On Mon, Aug 24, 2020 at 10:26:55AM +0800, Lu Baolu wrote: > Hi Jacob, > > On 8/22/20 12:35 PM, Jacob Pan wrote: > > There can be multiple users of an IOASID, each user could have hardware > > contexts associated with the IOASID. In order to align lifecycles, > > reference counting is introduced in this patch. It is expected that when > > an IOASID is being freed, each user will drop a reference only after its > > context is cleared. > > > > Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com> [...] > > +/** > > * ioasid_find - Find IOASID data > > * @set: the IOASID set > > * @ioasid: the IOASID to find > > Do you need to increase the refcount of the found ioasid and ask the > caller to drop it after use? Otherwise, the ioasid might be freed > elsewhere.
ioasid_find() takes a getter function as parameter, which ensures that the returned data is valid. It fetches the IOASID data under rcu_read_lock() and calls the getter on the private data (for example mmget_not_zero() for bare-metal SVA). Given that, I don't think returning with a reference to the IOASID is necessary. The IOASID may be freed once ioasid_find() returns but not the returned data. Thanks, Jean _______________________________________________ iommu mailing list email@example.com https://lists.linuxfoundation.org/mailman/listinfo/iommu