diff options
author | Laurent Vivier <lvivier@redhat.com> | 2020-06-17 13:31:54 +0200 |
---|---|---|
committer | Dr. David Alan Gilbert <dgilbert@redhat.com> | 2020-06-17 17:48:39 +0100 |
commit | 7e89a1401a9674c9882948f05f4d17ea7be1c4eb (patch) | |
tree | 1090373a6623a9362ba18b80f0c8ff349ff39339 /migration/multifd.c | |
parent | 6bcd361a52e73889d2123033ce48450289a1933e (diff) |
migration: fix multifd_send_pages() next channel
multifd_send_pages() loops around the available channels,
the next channel to use between two calls to multifd_send_pages() is stored
inside a local static variable, next_channel.
It works well, except if the number of channels decreases between two calls
to multifd_send_pages(). In this case, the loop can try to access the
data of a channel that doesn't exist anymore.
The problem can be triggered if we start a migration with a given number of
channels and then we cancel the migration to restart it with a lower number.
This ends generally with an error like:
qemu-system-ppc64: .../util/qemu-thread-posix.c:77: qemu_mutex_lock_impl: Assertion `mutex->initialized' failed.
This patch fixes the error by capping next_channel with the current number
of channels before using it.
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20200617113154.593233-1-lvivier@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'migration/multifd.c')
-rw-r--r-- | migration/multifd.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/migration/multifd.c b/migration/multifd.c index 5a3e4d0d46..d0441202aa 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -415,6 +415,12 @@ static int multifd_send_pages(QEMUFile *f) } qemu_sem_wait(&multifd_send_state->channels_ready); + /* + * next_channel can remain from a previous migration that was + * using more channels, so ensure it doesn't overflow if the + * limit is lower now. + */ + next_channel %= migrate_multifd_channels(); for (i = next_channel;; i = (i + 1) % migrate_multifd_channels()) { p = &multifd_send_state->params[i]; |