Re: "scsi: convert host_busy to atomic_t" series causes regressions for some hardware configurations

From: Sergio Callegari
Date: Sun Aug 30 2015 - 06:55:24 EST


Hi Christoph,

just checked.

Unfortunately, the patch below, applied on top of Linus' v3.17 (which I am using as a test kernel) *does not fix the issue*.

Best regards,

Sergio

On 25/08/2015 13:00, Christoph Hellwig wrote:
Hi Sergio,

can you give the patch below a try?

libata currently completes the SCSI command before freeing the internal
command structure, which could lead to various races that mess with
the ATA command state, which might cause issues like the one you see.

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 641a61a..92cc156 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1772,6 +1772,15 @@ nothing_to_do:
return 1;
}
+static void ata_qc_done(struct ata_queued_cmd *qc)
+{
+ struct scsi_cmnd *cmd = qc->scsicmd;
+ void (*done)(struct scsi_cmnd *) = qc->scsidone;
+
+ ata_qc_free(qc);
+ done(cmd);
+}
+
static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
@@ -1810,9 +1819,7 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
if (need_sense && !ap->ops->error_handler)
ata_dump_status(ap->print_id, &qc->result_tf);
- qc->scsidone(cmd);
-
- ata_qc_free(qc);
+ ata_qc_done(qc);
}
/**
@@ -2611,8 +2618,7 @@ static void atapi_sense_complete(struct ata_queued_cmd *qc)
ata_gen_passthru_sense(qc);
}
- qc->scsidone(qc->scsicmd);
- ata_qc_free(qc);
+ ata_qc_done(qc);
}
/* is it pointless to prefer PIO for "safety reasons"? */
@@ -2707,8 +2713,7 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
qc->dev->sdev->locked = 0;
qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;
- qc->scsidone(cmd);
- ata_qc_free(qc);
+ ata_qc_done(qc);
return;
}
@@ -2752,8 +2757,7 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
cmd->result = SAM_STAT_GOOD;
}
- qc->scsidone(cmd);
- ata_qc_free(qc);
+ ata_qc_done(qc);
}
/**
* atapi_xlat - Initialize PACKET taskfile

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