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[PATCH] libata: clear ap->active_tag atomically w.r.t. command completion

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ap->active_tag was cleared in ata_qc_free().  This left ap->active_tag
dangling after ata_qc_complete().  Spurious interrupts inbetween could
incorrectly access the qc.  Clear active_tag in ata_qc_complete().
This change is necessary for later EH changes.

Signed-off-by: Tejun Heo <htejun@gmail.com>
This commit is contained in:
Tejun Heo 2006-05-15 20:57:32 +09:00
parent f8c2c4202d
commit 7401abf2f4
1 changed files with 3 additions and 2 deletions
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5
drivers/scsi/libata-core.c
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@ -4083,8 +4083,6 @@ void ata_qc_free(struct ata_queued_cmd *qc)
qc->flags = 0;
tag = qc->tag;
if (likely(ata_tag_valid(tag))) {
if (tag == ap->active_tag)
ap->active_tag = ATA_TAG_POISON;
qc->tag = ATA_TAG_POISON;
clear_bit(tag, &ap->qactive);
}
@ -4098,6 +4096,9 @@ void __ata_qc_complete(struct ata_queued_cmd *qc)
if (likely(qc->flags & ATA_QCFLAG_DMAMAP))
ata_sg_clean(qc);
/* command should be marked inactive atomically with qc completion */
qc->ap->active_tag = ATA_TAG_POISON;
/* atapi: mark qc as inactive to prevent the interrupt handler
* from completing the command twice later, before the error handler
* is called. (when rc != 0 and atapi request sense is needed)