Commit de0fbe64 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

job: Use AIO_WAIT_WHILE() in job_finish_sync() 



job_finish_sync() needs to release the AioContext lock of the job before
calling aio_poll(). Otherwise, callbacks called by aio_poll() would
possibly take the lock a second time and run into a deadlock with a
nested AIO_WAIT_WHILE() call.

Also, job_drain() without aio_poll() isn't necessarily enough to make
progress on a job, it could depend on bottom halves to be executed.

Combine both open-coded while loops into a single AIO_WAIT_WHILE() call
that solves both of these problems.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
parent 30c070a5

job.c

+6 −8
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include "qemu/job.h"

#include "qemu/id.h"

#include "qemu/main-loop.h"

#include "block/aio-wait.h"

#include "trace-root.h"

#include "qapi/qapi-events-job.h"
@@ -962,6 +963,7 @@ void job_complete(Job *job, Error **errp) 
int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)

{

    Error *local_err = NULL;

    AioWait dummy_wait = {};

    int ret;



    job_ref(job);
@@ -974,14 +976,10 @@ int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp) 
        job_unref(job);

        return -EBUSY;

    }

    /* job_drain calls job_enter, and it should be enough to induce progress

     * until the job completes or moves to the main thread. */

    while (!job->deferred_to_main_loop && !job_is_completed(job)) {

        job_drain(job);

    }

    while (!job_is_completed(job)) {

        aio_poll(qemu_get_aio_context(), true);

    }



    AIO_WAIT_WHILE(&dummy_wait, job->aio_context,

                   (job_drain(job), !job_is_completed(job)));



    ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;

    job_unref(job);

    return ret;