libata: only call ->done once all per-tag ressources are released
When calling ->done before releasing resources we could run into a
race where the SCSI midlayer sends another command and races with
the resources beeing manipulated. For libata this can't currently
happen as synchronization happens at a higher level, but I'd still
like to fix it to future proof libata and to avoid copy & paste
into SCSI drivers where this pattern has led to reproducible crashes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index ebcba85..560cede 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1757,6 +1757,15 @@
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;
@@ -1784,9 +1793,7 @@
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);
}
/**
@@ -2588,8 +2595,7 @@
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"? */
@@ -2684,8 +2690,7 @@
qc->dev->sdev->locked = 0;
qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;
- qc->scsidone(cmd);
- ata_qc_free(qc);
+ ata_qc_done(qc);
return;
}
@@ -2729,8 +2734,7 @@
cmd->result = SAM_STAT_GOOD;
}
- qc->scsidone(cmd);
- ata_qc_free(qc);
+ ata_qc_done(qc);
}
/**
* atapi_xlat - Initialize PACKET taskfile