On 09/03/2019 04:02, Kangjie Lu wrote: > idr_find may return NULL, so check its return value and return an > error code. > > Signed-off-by: Kangjie Lu <[email protected]> > --- > drivers/firmware/arm_scmi/driver.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/firmware/arm_scmi/driver.c > b/drivers/firmware/arm_scmi/driver.c > index 8f952f2f1a29..35faa203d549 100644 > --- a/drivers/firmware/arm_scmi/driver.c > +++ b/drivers/firmware/arm_scmi/driver.c > @@ -709,6 +709,8 @@ scmi_mbox_chan_setup(struct scmi_info *info, struct > device *dev, int prot_id) > > if (scmi_mailbox_check(np)) { > cinfo = idr_find(&info->tx_idr, SCMI_PROTOCOL_BASE); > + if (!cinfo) > + return -EINVAL; > goto idr_alloc; > } > >
I don't believe this situation can ever actually occur. The SCMI_PROTOCOL_BASE id is reserved just after the IDR is created in scmi_probe() in the first call to scmi_mbox_chan_setup(). That first call can't enter the above if() block because the scmi_mailbox_check() call has already been checked in scmi_probe(). It is only when processing the children in subsequent calls to scmi_mbox_chan_setup() that the check is on another node and so might fail. But by this time the SCMI_PROTOCOL_BASE id must exist. So there shouldn't be any way of reaching the situation where the IDR doesn't contain SCMI_PROTOCOL_BASE and idr_find() returns NULL. Having said that it did take me a while to understand the code well enough to reason that, and the above return should be handled appropriately, so you can add my Reviewed-by. But it would be worth expanding the commit message pointing out that there isn't actually a bug (yet). Steve
