Hi Jim,
> From: Harris, James R <james.r.har...@intel.com>
> Sent: Saturday, April 17, 2021 6:05 AM
> To: dev@dpdk.org; Xueming(Steven) Li <xuemi...@nvidia.com>
> Subject: Bug with commit 64051bb1 (devargs: unify scratch buffer storage)
>
> Hi,
>
> SPDK has identified a regression with commit 64051bb1 (devargs: unify scratch
> buffer storage). The issue seems to be with this part of the patch:
>
> @@ -276,15 +287,8 @@ rte_devargs_insert(struct rte_devargs **da)
> if (strcmp(listed_da->bus->name, (*da)->bus->name) == 0 &&
> strcmp(listed_da->name, (*da)->name) == 0) {
> /* device already in devargs list, must be updated */
> - listed_da->type = (*da)->type;
> - listed_da->policy = (*da)->policy;
> - free(listed_da->args);
> - listed_da->args = (*da)->args;
> - listed_da->bus = (*da)->bus;
> - listed_da->cls = (*da)->cls;
> - listed_da->bus_str = (*da)->bus_str;
> - listed_da->cls_str = (*da)->cls_str;
> - listed_da->data = (*da)->data;
> + rte_devargs_reset(listed_da);
> + *listed_da = **da;
> /* replace provided devargs with found one */
> free(*da);
> *da = listed_da;
>
>
> Previously the data members were copied one-by-one, preserving the pointers
> in the listed_da’s TAILQ_ENTRY. But after this patch, rte_devargs_reset()
> zeroes the entire rte_devargs structure, including the pointers in the
> TAILQ_ENTRY. If we do a subsequent rte_devargs_remove() on this same entry,
> we segfault since the TAILQ_ENTRY’s pointers are invalid. There could be
> similar segfaults with any subsequent rte_devargs_insert() calls that require
> iterating the global list of devargs entries.
>
> rte_devargs_insert() could manually copy the TAILQ_ENTRY pointers to *da
> before calling rte_devargs_reset() – that at least fixes the SPDK regression.
> But it’s not clear to me how many of the other rte_devargs_reset() callsites
> added by this patch also need to be changed in some way.
Thanks for reporting this issue, your fix should work. Rte_devargs_reset()
simply free and clear da->data field, not all of da.
I will send a patch to fix this, thanks again for pointing this out.
>
> Thanks,
>
> -Jim
>
