There is (mostly theoretical) race between removal of a scsi device and
scsi_dma_restart_bh.
It used to be easier to hit this race prior to my / Paulo's patch series
that added rcu to scsi bus device handling code, but IMHO this race
should still be possible to hit, at least in theory.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1854811
Fix it anyway with a patch that was proposed by Paulo in the above bugzilla.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
hw/scsi/scsi-bus.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index b901e701f0..edb5c3492a 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -170,6 +170,8 @@ static void scsi_dma_restart_bh(void *opaque)
scsi_req_unref(req);
}
aio_context_release(blk_get_aio_context(s->conf.blk));
+ /* Drop the reference that was acquired in scsi_dma_restart_cb */
+ object_unref(OBJECT(s));
}
void scsi_req_retry(SCSIRequest *req)
@@ -188,6 +190,8 @@ static void scsi_dma_restart_cb(void *opaque, int running,
RunState state)
}
if (!s->bh) {
AioContext *ctx = blk_get_aio_context(s->conf.blk);
+ /* The reference is dropped in scsi_dma_restart_bh.*/
+ object_ref(OBJECT(s));
s->bh = aio_bh_new(ctx, scsi_dma_restart_bh, s);
qemu_bh_schedule(s->bh);
}