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ide: orphan all buffered requests on DMA cancel 

If the guests canceles a DMA request we can prematurely
invoke all callbacks of buffered requests and flag all them
as orphaned. Ideally this avoids the need for draining all
requests. For CDROM devices this works in 100% of all cases.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1447345846-15624-5-git-send-email-pl@kamp.de
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
Peter Lieven 2015-11-17 15:06:29 -05:00 committed by John Snow
parent 1d8c11d631
commit 7cda62087c
1 changed files with 19 additions and 0 deletions
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19
hw/ide/pci.c
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@ -233,6 +233,22 @@ void bmdma_cmd_writeb(BMDMAState *bm, uint32_t val)
/* Ignore writes to SSBM if it keeps the old value */
if ((val & BM_CMD_START) != (bm->cmd & BM_CMD_START)) {
if (!(val & BM_CMD_START)) {
/* First invoke the callbacks of all buffered requests
* and flag those requests as orphaned. Ideally there
* are no unbuffered (Scatter Gather DMA Requests or
* write requests) pending and we can avoid to drain. */
IDEBufferedRequest *req;
IDEState *s = idebus_active_if(bm->bus);
QLIST_FOREACH(req, &s->buffered_requests, list) {
if (!req->orphaned) {
#ifdef DEBUG_IDE
printf("%s: invoking cb %p of buffered request %p with"
" -ECANCELED\n", __func__, req->original_cb, req);
#endif
req->original_cb(req->original_opaque, -ECANCELED);
}
req->orphaned = true;
}
/*
* We can't cancel Scatter Gather DMA in the middle of the
* operation or a partial (not full) DMA transfer would reach
@ -246,6 +262,9 @@ void bmdma_cmd_writeb(BMDMAState *bm, uint32_t val)
* aio operation with preadv/pwritev.
*/
if (bm->bus->dma->aiocb) {
#ifdef DEBUG_IDE
printf("%s: draining all remaining requests", __func__);
#endif
blk_drain_all();
assert(bm->bus->dma->aiocb == NULL);
}