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scsi: revert change to scsi_req_cancel_async and add assertions 

Fam Zheng noticed that the change in commit 36896bf ("scsi: always call
notifier on async cancellation", 2015-12-16) could cause a leak of
the request; scsi_req_cancel_async now calls scsi_req_ref
multiple times for multiple cancellations, but there is only
one call to scsi_req_cancel_complete.

So revert the patch and instead assert that the problematic case (a call
to scsi_req_cancel_async after the aiocb has been completed) cannot
happen.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-12-18 09:54:53 +01:00
parent 5a57acb66f
commit 3daa41078a
1 changed files with 11 additions and 0 deletions
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11
hw/scsi/scsi-bus.c
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@ -1759,6 +1759,15 @@ void scsi_req_cancel_async(SCSIRequest *req, Notifier *notifier)
if (notifier) { if (notifier) {
notifier_list_add(&req->cancel_notifiers, notifier); notifier_list_add(&req->cancel_notifiers, notifier);
} }
if (req->io_canceled) {
/* A blk_aio_cancel_async is pending; when it finishes,
* scsi_req_cancel_complete will be called and will
* call the notifier we just added. Just wait for that.
*/
assert(req->aiocb);
return;
}
/* Dropped in scsi_req_cancel_complete. */
scsi_req_ref(req); scsi_req_ref(req);
scsi_req_dequeue(req); scsi_req_dequeue(req);
req->io_canceled = true; req->io_canceled = true;
@ -1775,6 +1784,8 @@ void scsi_req_cancel(SCSIRequest *req)
if (!req->enqueued) { if (!req->enqueued) {
return; return;
} }
assert(!req->io_canceled);
/* Dropped in scsi_req_cancel_complete. */
scsi_req_ref(req); scsi_req_ref(req);
scsi_req_dequeue(req); scsi_req_dequeue(req);
req->io_canceled = true; req->io_canceled = true;