Hello Everyone, In many cases, if qemu has a network connection (qmp, migration, chardev, etc.) to some other server and that server dies or hangs, qemu hangs too. These patches introduce the new 'yank' out-of-band qmp command to recover from these kinds of hangs. The different subsystems register callbacks which get executed with the yank command. For example the callback can shutdown() a socket. This is intended for the colo use-case, but it can be used for other things too of course.
Regards, Lukas Straub v6: -add Reviewed-by and Acked-by tags -rebase on master -lots of changes in nbd due to rebase -only take maintainership of util/yank.c and include/qemu/yank.h (Daniel P. Berrangé) -fix a crash discovered by the newly added chardev test -fix the test itself v5: -move yank.c to util/ -move yank.h to include/qemu/ -add license to yank.h -use const char* -nbd: use atomic_store_release and atomic_load_aqcuire -io-channel: ensure thread-safety and document it -add myself as maintainer for yank v4: -fix build errors... v3: -don't touch softmmu/vl.c, use __contructor__ attribute instead (Paolo Bonzini) -fix build errors -rewrite migration patch so it actually passes all tests v2: -don't touch io/ code anymore -always register yank functions -'yank' now takes a list of instances to yank -'query-yank' returns a list of yankable instances Lukas Straub (9): Introduce yank feature block/nbd.c: Add yank feature chardev/char-socket.c: Add yank feature migration: Add yank feature io/channel-tls.c: make qio_channel_tls_shutdown thread-safe io: Document thread-safety of qio_channel_shutdown MAINTAINERS: Add myself as maintainer for yank feature chardev/char.c: Check for duplicate id before creating chardev tests/test-char.c: Wait for the chardev to connect in char_socket_client_dupid_test MAINTAINERS | 6 ++ block/nbd.c | 123 +++++++++++++---------- chardev/char-socket.c | 24 +++++ chardev/char.c | 11 ++- include/io/channel.h | 2 + include/qemu/yank.h | 79 +++++++++++++++ io/channel-tls.c | 6 +- migration/channel.c | 12 +++ migration/migration.c | 18 +++- migration/multifd.c | 10 ++ migration/qemu-file-channel.c | 6 ++ migration/savevm.c | 2 + qapi/misc.json | 45 +++++++++ tests/Makefile.include | 2 +- tests/test-char.c | 1 + util/Makefile.objs | 1 + util/yank.c | 179 ++++++++++++++++++++++++++++++++++ 17 files changed, 469 insertions(+), 58 deletions(-) create mode 100644 include/qemu/yank.h create mode 100644 util/yank.c -- 2.20.1
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