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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <1525701137-9384-2-git-send-email-lidongchen@tencent.com> (Lidong
	Chen's message of "Mon, 7 May 2018 21:52:17 +0800")
References: <1525701137-9384-1-git-send-email-lidongchen@tencent.com>
	<1525701137-9384-2-git-send-email-lidongchen@tencent.com>
Reply-To: quintela@redhat.com
Date: Tue, 08 May 2018 14:36:30 +0200
Message-ID: <877eoe8gtt.fsf@secure.laptop>
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Subject: Re: [Qemu-devel] [PATCH 2/2] migration: invoke qio_channel_yield
 only when qemu_in_coroutine()
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To: Lidong Chen <jemmy858585@gmail.com>
Cc: dgilbert@redhat.com, berrange@redhat.com, qemu-devel@nongnu.org, galsha@mellanox.com, aviadye@mellanox.com, adido@mellanox.com, Lidong Chen <lidongchen@tencent.com>

Lidong Chen <jemmy858585@gmail.com> wrote:
> when qio_channel_read return QIO_CHANNEL_ERR_BLOCK, the source qemu crash.
>
> The backtrace is:
>     (gdb) bt
>     #0  0x00007fb20aba91d7 in raise () from /lib64/libc.so.6
>     #1  0x00007fb20abaa8c8 in abort () from /lib64/libc.so.6
>     #2  0x00007fb20aba2146 in __assert_fail_base () from /lib64/libc.so.6
>     #3  0x00007fb20aba21f2 in __assert_fail () from /lib64/libc.so.6
>     #4  0x00000000008dba2d in qio_channel_yield (ioc=0x22f9e20, condition=G_IO_IN) at io/channel.c:460
>     #5  0x00000000007a870b in channel_get_buffer (opaque=0x22f9e20, buf=0x3d54038 "", pos=0, size=32768)
>         at migration/qemu-file-channel.c:83
>     #6  0x00000000007a70f6 in qemu_fill_buffer (f=0x3d54000) at migration/qemu-file.c:299
>     #7  0x00000000007a79d0 in qemu_peek_byte (f=0x3d54000, offset=0) at migration/qemu-file.c:562
>     #8  0x00000000007a7a22 in qemu_get_byte (f=0x3d54000) at migration/qemu-file.c:575
>     #9  0x00000000007a7c46 in qemu_get_be16 (f=0x3d54000) at migration/qemu-file.c:647
>     #10 0x0000000000796db7 in source_return_path_thread (opaque=0x2242280) at migration/migration.c:1794
>     #11 0x00000000009428fa in qemu_thread_start (args=0x3e58420) at util/qemu-thread-posix.c:504
>     #12 0x00007fb20af3ddc5 in start_thread () from /lib64/libpthread.so.0
>     #13 0x00007fb20ac6b74d in clone () from /lib64/libc.so.6
>
> This patch fixed by invoke qio_channel_yield only when qemu_in_coroutine().
>
> Signed-off-by: Lidong Chen <lidongchen@tencent.com>

Reviewed-by: Juan Quintela <quintela@redhat.com>

queued

> -            qio_channel_wait(ioc, G_IO_OUT);
> +            if (qemu_in_coroutine()) {
> +                qio_channel_yield(ioc, G_IO_OUT);
> +            } else {
> +                qio_channel_wait(ioc, G_IO_OUT);
> +            }

Dan, once that I am here, shouldn't this code be inside
qio_channel_wait()?  Or have a function that does it?

qio_channel_readv_all_eof() and qio_channel_writev_all() already have to use it.

Just wondering.