53 lines
1.3 KiB
Diff
53 lines
1.3 KiB
Diff
From 86f1e4e2f57af82aae0944ed704ab91dc36fc9b7 Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Fri, 28 Oct 2011 05:28:13 -0400
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Subject: [PATCH 2/2] dma: Avoid reentrancy in DMA transfer handlers
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With the conversion of the block layer to coroutines, bdrv_read/write
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have changed to run a nested event loop that calls qemu_bh_poll.
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Consequently a scheduled BH can be called while a DMA transfer handler
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runs and this means that DMA_run becomes reentrant.
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Devices haven't been designed to cope with that, so instead of running a
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nested transfer handler just wait for the next invocation of the BH from the
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main loop.
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This fixes some problems with the floppy device.
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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hw/dma.c | 10 ++++++++++
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1 files changed, 10 insertions(+), 0 deletions(-)
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diff --git a/hw/dma.c b/hw/dma.c
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index 8a7302a..0a9322d 100644
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--- a/hw/dma.c
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+++ b/hw/dma.c
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@@ -358,6 +358,14 @@ static void DMA_run (void)
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struct dma_cont *d;
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int icont, ichan;
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int rearm = 0;
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+ static int running = 0;
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+
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+ if (running) {
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+ rearm = 1;
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+ goto out;
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+ } else {
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+ running = 1;
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+ }
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d = dma_controllers;
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@@ -374,6 +382,8 @@ static void DMA_run (void)
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}
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}
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+ running = 0;
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+out:
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if (rearm)
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qemu_bh_schedule_idle(dma_bh);
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}
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--
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1.7.7.5
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