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drbd: fix request leak introduced by locking/atomic, kref: Kill kref_sub()

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When killing kref_sub(), the unconditional additional kref_get()
was not properly paired with the necessary kref_put(), causing
a leak of struct drbd_requests (~ 224 Bytes) per submitted bio,
and breaking DRBD in general, as the destructor of those "drbd_requests"
does more than just the mempoll_free().

Fixes: bdfafc4ffd ("locking/atomic, kref: Kill kref_sub()")
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: stable@vger.kernel.org # v4.11
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Lars Ellenberg 2017-05-11 10:21:46 +02:00 committed by Jens Axboe
parent ed6565e734
commit a00ebd1cf1
1 changed files with 15 additions and 12 deletions
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27
drivers/block/drbd/drbd_req.c
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@ -315,24 +315,32 @@ void drbd_req_complete(struct drbd_request *req, struct bio_and_error *m)
}
/* still holds resource->req_lock */
static int drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)
static void drbd_req_put_completion_ref(struct drbd_request *req, struct bio_and_error *m, int put)
{
struct drbd_device *device = req->device;
D_ASSERT(device, m || (req->rq_state & RQ_POSTPONED));
if (!put)
return;
if (!atomic_sub_and_test(put, &req->completion_ref))
return 0;
return;
drbd_req_complete(req, m);
/* local completion may still come in later,
* we need to keep the req object around. */
if (req->rq_state & RQ_LOCAL_ABORTED)
return;
if (req->rq_state & RQ_POSTPONED) {
/* don't destroy the req object just yet,
* but queue it for retry */
drbd_restart_request(req);
return 0;
return;
}
return 1;
kref_put(&req->kref, drbd_req_destroy);
}
static void set_if_null_req_next(struct drbd_peer_device *peer_device, struct drbd_request *req)
@ -519,12 +527,8 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
if (req->i.waiting)
wake_up(&device->misc_wait);
if (c_put) {
if (drbd_req_put_completion_ref(req, m, c_put))
kref_put(&req->kref, drbd_req_destroy);
} else {
kref_put(&req->kref, drbd_req_destroy);
}
drbd_req_put_completion_ref(req, m, c_put);
kref_put(&req->kref, drbd_req_destroy);
}
static void drbd_report_io_error(struct drbd_device *device, struct drbd_request *req)
@ -1366,8 +1370,7 @@ nodata:
}
out:
if (drbd_req_put_completion_ref(req, &m, 1))
kref_put(&req->kref, drbd_req_destroy);
drbd_req_put_completion_ref(req, &m, 1);
spin_unlock_irq(&resource->req_lock);
/* Even though above is a kref_put(), this is safe.