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Date: Fri, 18 Dec 2015 08:57:16 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PULL 43/45] scsi: always call notifier on async
 cancellation
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org

On Thu, 12/17 18:46, Paolo Bonzini wrote:
> This was found by code inspection.  If the request is cancelled twice,
> the notifier is never called on the second cancellation request,
> and hence for example a TMF might never finish.
> 
> All the calls in scsi_req_cancel_async are idempotent, so the change
> is safe.
> 
> Reviewed-by: Fam Zheng <famz@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Message-Id: <1450290827-30508-2-git-send-email-pbonzini@redhat.com>
> ---
>  hw/scsi/scsi-bus.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
> index a600074..00bddc9 100644
> --- a/hw/scsi/scsi-bus.c
> +++ b/hw/scsi/scsi-bus.c
> @@ -1759,9 +1759,6 @@ void scsi_req_cancel_async(SCSIRequest *req, Notifier *notifier)
>      if (notifier) {
>          notifier_list_add(&req->cancel_notifiers, notifier);
>      }
> -    if (req->io_canceled) {
> -        return;
> -    }
>      scsi_req_ref(req);
>      scsi_req_dequeue(req);
>      req->io_canceled = true;
> -- 
> 2.5.0
> 
> 
> 

Oh hang on, in scsi_req_dequeue, if req->enqueued is already false, the
matching scsi_req_unref is never called. Won't it be leaked?

Fam