On Tue, Feb 10, 2015 at 03:20:46PM +0800, Bin Wu wrote: > From: Bin Wu <wu.wu...@huawei.com> > > When we tested the VM migartion between different hosts with NBD > devices, we found if we sent a cancel command after the drive_mirror > was just started, a coroutine re-enter error would occur. The stack > was as follow: > > (gdb) bt > 00) 0x00007fdfc744d885 in raise () from /lib64/libc.so.6 > 01) 0x00007fdfc744ee61 in abort () from /lib64/libc.so.6 > 02) 0x00007fdfca467cc5 in qemu_coroutine_enter (co=0x7fdfcaedb400, > opaque=0x0) > at qemu-coroutine.c:118 > 03) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedb400) at > qemu-coroutine-lock.c:59 > 04) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8, > to=0x7fdfcaedb400) at qemu-coroutine.c:96 > 05) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedb400, > opaque=0x0) > at qemu-coroutine.c:123 > 06) 0x00007fdfca467f6c in qemu_co_queue_run_restart (co=0x7fdfcaedbdc0) at > qemu-coroutine-lock.c:59 > 07) 0x00007fdfca467be5 in coroutine_swap (from=0x7fdfcaf3c4e8, > to=0x7fdfcaedbdc0) at qemu-coroutine.c:96 > 08) 0x00007fdfca467cea in qemu_coroutine_enter (co=0x7fdfcaedbdc0, > opaque=0x0) > at qemu-coroutine.c:123 > 09) 0x00007fdfca4a1fa4 in nbd_recv_coroutines_enter_all (s=0x7fdfcaef7dd0) at > block/nbd-client.c:41 > 10) 0x00007fdfca4a1ff9 in nbd_teardown_connection (client=0x7fdfcaef7dd0) at > block/nbd-client.c:50 > 11) 0x00007fdfca4a20f0 in nbd_reply_ready (opaque=0x7fdfcaef7dd0) at > block/nbd-client.c:92 > 12) 0x00007fdfca45ed80 in aio_dispatch (ctx=0x7fdfcae15e90) at aio-posix.c:144 > 13) 0x00007fdfca45ef1b in aio_poll (ctx=0x7fdfcae15e90, blocking=false) at > aio-posix.c:222 > 14) 0x00007fdfca448c34 in aio_ctx_dispatch (source=0x7fdfcae15e90, > callback=0x0, > user_data=0x0) at async.c:212 > 15) 0x00007fdfc8f2f69a in g_main_context_dispatch () from > /usr/lib64/libglib-2.0.so.0 > 16) 0x00007fdfca45c391 in glib_pollfds_poll () at main-loop.c:190 > 17) 0x00007fdfca45c489 in os_host_main_loop_wait (timeout=1483677098) at > main-loop.c:235 > 18) 0x00007fdfca45c57b in main_loop_wait (nonblocking=0) at main-loop.c:484 > 19) 0x00007fdfca25f403 in main_loop () at vl.c:2249 > 20) 0x00007fdfca266fc2 in main (argc=42, argv=0x7ffff517d638, > envp=0x7ffff517d790) at vl.c:4814 > > We find the nbd_recv_coroutines_enter_all function (triggered by a cancel > command or a network connection breaking down) will enter a coroutine which > is waiting for the sending lock. If the lock is still held by another > coroutine, > the entering coroutine will be added into the co_queue again. Latter, when the > lock is released, a coroutine re-enter error will occur. > > This bug can be fixed simply by delaying the setting of recv_coroutine as > suggested by paolo. After applying this patch, we have tested the cancel > operation in mirror phase looply for more than 5 hous and everything is fine. > Without this patch, a coroutine re-enter error will occur in 5 minutes. > > Signed-off-by: Bn Wu <wu.wu...@huawei.com> > --- > v2: fix the coroutine re-enter bug in NBD code, not in coroutine > infrastructure > as suggested by paolo and kevin. > --- > block/nbd-client.c | 25 +++++++++++++------------ > 1 file changed, 13 insertions(+), 12 deletions(-)
Thanks, applied to my block tree: https://github.com/stefanha/qemu/commits/block Stefan
pgp9PJ2TvAUtR.pgp
Description: PGP signature
