[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when drai
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS |
Date: |
Thu, 9 Nov 2017 15:02:23 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 |
On 11/09/2017 02:43 PM, Max Reitz wrote:
> Draining a BDS may lead to graph modifications, which in turn may result
> in it and other BDS being stripped of their current references. If
> bdrv_drain_all_begin() and bdrv_drain_all_end() do not keep strong
> references themselves, the BDS they are trying to drain (or undrain) may
> disappear right under their feet -- or, more specifically, under the
> feet of BDRV_POLL_WHILE() in bdrv_drain_recurse().
>
> This fixes an occasional hang of iotest 194.
>
> Signed-off-by: Max Reitz <address@hidden>
> ---
> block/io.c | 47 ++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 44 insertions(+), 3 deletions(-)
> +
> + /* Keep a strong reference to all root BDS and copy them into
> + * an own list because draining them may lead to graph
'an own' sounds awkward; maybe 'copy them into a local list'
> + * modifications. */
> + bdrv_ref(bs);
> + bs_list = g_slist_prepend(bs_list, bs);
> }
> void bdrv_drain_all_end(void)
> {
> BlockDriverState *bs;
> BdrvNextIterator it;
> + GSList *bs_list = NULL, *bs_list_entry;
> +
> + /* Must be called from the main loop */
> + assert(qemu_get_current_aio_context() == qemu_get_aio_context());
>
> + /* Keep a strong reference to all root BDS and copy them into an
> + * own list because draining them may lead to graph modifications.
And again.
With that tweak,
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
signature.asc
Description: OpenPGP digital signature
- [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Max Reitz, 2017/11/09
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS,
Eric Blake <=
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Fam Zheng, 2017/11/09
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Kevin Wolf, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Fam Zheng, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Max Reitz, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Fam Zheng, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Kevin Wolf, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Max Reitz, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Kevin Wolf, 2017/11/10
- Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Max Reitz, 2017/11/10
Re: [Qemu-devel] [PATCH for-2.11] block: Keep strong reference when draining all BDS, Stefan Hajnoczi, 2017/11/10