On Wed, Nov 06, 2024 at 09:12:47PM +0800, Junxian Huang wrote: > > > On 2024/11/6 20:08, Leon Romanovsky wrote: > > On Tue, Nov 05, 2024 at 08:08:39PM +0800, Junxian Huang wrote: > >> ib_map_mr_sg() and ib_map_mr_sg_pi() allow ULPs to specify NULL as > >> the sg_offset/data_sg_offset/meta_sg_offset arguments. Drivers who > >> need to derefernce these arguments have to add NULL pointer checks > >> to avoid crashing the kernel. > >> > >> This can be optimized by adding dummy sg_offset pointer to these > >> two APIs. When the sg_offset arguments are NULL, pass the pointer > >> of dummy to drivers. Drivers can always get a valid pointer, so no > >> need to add NULL pointer checks. > >> > >> Junxian Huang (2): > >> RDMA/core: Add dummy sg_offset pointer for ib_map_mr_sg() and > >> ib_map_mr_sg_pi() > >> RDMA: Delete NULL pointer checks for sg_offset in .map_mr_sg ops > >> > >> drivers/infiniband/core/verbs.c | 12 +++++++++--- > >> drivers/infiniband/hw/mlx5/mr.c | 18 ++++++------------ > >> drivers/infiniband/sw/rdmavt/trace_mr.h | 2 +- > >> 3 files changed, 16 insertions(+), 16 deletions(-) > > > > So what does this change give us? > > We have same functionality, same number of lines, same everything ... > > > > Actually this is inspired by an hns bug. When ib_map_mr_sg() passes a NULL > sg_offset pointer to hns_roce_map_mr_sg(), we dereference this pointer > without a NULL check. > > Of course we can fix it by adding NULL check in hns, but I think this > patch may be a better solution since the sg_offset is guaranteed to be > a valid pointer. This could benefit future drivers who also want to > dereference sg_offset, they won't need to care about NULL checks. Let's fix hns please. We are moving away from SG in RDMA. > > Junxian > > > Thanks > > > >> > >> -- > >> 2.33.0 > >> > >>
