On 22/01/2015 15:28, Yann Droneaud wrote: > This patch ensures the extended QUERY_DEVICE uverbs request's > comp_mask has only known values. If userspace returns unknown > features, -EINVAL will be returned, allowing to probe/discover > which features are currently supported by the kernel. This probing process will be much more cumbersome than it needs to be because userspace will have to call QUERY_DEVICE repetitively with different comp_mask fields until it finds out the exact set of supported bits. > Moreover, it also ensure the requested features set in comp_mask > are sequentially set, not skipping intermediate features, eg. the > "highest" requested feature also request all the "lower" ones. > This way each new feature will have to be stacked on top of the > existing ones: this is especially important for the request and > response data structures where fields are added after the > current ones when expanded to support a new feature. I think it is perfectly acceptable that not all drivers will implement all available features, and so you shouldn't enforce this requirement. Also, it makes the comp_mask nothing more than a wasteful version number between 0 and 63. In the specific case of QUERY_DEVICE you might argue that there isn't any need for input comp_mask, only for output, and then you may enforce the input comp_mask will always be zero. However, you will in any case need to be able to extended the size of the response in the future. > > Link: http://mid.gmane.org/cover.1421931555.git.ydroneaud@xxxxxxxxxx > Cc: Sagi Grimberg <sagig@xxxxxxxxxxxx> > Cc: Shachar Raindel <raindel@xxxxxxxxxxxx> > Cc: Eli Cohen <eli@xxxxxxxxxxxx> > Cc: Haggai Eran <haggaie@xxxxxxxxxxxx> > Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx> > --- > drivers/infiniband/core/uverbs_cmd.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c > index 8668b328b7e6..80a1c90f1dbf 100644 > --- a/drivers/infiniband/core/uverbs_cmd.c > +++ b/drivers/infiniband/core/uverbs_cmd.c > @@ -3313,6 +3313,12 @@ int ib_uverbs_ex_query_device(struct ib_uverbs_file *file, > if (err) > return err; > > + if (cmd.comp_mask & (cmd.comp_mask + 1)) > + return -EINVAL; > + > + if (cmd.comp_mask & ~(__u32)IB_USER_VERBS_EX_QUERY_DEVICE_ODP) > + return -EINVAL; > + > if (cmd.reserved) > return -EINVAL; > > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
