From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:41309) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RNSQj-0001gS-P9 for qemu-devel@nongnu.org; Mon, 07 Nov 2011 11:52:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RNSQi-0004oQ-CH for qemu-devel@nongnu.org; Mon, 07 Nov 2011 11:52:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51285) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RNSQi-0004oB-4s for qemu-devel@nongnu.org; Mon, 07 Nov 2011 11:52:16 -0500 From: Kevin Wolf Date: Mon, 7 Nov 2011 17:55:10 +0100 Message-Id: <1320684918-6483-4-git-send-email-kwolf@redhat.com> In-Reply-To: <1320684918-6483-1-git-send-email-kwolf@redhat.com> References: <1320684918-6483-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 03/11] dma: Avoid reentrancy in DMA transfer handlers List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: anthony@codemonkey.ws Cc: kwolf@redhat.com, qemu-devel@nongnu.org With the conversion of the block layer to coroutines, bdrv_read/write have changed to run a nested event loop that calls qemu_bh_poll. Consequently a scheduled BH can be called while a DMA transfer handler runs and this means that DMA_run becomes reentrant. Devices haven't been designed to cope with that, so instead of running a nested transfer handler just wait for the next invocation of the BH from the main loop. This fixes some problems with the floppy device. Signed-off-by: Kevin Wolf --- hw/dma.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/hw/dma.c b/hw/dma.c index 8a7302a..0a9322d 100644 --- a/hw/dma.c +++ b/hw/dma.c @@ -358,6 +358,14 @@ static void DMA_run (void) struct dma_cont *d; int icont, ichan; int rearm = 0; + static int running = 0; + + if (running) { + rearm = 1; + goto out; + } else { + running = 1; + } d = dma_controllers; @@ -374,6 +382,8 @@ static void DMA_run (void) } } + running = 0; +out: if (rearm) qemu_bh_schedule_idle(dma_bh); } -- 1.7.6.4