Hi, Le jeudi 30 janvier 2014 à 01:33 +0200, Eli Cohen a écrit : > On Wed, Jan 29, 2014 at 09:48:43PM +0100, Yann Droneaud wrote: > Yann, > thanks for reviewing, your comments are helpful :-) > > > > > 12 digits identifier are the norm for kernel. Please update your git > > configuration: > > > > git config --global core.abbrev 12 > > > > See http://lwn.net/Articles/571980/ > > http://blog.cuviper.com/2013/11/10/how-short-can-git-abbreviate/ > > > > > libmlx5 and mlx5_ib since it defines a different value to the number of micro > > > UARs per page, leading to wrong calculation in libmlx5. This patch defines > > > struct mlx5_ib_alloc_ucontext_req_v2 as an extension to struct > > > mlx5_ib_alloc_ucontext_req. The extended size is determined in > > > mlx5_ib_alloc_ucontext() and in case of old library we use uuarn 0 which works > > > fine. For new libraries we use the more sophisticated allocation algorithm. > > > > > > Fixes: c1be523 ('Fix micro UAR allocator') > > ^^^^^^^ > > Likewise > > Will fix. > > > > I'm not sure how this could work without subtracting sizeof(struct > > ib_uverbs_cmd_hdr). > > struct ib_uverbs_get_context happens to have the same size as struct > ib_uverbs_cmd_hdr so it passed all my sanity tests. Correct, will fix > that too. > > > > As I explained in "Re: [PATCHv4 for-3.13 00/10] create_flow/destroy_flow > > fixes for v3.13" [1] ib_uverbs_write() does not decrement input length: > > it gives hdr.in_words * 4 to the uverbs function, here > > ib_uverbs_get_context(). Then, the function built struct ib_udata > > without taking care of the extra bytes count in in_len: > > > > struct ib_uverbs_get_context cmd; > > ... > > INIT_UDATA(&udata, buf + sizeof cmd, > > (unsigned long) cmd.response + sizeof resp, > > in_len - sizeof cmd, out_len - sizeof resp); > > So this just seems broken and the fix is to do the subtraction here so > the hardware driver gets the correct size without needing to subtract > the extra bytes, like this: > INIT_UDATA(&udata, buf + sizeof cmd, > (unsigned long) cmd.response + sizeof resp, > in_len - sizeof cmd - sizeof (struct ib_uverbs_cmd_hdr), > out_len - sizeof resp); > > And the hardware driver gets the correct size for its struct. > It's not the place to address the issue: the proper fix is to subtract it in ib_uverbs_write(). I have a patch for this but I'm not going to submit it for 3.14: it's part of a patchset that need testing and polishing. I will submit this large patchset for 3.15 (after v3.14-rc1). So you have to subtract the header size in your driver, just like mthca does. And don't worry I will take care of removing it in my patch that remove the header size from input length. > > > > Driver mthca does some handling which look like to what's proposed in > > your patch, but takes care of subtracting the header size from the input > > length, see mthca_reg_user_mr()[2]. > > > > [1] > > <http://marc.info/?i=1387493822.11925.217.camel@localhost.localdomain> > > > > [2] > > <http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/infiniband/hw/mthca/mthca_provider.c?id=0e47c969c65e213421450c31043353ebe3c67e0c#n988> > > > > > + if (reqlen == sizeof(struct mlx5_ib_alloc_ucontext_req)) > > > + ver = 0; > > > + else if (reqlen == sizeof(struct mlx5_ib_alloc_ucontext_req_v2)) > > > + ver = 2; > > > + else > > > + return ERR_PTR(-EINVAL); > > > + > > > > Doing so introduce a subtle regression: there was no check on the length > > before, so it was legal to pass a input buffer far larger than needed, > > aka. trailing garbage. > > > > With such new test in place, it's no more allowed, and this is a > > regression. It's not a big issue, but a little departure from current > > behavor. > Well it's a regression if there was out there another library for mlx5 > out there which misbehaves and there is any as far as I know. So I > think it's safe to add this strict check. Yes I think so. But as I'm used to write it here, there's no clear line drawn: where is the ABI that we should enforce ? Is it the kernel uverbs data structure for response and request or libuverbs/lib<hw> ? In the first case, your change add a regression, in the second case, it's not. It's just a theoretical question. In practice, as you wrote, we can say there's no other library that implement the userspace part of mlx5 rdma driver. > > > > BTW, this is the correct way to handle the request, every other uverbs > > functions should behave like this, eg. being strict on its accepted > > input. > > > > > + err = ib_copy_from_udata(&req, udata, reqlen); > > > if (err) > > > return ERR_PTR(err); > > > > > > + if (req.flags || req.reserved) > > > + return ERR_PTR(-EINVAL); > > > + > > > > Just like this :) > > > > > if (req.total_num_uuars > MLX5_MAX_UUARS) > > > return ERR_PTR(-ENOMEM); > > > > > > @@ -626,6 +640,7 @@ static struct ib_ucontext *mlx5_ib_alloc_ucontext(struct ib_device *ibdev, > > > if (err) > > > goto out_uars; > > > > > > + uuari->ver = ver; > > > uuari->num_low_latency_uuars = req.num_low_latency_uuars; > > > uuari->uars = uars; > > > uuari->num_uars = num_uars; > > > diff --git a/drivers/infiniband/hw/mlx5/qp.c b/drivers/infiniband/hw/mlx5/qp.c > > > index 492dc33..300475c 100644 > > > --- a/drivers/infiniband/hw/mlx5/qp.c > > > +++ b/drivers/infiniband/hw/mlx5/qp.c > > > @@ -430,11 +430,17 @@ static int alloc_uuar(struct mlx5_uuar_info *uuari, > > > break; > > > > > > case MLX5_IB_LATENCY_CLASS_MEDIUM: > > > - uuarn = alloc_med_class_uuar(uuari); > > > + if (uuari->ver < 2) > > > + uuarn = -ENOMEM; > > > > In the commit message, you specified that uuarn is set to 0 when v1 is > > used. But here it's set to -ENOMEM. > > > If you look at qp.c you can see that the code falls back from high to > medium to low class. Low class always succeeds and gives 0. > It was not clear from the commit message. > > > + else > > > + uuarn = alloc_med_class_uuar(uuari); > > > break; > > > > > > case MLX5_IB_LATENCY_CLASS_HIGH: > > > - uuarn = alloc_high_class_uuar(uuari); > > > + if (uuari->ver < 2) > > > + uuarn = -ENOMEM; > > > > Likewise. > > > > > + else > > > + uuarn = alloc_high_class_uuar(uuari); > > > break; > > > Regards -- Yann Droneaud OPTEYA -- 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
