From c3adb5b9168a57790b5074489b6f0275ac3cc8b5 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 16 Sep 2011 16:40:02 +0200 Subject: 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 Signed-off-by: Kevin Wolf --- dma-helpers.c | 44 +++++++++++++++++++++++++++++++------------- 1 file changed, 31 insertions(+), 13 deletions(-) (limited to 'dma-helpers.c') diff --git a/dma-helpers.c b/dma-helpers.c index 717e384104..86d2d0a997 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; } -- cgit v1.2.1