On 06.08.21 21:16, Eric Blake wrote:
On Fri, Aug 06, 2021 at 11:38:48AM +0200, Max Reitz wrote:
Finalizing the job may cause its AioContext to change. This is noted by
job_exit(), which points at job_txn_apply() to take this fact into
account.
However, job_completed() does not necessarily invoke job_txn_apply()
(through job_completed_txn_success()), but potentially also
job_completed_txn_abort(). The latter stores the context in a local
variable, and so always acquires the same context at its end that it has
released in the beginning -- which may be a different context from the
one that job_exit() releases at its end. If it is different, qemu
aborts ("qemu_mutex_unlock_impl: Operation not permitted").
Is this a bug fix that needs to make it into 6.1?
Well, I only encountered it as part of this series (which I really don’t
think is 6.2 material at this point), and so I don’t know.
Can’t hurt, I suppose, but if we wanted this to be in 6.1, we’d better
have a specific test for it, I think.
Drop the local @outer_ctx variable from job_completed_txn_abort(), and
instead re-acquire the actual job's context at the end of the function,
so job_exit() will release the same.
Signed-off-by: Max Reitz <[email protected]>
---
job.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
The commit message makes sense, and does a good job at explaining the
change. I'm still a bit fuzzy on how jobs are supposed to play nice
with contexts,
I can relate :)
but since your patch matches the commit message, I'm
happy to give:
Reviewed-by: Eric Blake <[email protected]>
Thanks!
