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authorPaolo Bonzini <pbonzini@redhat.com>2011-09-16 16:40:02 +0200
committerKevin Wolf <kwolf@redhat.com>2011-09-20 12:27:43 +0200
commitc3adb5b9168a57790b5074489b6f0275ac3cc8b5 (patch)
tree23c80fd5ded017fea0c0cde44673872498e80c83 /dma-helpers.c
parent10dc8aef419b4ce77670fb080ffe995bf9d7b0a1 (diff)
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dma-helpers: rewrite completion/cancellation
This fixes various problems with completion/cancellation: * if the io_func fails to get an AIOCB, the callback wasn't called * If DMA encounters a bounce buffer conflict, and the DMA operation is canceled before the bottom half fires, bad things happen. * memory is not unmapped after cancellation, again causing problems when doing DMA to I/O areas * cancellation could leak the iovec * the callback was missed if the I/O operation failed without returning an AIOCB and probably more that I've missed. The patch fixes them by sharing the cleanup code between completion and cancellation. The dma_bdrv_cb now returns a boolean completed/not completed flag, and the wrapper dma_continue takes care of tasks to do upon completion. Most of these are basically impossible in practice, but it is better to be tidy... Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'dma-helpers.c')
-rw-r--r--dma-helpers.c44
1 files changed, 31 insertions, 13 deletions
diff --git a/dma-helpers.c b/dma-helpers.c
index 717e384..86d2d0a 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -43,6 +43,7 @@ typedef struct {
QEMUSGList *sg;
uint64_t sector_num;
bool to_dev;
+ bool in_cancel;
int sg_cur_index;
target_phys_addr_t sg_cur_byte;
QEMUIOVector iov;
@@ -58,7 +59,7 @@ static void reschedule_dma(void *opaque)
qemu_bh_delete(dbs->bh);
dbs->bh = NULL;
- dma_bdrv_cb(opaque, 0);
+ dma_bdrv_cb(dbs, 0);
}
static void continue_after_map_failure(void *opaque)
@@ -78,6 +79,26 @@ static void dma_bdrv_unmap(DMAAIOCB *dbs)
dbs->iov.iov[i].iov_len, !dbs->to_dev,
dbs->iov.iov[i].iov_len);
}
+ qemu_iovec_reset(&dbs->iov);
+}
+
+static void dma_complete(DMAAIOCB *dbs, int ret)
+{
+ dma_bdrv_unmap(dbs);
+ if (dbs->common.cb) {
+ dbs->common.cb(dbs->common.opaque, ret);
+ }
+ qemu_iovec_destroy(&dbs->iov);
+ if (dbs->bh) {
+ qemu_bh_delete(dbs->bh);
+ dbs->bh = NULL;
+ }
+ if (!dbs->in_cancel) {
+ /* Requests may complete while dma_aio_cancel is in progress. In
+ * this case, the AIOCB should not be released because it is still
+ * referenced by dma_aio_cancel. */
+ qemu_aio_release(dbs);
+ }
}
static void dma_bdrv_cb(void *opaque, int ret)
@@ -89,12 +110,9 @@ static void dma_bdrv_cb(void *opaque, int ret)
dbs->acb = NULL;
dbs->sector_num += dbs->iov.size / 512;
dma_bdrv_unmap(dbs);
- qemu_iovec_reset(&dbs->iov);
if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
- dbs->common.cb(dbs->common.opaque, ret);
- qemu_iovec_destroy(&dbs->iov);
- qemu_aio_release(dbs);
+ dma_complete(dbs, ret);
return;
}
@@ -120,9 +138,7 @@ static void dma_bdrv_cb(void *opaque, int ret)
dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,
dbs->iov.size / 512, dma_bdrv_cb, dbs);
if (!dbs->acb) {
- dma_bdrv_unmap(dbs);
- qemu_iovec_destroy(&dbs->iov);
- return;
+ dma_complete(dbs, -EIO);
}
}
@@ -131,8 +147,14 @@ static void dma_aio_cancel(BlockDriverAIOCB *acb)
DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
if (dbs->acb) {
- bdrv_aio_cancel(dbs->acb);
+ BlockDriverAIOCB *acb = dbs->acb;
+ dbs->acb = NULL;
+ dbs->in_cancel = true;
+ bdrv_aio_cancel(acb);
+ dbs->in_cancel = false;
}
+ dbs->common.cb = NULL;
+ dma_complete(dbs, 0);
}
static AIOPool dma_aio_pool = {
@@ -158,10 +180,6 @@ BlockDriverAIOCB *dma_bdrv_io(
dbs->bh = NULL;
qemu_iovec_init(&dbs->iov, sg->nsg);
dma_bdrv_cb(dbs, 0);
- if (!dbs->acb) {
- qemu_aio_release(dbs);
- return NULL;
- }
return &dbs->common;
}