From: Leon Romanovsky <leon@xxxxxxxxxx> Date: Thu, 10 Apr 2025 16:27:06 +0300 > On Thu, Apr 10, 2025 at 02:58:28PM +0200, Larysa Zaremba wrote: >> On Thu, Apr 10, 2025 at 02:23:49PM +0300, Leon Romanovsky wrote: >>> On Thu, Apr 10, 2025 at 12:44:33PM +0200, Larysa Zaremba wrote: >>>> On Thu, Apr 10, 2025 at 11:21:37AM +0300, Leon Romanovsky wrote: >>>>> On Tue, Apr 08, 2025 at 02:47:51PM +0200, Larysa Zaremba wrote: >>>>>> From: Phani R Burra <phani.r.burra@xxxxxxxxx> >>>>>> >>>>>> Libeth will now support control queue setup and configuration APIs. >>>>>> These are mainly used for mailbox communication between drivers and >>>>>> control plane. >>>>>> >>>>>> Make use of the page pool support for managing controlq buffers. >>>>> >>>>> <...> >>>>> >>>>>> libeth-y := rx.o >>>>>> >>>>>> +obj-$(CONFIG_LIBETH_CP) += libeth_cp.o >>>>>> + >>>>>> +libeth_cp-y := controlq.o >>>>> >>>>> So why did you create separate module for it? >>>>> Now you have pci -> libeth -> libeth_cp -> ixd, with the potential races between ixd and libeth, am I right? >>>>> >>>> >>>> I am not sure what kind of races do you mean, all libeth modules themselves are >>>> stateless and will stay this way [0], all used data is owned by drivers. >>> >>> Somehow such separation doesn't truly work. There are multiple syzkaller >>> reports per-cycle where module A tries to access module C, which already >>> doesn't exist because it was proxied through module B. >> >> Are there similar reports for libeth and libie modules when iavf is enabled? > > To get such report, syzkaller should run on physical iavf, it looks like it doesn't. > Did I miss it here? > https://syzkaller.appspot.com/upstream/s/net > >> It is basically the same hierarchy. (iavf uses both libeth and libie, libie >> depends on libeth). >> >> I am just trying to understand, is this a regular situation or did I just mess >> smth up? > > My review comment was general one. It is almost impossible to review > this newly proposed architecture split for correctness. > >> >>> >>>> >>>> As for the module separation, I think there is no harm in keeping it modular. >>> >>> Syzkaller reports disagree with you. >>> >> >> Could you please share them? > > It is not an easy question to answer, because all these reports are complaining > about some wrong locking order or NULL-pointer access. You will never know if > it is because of programming or design error. > > As an approximate example, see commits a27c6f46dcec ("RDMA/bnxt_re: Fix an issue in bnxt_re_async_notifier") > and f0df225d12fc ("RDMA/bnxt_re: Add sanity checks on rdev validity"). > At the first glance, they look unrelated to our discussion, however > they can serve as an example or races between deinit/disable paths in > parent module vs. child. Unrelated. At first, you were talking about module dependencies, now you're talking about struct device etc dependencies, which is a completely different thing. As already said, libeth is stateless, so the latter one can't happen. The former one is impossible at all. As long as at least 1 child module is loaded, you can't unload the parent. And load/unload is serialized, see module core code. [...] >> We did not think this would be a problem, intel has a tradition of calling the >> modules pretty ambiguously. > > I know and it is worth to be changed. Out of scope of this series. Thanks, Olek
