I don't think that can happen in >> ata_port_alloc? ata_port_alloc is allocated ap itself, and it seems like >> ap->ops typically gets set only after ata_port_alloc returns? > > Maybe we can test error_handler in ata_sas_port_start()? Good point. Since libsas is converted to the new eh now, we would need to have this test. Thanks, Brian
Patch
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index d51f979..abd0e0b 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -3797,6 +3797,7 @@ EXPORT_SYMBOL_GPL(ata_sas_port_alloc); */ int ata_sas_port_start(struct ata_port *ap) { + ap->pflags &= ~ATA_PFLAG_FROZEN; return 0; } EXPORT_SYMBOL_GPL(ata_sas_port_start);
Hi Jeff, It appears that commit 7b3a24c57d2eeda8dba9c205342b12689c4679f9 broke CD-ROMs on the IPR SATA bus on powerpc machines: ata_port_alloc: ENTER ata_port_probe: ata1: bus probe begin ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: limiting speed to UDMA7:PIO5 ata1.00: ata_dev_read_id: ENTER ata1.00: failed to IDENTIFY (I/O error, err_mask=0x40) ata1.00: disabled ata_port_probe: ata1: bus probe end scsi_alloc_sdev: Allocation failure during SCSI scanning, some SCSI devices might not be configured The commit in question is tagged as AHCI, but does touch the libata core. I'm not well-versed with this code, but here's what I think I know :) From __scsi_add_device, we first allocate the target: scsi_alloc_target -> shost->hostt->target_alloc -> ipr_target_alloc -> ata_port_alloc -> sets FROZEN We error out when we allocate the sdev: scsi_alloc_sdev -> shost->hostt->slave_alloc -> ipr_slave_alloc -> ipr_ata_slave_alloc -> ata_sas_port_init -> ata_port_probe From what I can tell, the only place that explicitly clears the FROZEN flag is the error-handling code via ata_eh_thaw_port(). So I thought either we're not invoking the error-handler at probe time correctly to kick the port or perhaps the SAS code is not clearing the flag? I tried the following patch: and the CD-ROM drive works, but I have no idea if it's the right thing to do. I chose this particular change, FWIW, because we call ata_sas_port_start before we probe in ata_sas_port_init and it seems like we need to mark the port as not frozen before we init it? Perhaps that should really be a call to a thaw function, not sure. Let's just say the ATA/SAS/SCSI interactions are a bit hard to follow at first :) Any insight you can provide would be great! Thanks, Nish