80 lines
2.4 KiB
Diff
80 lines
2.4 KiB
Diff
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From fbde196c30e4797a51bda046ba514b187963d4ba Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 29 Jul 2019 23:34:16 +0200
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Subject: [PATCH] dma-helpers: ensure AIO callback is invoked after
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cancellation
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dma_aio_cancel unschedules the BH if there is one, which corresponds
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to the reschedule_dma case of dma_blk_cb. This can stall the DMA
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permanently, because dma_complete will never get invoked and therefore
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nobody will ever invoke the original AIO callback in dbs->common.cb.
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Fix this by invoking the callback (which is ensured to happen after
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a bdrv_aio_cancel_async, or done manually in the dbs->bh case), and
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add assertions to check that the DMA state machine is indeed waiting
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for dma_complete or reschedule_dma, but never both.
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Reported-by: John Snow <jsnow@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Message-id: 20190729213416.1972-1-pbonzini@redhat.com
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Signed-off-by: John Snow <jsnow@redhat.com>
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(cherry picked from commit 539343c0a47e19d5dd64d846d64d084d9793681f)
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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dma-helpers.c | 13 +++++++++----
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1 file changed, 9 insertions(+), 4 deletions(-)
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diff --git a/dma-helpers.c b/dma-helpers.c
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index 2d7e02d35e..d3871dc61e 100644
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--- a/dma-helpers.c
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+++ b/dma-helpers.c
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@@ -90,6 +90,7 @@ static void reschedule_dma(void *opaque)
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{
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DMAAIOCB *dbs = (DMAAIOCB *)opaque;
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+ assert(!dbs->acb && dbs->bh);
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qemu_bh_delete(dbs->bh);
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dbs->bh = NULL;
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dma_blk_cb(dbs, 0);
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@@ -111,15 +112,12 @@ static void dma_complete(DMAAIOCB *dbs, int ret)
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{
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trace_dma_complete(dbs, ret, dbs->common.cb);
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+ assert(!dbs->acb && !dbs->bh);
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dma_blk_unmap(dbs);
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if (dbs->common.cb) {
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dbs->common.cb(dbs->common.opaque, ret);
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}
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qemu_iovec_destroy(&dbs->iov);
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- if (dbs->bh) {
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- qemu_bh_delete(dbs->bh);
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- dbs->bh = NULL;
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- }
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qemu_aio_unref(dbs);
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}
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@@ -179,14 +177,21 @@ static void dma_aio_cancel(BlockAIOCB *acb)
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trace_dma_aio_cancel(dbs);
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+ assert(!(dbs->acb && dbs->bh));
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if (dbs->acb) {
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+ /* This will invoke dma_blk_cb. */
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blk_aio_cancel_async(dbs->acb);
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+ return;
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}
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+
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if (dbs->bh) {
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cpu_unregister_map_client(dbs->bh);
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qemu_bh_delete(dbs->bh);
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dbs->bh = NULL;
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}
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+ if (dbs->common.cb) {
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+ dbs->common.cb(dbs->common.opaque, -ECANCELED);
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+ }
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}
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static AioContext *dma_get_aio_context(BlockAIOCB *acb)
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--
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2.23.0
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