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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>
This commit is contained in:
Christoph Hellwig 2015-10-08 10:25:41 +02:00 committed by Tejun Heo
parent 25c7ce7f7b
commit 2aa8f5d63d
1 changed files with 13 additions and 9 deletions
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22
drivers/ata/libata-scsi.c
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@ -1757,6 +1757,15 @@ static unsigned int ata_scsi_rw_xlat(struct ata_queued_cmd *qc)
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 @@ 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);
}
/**
@ -2588,8 +2595,7 @@ 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"? */
@ -2684,8 +2690,7 @@ 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;
}
@ -2729,8 +2734,7 @@ 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