On 5/31/2022 12:31 PM, Andrew Morton wrote:
On Tue, 31 May 2022 10:56:23 -0500 Alex Sierra <alex.sie...@amd.com> wrote:new ioctl cmd added to query zone device type. This will be used once the test_hmm adds zone device coherent type. @@ -1026,6 +1027,15 @@ static int dmirror_snapshot(struct dmirror *dmirror, return ret; }+static int dmirror_get_device_type(struct dmirror *dmirror,+ struct hmm_dmirror_cmd *cmd) +{ + mutex_lock(&dmirror->mutex); + cmd->zone_device_type = dmirror->mdevice->zone_device_type; + mutex_unlock(&dmirror->mutex);What does the locking here do? Presumably cmd->zone_device_type can become out of date the instant the mutex is released, so what was the point in taking the mutex?
Actually this is not used at all. Thanks for finding it. Honestly, I don't remember what we used this type request for.
I will remove all related code and send a new patch series version. Regards, Alex Sierra
And does it make sense to return potentially out-of-date info to userspace? Perhaps this interface simply shouldn't exist?
