* Peter Xu (pet...@redhat.com) wrote:
> It's efficient, but hackish to call yank unregister calls in channel_close(),
> especially it'll be hard to debug when qemu crashed with some yank function
> leaked.
>
> Remove that hack, but instead explicitly unregister yank functions at the
> places where needed, they are:
>
> (on src)
> - migrate_fd_cleanup
> - postcopy_pause
>
> (on dst)
> - migration_incoming_state_destroy
> - postcopy_pause_incoming
>
> Some small helpers are introduced to achieve this task. One of them is called
> migration_file_get_ioc(), which tries to fetch the ioc out of the qemu file.
> It's a bit tricky because qemufile is also used for savevm/loadvm. We need to
> check for NULL to bypass those. Please see comment above that helper for more
> information.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
Yes
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
although....
> ---
> migration/migration.c | 5 +++++
> migration/qemu-file-channel.c | 3 ---
> migration/qemu-file.c | 12 ++++++++++++
> migration/qemu-file.h | 2 ++
> migration/savevm.c | 7 +++++++
> migration/yank_functions.c | 14 ++++++++++++++
> migration/yank_functions.h | 1 +
> 7 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 4f48cde796..65b8c2eb52 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -59,6 +59,7 @@
> #include "multifd.h"
> #include "qemu/yank.h"
> #include "sysemu/cpus.h"
> +#include "yank_functions.h"
>
> #define MAX_THROTTLE (128 << 20) /* Migration transfer speed
> throttling */
>
> @@ -273,6 +274,7 @@ void migration_incoming_state_destroy(void)
> }
>
> if (mis->from_src_file) {
> + migration_ioc_unregister_yank_from_file(mis->from_src_file);
> qemu_fclose(mis->from_src_file);
> mis->from_src_file = NULL;
> }
> @@ -1811,6 +1813,7 @@ static void migrate_fd_cleanup(MigrationState *s)
> * Close the file handle without the lock to make sure the
> * critical section won't block for long.
> */
> + migration_ioc_unregister_yank_from_file(tmp);
> qemu_fclose(tmp);
> }
>
> @@ -3337,6 +3340,8 @@ static MigThrError postcopy_pause(MigrationState *s)
>
> /* Current channel is possibly broken. Release it. */
> assert(s->to_dst_file);
> + /* Unregister yank for current channel */
> + migration_ioc_unregister_yank_from_file(s->to_dst_file);
> qemu_mutex_lock(&s->qemu_file_lock);
> file = s->to_dst_file;
> s->to_dst_file = NULL;
> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index 2f8b1fcd46..bb5a5752df 100644
> --- a/migration/qemu-file-channel.c
> +++ b/migration/qemu-file-channel.c
> @@ -107,9 +107,6 @@ static int channel_close(void *opaque, Error **errp)
> int ret;
> QIOChannel *ioc = QIO_CHANNEL(opaque);
> ret = qio_channel_close(ioc, errp);
> - if (OBJECT(ioc)->ref == 1) {
> - migration_ioc_unregister_yank(ioc);
> - }
> object_unref(OBJECT(ioc));
> return ret;
> }
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index ada58c94dd..b32ff35e73 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -854,3 +854,15 @@ void qemu_file_set_blocking(QEMUFile *f, bool block)
> f->ops->set_blocking(f->opaque, block, NULL);
> }
> }
> +
> +/*
> + * Return the ioc object if it's a migration channel. Note: it can return
> NULL
> + * for callers passing in a non-migration qemufile. E.g. see
> qemu_fopen_bdrv()
> + * and its usage in e.g. load_snapshot(). So we need to check against NULL
> + * before using it. If without the check, migration_incoming_state_destroy()
> + * could fail for load_snapshot().
> + */
> +QIOChannel *migration_file_get_ioc(QEMUFile *file)
> +{
> + return file->has_ioc ? QIO_CHANNEL(file->opaque) : NULL;
> +}
Do you think this should go in the previous patch where you created
has_ioc? Also the name is weird, qemu_file is probably right for
everything in here.
Dave
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index 80d0e79fd1..59f3f78e8b 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -27,6 +27,7 @@
>
> #include <zlib.h>
> #include "exec/cpu-common.h"
> +#include "io/channel.h"
>
> /* Read a chunk of data from a file at the given position. The pos argument
> * can be ignored if the file is only be used for streaming. The number of
> @@ -179,5 +180,6 @@ void ram_control_load_hook(QEMUFile *f, uint64_t flags,
> void *data);
> size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
> ram_addr_t offset, size_t size,
> uint64_t *bytes_sent);
> +QIOChannel *migration_file_get_ioc(QEMUFile *file);
>
> #endif
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 96b5e5d639..7b7b64bd13 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -65,6 +65,7 @@
> #include "qemu/bitmap.h"
> #include "net/announce.h"
> #include "qemu/yank.h"
> +#include "yank_functions.h"
>
> const unsigned int postcopy_ram_discard_version;
>
> @@ -2568,6 +2569,12 @@ static bool
> postcopy_pause_incoming(MigrationIncomingState *mis)
> /* Clear the triggered bit to allow one recovery */
> mis->postcopy_recover_triggered = false;
>
> + /*
> + * Unregister yank with either from/to src would work, since ioc behind
> it
> + * is the same
> + */
> + migration_ioc_unregister_yank_from_file(mis->from_src_file);
> +
> assert(mis->from_src_file);
> qemu_file_shutdown(mis->from_src_file);
> qemu_fclose(mis->from_src_file);
> diff --git a/migration/yank_functions.c b/migration/yank_functions.c
> index 23697173ae..1f35ba3512 100644
> --- a/migration/yank_functions.c
> +++ b/migration/yank_functions.c
> @@ -14,6 +14,7 @@
> #include "qemu/yank.h"
> #include "io/channel-socket.h"
> #include "io/channel-tls.h"
> +#include "qemu-file.h"
>
> void migration_yank_iochannel(void *opaque)
> {
> @@ -46,3 +47,16 @@ void migration_ioc_unregister_yank(QIOChannel *ioc)
> QIO_CHANNEL(ioc));
> }
> }
> +
> +void migration_ioc_unregister_yank_from_file(QEMUFile *file)
> +{
> + QIOChannel *ioc = migration_file_get_ioc(file);
> +
> + if (ioc) {
> + /*
> + * For migration qemufiles, we'll always reach here. Though we'll
> skip
> + * calls from e.g. savevm/loadvm as they don't use yank.
> + */
> + migration_ioc_unregister_yank(ioc);
> + }
> +}
> diff --git a/migration/yank_functions.h b/migration/yank_functions.h
> index 74c7f18c91..a7577955ed 100644
> --- a/migration/yank_functions.h
> +++ b/migration/yank_functions.h
> @@ -17,3 +17,4 @@
> void migration_yank_iochannel(void *opaque);
> void migration_ioc_register_yank(QIOChannel *ioc);
> void migration_ioc_unregister_yank(QIOChannel *ioc);
> +void migration_ioc_unregister_yank_from_file(QEMUFile *file);
> --
> 2.31.1
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
