From: "Michael S. Tsirkin" <mst@redhat.com>
To: Dima Stepanov <dimastep@yandex-team.ru>
Cc: fam@euphon.net, kwolf@redhat.com, yc-core@yandex-team.ru,
qemu-block@nongnu.org, Jason Wang <jasowang@redhat.com>,
qemu-devel@nongnu.org, dgilbert@redhat.com,
arei.gonglei@huawei.com, fengli@smartx.com, stefanha@redhat.com,
marcandre.lureau@redhat.com, pbonzini@redhat.com,
raphael.norwitz@nutanix.com, mreitz@redhat.com
Subject: Re: [PATCH v2 5/5] vhost: add device started check in migration set log
Date: Tue, 19 May 2020 05:59:07 -0400 [thread overview]
Message-ID: <20200517101303-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20200515165449.GA1627@dimastep-nix>
On Fri, May 15, 2020 at 07:54:57PM +0300, Dima Stepanov wrote:
> On Thu, May 14, 2020 at 03:34:24PM +0800, Jason Wang wrote:
> >
> > On 2020/5/13 下午5:47, Dima Stepanov wrote:
> > >>> case CHR_EVENT_CLOSED:
> > >>> /* a close event may happen during a read/write, but vhost
> > >>> * code assumes the vhost_dev remains setup, so delay the
> > >>> * stop & clear to idle.
> > >>> * FIXME: better handle failure in vhost code, remove bh
> > >>> */
> > >>> if (s->watch) {
> > >>> AioContext *ctx = qemu_get_current_aio_context();
> > >>>
> > >>> g_source_remove(s->watch);
> > >>> s->watch = 0;
> > >>> qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL,
> > >>> NULL, NULL, false);
> > >>>
> > >>> aio_bh_schedule_oneshot(ctx, chr_closed_bh, opaque);
> > >>> }
> > >>> break;
> > >>>
> > >>>I think it's time we dropped the FIXME and moved the handling to common
> > >>>code. Jason? Marc-André?
> > >>I agree. Just to confirm, do you prefer bh or doing changes like what is
> > >>done in this series? It looks to me bh can have more easier codes.
> > >Could it be a good idea just to make disconnect in the char device but
> > >postphone clean up in the vhost-user-blk (or any other vhost-user
> > >device) itself? So we are moving the postphone logic and decision from
> > >the char device to vhost-user device. One of the idea i have is as
> > >follows:
> > > - Put ourself in the INITIALIZATION state
> > > - Start these vhost-user "handshake" commands
> > > - If we got a disconnect error, perform disconnect, but don't clean up
> > > device (it will be clean up on the roll back). I can be done by
> > > checking the state in vhost_user_..._disconnect routine or smth like it
> >
> >
> > Any issue you saw just using the aio bh as Michael posted above.
> >
> > Then we don't need to deal with the silent vhost_dev_stop() and we will have
> > codes that is much more easier to understand.
> I've implemented this solution inside
> hw/block/vhost-user-blk.c:vhost_user_blk_event() in the similar way by
> using the s->connected field. Looks good and more correct fix ). I have
> two questions here before i'll rework the fixes:
> 1. Is it okay to make the similar fix inside vhost_user_blk_event() or
> we are looking for more generic vhost-user solution? What do you think?
Either works I think.
> 2. For migration we require an additional information that for the
> vhost-user device it isn't an error, because i'm trigerring the
> following assert error:
> Core was generated by `x86_64-softmmu/qemu-system-x86_64 -nodefaults -no-user-config -M q35,sata=false'.
> Program terminated with signal SIGABRT, Aborted.
> #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6
> [Current thread is 1 (Thread 0x7fb486ef5700 (LWP 527734))]
>
> (gdb) bt
> #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6
> #1 0x00007fb56e72b02a in abort () from /lib/x86_64-linux-gnu/libc.so.6
> #2 0x00005648ea376ee6 in vhost_log_global_start
> (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857
> #3 0x00005648ea2dde7e in memory_global_dirty_log_start ()
> at ./memory.c:2611
> #4 0x00005648ea2e68e7 in ram_init_bitmaps (rs=0x7fb4740008c0)
> at ./migration/ram.c:2305
> #5 0x00005648ea2e698b in ram_init_all (rsp=0x5648eb1f0f20 <ram_state>)
> at ./migration/ram.c:2323
> #6 0x00005648ea2e6cc5 in ram_save_setup (f=0x5648ec609e00,
> opaque=0x5648eb1f0f20 <ram_state>)
> at ./migration/ram.c:2436
> #7 0x00005648ea67b7d3 in qemu_savevm_state_setup (f=0x5648ec609e00) at
> migration/savevm.c:1176
> #8 0x00005648ea674511 in migration_thread (opaque=0x5648ec031ff0) at
> migration/migration.c:3416
> #9 0x00005648ea85d65d in qemu_thread_start (args=0x5648ec6057f0) at
> util/qemu-thread-posix.c:519
> #10 0x00007fb56eac56ba in start_thread () from
> /lib/x86_64-linux-gnu/libpthread.so.0
> #11 0x00007fb56e7fb41d in clone () from /lib/x86_64-linux-gnu/libc.so.6
> (gdb) frame 2
> #2 0x00005648ea376ee6 in vhost_log_global_start
> (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857
> 857 abort();
> (gdb) list
> 852 {
> 853 int r;
> 854
> 855 r = vhost_migration_log(listener, true);
> 856 if (r < 0) {
> 857 abort();
> 858 }
> 859 }
> 860
> 861 static void vhost_log_global_stop(MemoryListener *listener)
> Since bh postphone the clean up, we can't use the ->started field.
> Do we have any mechanism to get the device type/state in the common
> vhost_migration_log() routine? So for example for the vhost-user/disconnect
> device we will be able to return 0. Or should we implement it and introduce
> it in this patch set?
>
> Thanks, Dima.
>
> >
> > Thank
> >
> >
> > > - vhost-user command returns error back to the _start() routine
> > > - Rollback in one place in the start() routine, by calling this
> > > postphoned clean up for the disconnect
> > >
> >
next prev parent reply other threads:[~2020-05-19 10:00 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 13:36 [PATCH v2 0/5] vhost-user reconnect issues during vhost initialization Dima Stepanov
2020-04-30 13:36 ` [PATCH v2 1/5] char-socket: return -1 in case of disconnect during tcp_chr_write Dima Stepanov
2020-05-06 8:54 ` Li Feng
2020-05-06 9:46 ` Marc-André Lureau
2020-04-30 13:36 ` [PATCH v2 2/5] vhost: introduce wrappers to set guest notifiers for virtio device Dima Stepanov
2020-05-04 0:36 ` Raphael Norwitz
2020-05-06 8:54 ` Dima Stepanov
2020-05-11 3:03 ` Jason Wang
2020-05-11 8:55 ` Dima Stepanov
2020-04-30 13:36 ` [PATCH v2 3/5] vhost-user-blk: add mechanism to track the guest notifiers init state Dima Stepanov
2020-05-04 1:06 ` Raphael Norwitz
2020-05-06 8:51 ` Dima Stepanov
2020-04-30 13:36 ` [PATCH v2 4/5] vhost: check vring address before calling unmap Dima Stepanov
2020-05-04 1:13 ` Raphael Norwitz
2020-05-11 3:05 ` Jason Wang
2020-05-11 9:11 ` Dima Stepanov
2020-05-12 3:26 ` Jason Wang
2020-05-12 9:08 ` Dima Stepanov
2020-05-13 3:00 ` Jason Wang
2020-05-13 9:36 ` Dima Stepanov
2020-05-14 7:28 ` Jason Wang
2020-04-30 13:36 ` [PATCH v2 5/5] vhost: add device started check in migration set log Dima Stepanov
2020-05-06 22:08 ` Raphael Norwitz
2020-05-07 7:15 ` Michael S. Tsirkin
2020-05-07 15:35 ` Dima Stepanov
2020-05-11 0:03 ` Raphael Norwitz
2020-05-11 9:43 ` Dima Stepanov
2020-05-11 3:15 ` Jason Wang
2020-05-11 9:25 ` Dima Stepanov
2020-05-12 3:32 ` Jason Wang
2020-05-12 3:47 ` Li Feng
2020-05-12 9:23 ` Dima Stepanov
2020-05-12 9:35 ` Dima Stepanov
2020-05-13 3:20 ` Jason Wang
2020-05-13 9:39 ` Dima Stepanov
2020-05-13 4:15 ` Michael S. Tsirkin
2020-05-13 5:56 ` Jason Wang
2020-05-13 9:47 ` Dima Stepanov
2020-05-14 7:34 ` Jason Wang
2020-05-15 16:54 ` Dima Stepanov
2020-05-16 3:20 ` Li Feng
2020-05-18 2:52 ` Jason Wang
2020-05-18 9:33 ` Dima Stepanov
2020-05-18 9:27 ` Dima Stepanov
2020-05-18 2:50 ` Jason Wang
2020-05-18 9:41 ` Dima Stepanov
2020-05-18 9:53 ` Dr. David Alan Gilbert
2020-05-19 9:07 ` Dima Stepanov
2020-05-19 10:24 ` Dr. David Alan Gilbert
2020-05-19 9:59 ` Michael S. Tsirkin [this message]
2020-05-19 9:13 ` Dima Stepanov
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