On 2024/11/6 21:36, Leon Romanovsky wrote: > 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. > Sure, thanks Junxian >> >> Junxian >> >>> Thanks >>> >>>> >>>> -- >>>> 2.33.0 >>>> >>>>
