[PATCH] libata: Prevent the interrupt handler from completing a command twice
Problem:
During the libata CD-ROM stress test, sometimes the "BUG: timeout
without command" error is seen.
Root cause:
Unexpected interrupt occurs after the ata_qc_complete() is called,
but before the SCSI error handler. The interrupt handler is invoked
before the SCSI error handler, and it clears the command by calling
ata_qc_complete() again. Later when the SCSI error handler is run,
the ata_queued_cmd is already gone, causing the "BUG: timeout without
command" error.
Changes:
- Use the ATA_QCFLAG_ACTIVE flag to prevent the interrupt handler
from completing the command twice, before the scsi_error_handler.
Signed-off-by: Albert Lee <albertcc@tw.ibm.com>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 0b5d3a5..f70935c 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -2539,7 +2539,7 @@
ata_sg_init_one(qc, cmd->sense_buffer, sizeof(cmd->sense_buffer));
qc->dma_dir = DMA_FROM_DEVICE;
- memset(&qc->cdb, 0, sizeof(ap->cdb_len));
+ memset(&qc->cdb, 0, ap->cdb_len);
qc->cdb[0] = REQUEST_SENSE;
qc->cdb[4] = SCSI_SENSE_BUFFERSIZE;
@@ -2811,6 +2811,7 @@
/* call completion callback */
rc = qc->complete_fn(qc, drv_stat);
+ qc->flags &= ~ATA_QCFLAG_ACTIVE;
/* if callback indicates not to complete command (non-zero),
* return immediately
@@ -3229,7 +3230,8 @@
struct ata_queued_cmd *qc;
qc = ata_qc_from_tag(ap, ap->active_tag);
- if (qc && (!(qc->tf.ctl & ATA_NIEN)))
+ if (qc && (!(qc->tf.ctl & ATA_NIEN)) &&
+ (qc->flags & ATA_QCFLAG_ACTIVE))
handled |= ata_host_intr(ap, qc);
}
}