Messages in this thread | | | From | NeilBrown <> | Date | Thu, 14 Jun 2018 08:29:28 +1000 | Subject | Re: [PATCH v2 01/25] staging: lustre: libcfs: restore UMP handling |
| |
On Wed, Jun 13 2018, James Simmons wrote:
>> > With the cleanup of the libcfs SMP handling all UMP handling >> > was removed. In the process now various NULL pointers and >> > empty fields are return in the UMP case which causes lustre >> > to crash hard. Restore the proper UMP handling so Lustre can >> > properly function. >> >> Can't we just get lustre to handle the NULL pointer? >> Is most cases, the pointer is accessed through an accessor function, and >> on !CONFIG_SMP, that can be a static inline that doesn't even look at >> the pointer. > > Lots of NULL pointer checks for a structure allocated at libcfs module > start and only cleaned up at libcfs removal is not a clean approach. > So I have thought about it and I have to ask why allocate a global > struct cfs_cpu_table. It could be made static and fill it in which would > avoid the whole NULL pointer issue. Plus for the UMP case why allocate > a new cfs_cpu_table with cfs_cpt_table_alloc() which is exactly like > the default UMP cfs_cpu_table. Instead we could just return the pointer > to the static default cfs_cpt_tab every time. We still have the NULL > ctb_cpumask field to deal with. Does that sound like a better solution > to you? Doug what do you think?
I'm not convinced there will be lots of NULL pointer checks - maybe one or two. Most the accesses to the structure are inside helper functions which are empty inlines in the UP build.
However I don't object to a static cfs_cpt_tab if that turns out to make some code simpler. I would want it to be clear up-front which code was simplified so that an informed decision could be made.
Thanks, NeilBrown
> >> I really think this is a step backwards. If you can identify specific >> problems caused by the current code, I'm sure we can fix them. >> >> > >> > Signed-off-by: James Simmons <uja.ornl@yahoo.com> >> > Signed-off-by: Amir Shehata <amir.shehata@intel.com> >> > Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-7734 >> >> This bug doesn't seem to mention this patch at all >> >> > Reviewed-on: http://review.whamcloud.com/18916 >> >> Nor does this review. > > Yeah its mutated so much from what is in the Intel tree. > I do believe it was the last patch to touch this. [unhandled content-type:application/pgp-signature] | |