> -----Original Message-----
> From: Medvedkin, Vladimir <vladimir.medved...@intel.com>
> Sent: Thursday, July 16, 2020 7:00 PM
> To: Ruifeng Wang <ruifeng.w...@arm.com>; Bruce Richardson
> <bruce.richard...@intel.com>
> Cc: dev@dpdk.org; nd <n...@arm.com>; Honnappa Nagarahalli
> <honnappa.nagaraha...@arm.com>; Phil Yang <phil.y...@arm.com>
> Subject: Re: [PATCH] lpm: fix unchecked return value
>
> Hi Ruifeng,
>
> On 16/07/2020 06:19, Ruifeng Wang wrote:
> > Coverity complains about unchecked return value of
> rte_rcu_qsbr_dq_enqueue.
> > By default, defer queue size is big enough to hold all tbl8 groups.
> > When enqueue fails, return error to the user to indicate system issue.
> >
> > Coverity issue: 360832
> > Fixes: 8a9f8564e9f9 ("lpm: implement RCU rule reclamation")
> >
> > Signed-off-by: Ruifeng Wang <ruifeng.w...@arm.com>
> > ---
> > lib/librte_lpm/rte_lpm.c | 16 +++++++++++-----
> > 1 file changed, 11 insertions(+), 5 deletions(-)
> >
> > diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index
> > 2db9e16a2..a6d3a7894 100644
> > --- a/lib/librte_lpm/rte_lpm.c
> > +++ b/lib/librte_lpm/rte_lpm.c
> > @@ -532,11 +532,12 @@ tbl8_alloc(struct rte_lpm *lpm)
> > return group_idx;
> > }
> >
> > -static void
> > +static int
> > tbl8_free(struct rte_lpm *lpm, uint32_t tbl8_group_start)
> > {
> > struct rte_lpm_tbl_entry zero_tbl8_entry = {0};
> > struct __rte_lpm *internal_lpm;
> > + int rc = 0;
> >
> > internal_lpm = container_of(lpm, struct __rte_lpm, lpm);
> > if (internal_lpm->v == NULL) {
> > @@ -552,9 +553,13 @@ tbl8_free(struct rte_lpm *lpm, uint32_t
> tbl8_group_start)
> > __ATOMIC_RELAXED);
> > } else if (internal_lpm->rcu_mode == RTE_LPM_QSBR_MODE_DQ) {
> > /* Push into QSBR defer queue. */
> > - rte_rcu_qsbr_dq_enqueue(internal_lpm->dq,
> > + rc = rte_rcu_qsbr_dq_enqueue(internal_lpm->dq,
> > (void *)&tbl8_group_start);
>
> On failure rte_rcu_qsbr_dq_enqueue() returns 1 and sets rte_errno.
> Consequently, rc value is propagated to delete_depth_big() ->
> rte_lpm_delete(), and on failure the latter returns "1" value, which conflicts
> with the LPM API:
> "0 on success, negative value otherwise"
> I would suggest here to return -rte_errno if rc is equal to 1.
>
Yes, the return value is a little different from LPM APIs.
Will change it in next version to keep consistent with other LPM APIs.
Thanks.
/Ruifeng
>
> > + if (rc != 0)
> > + RTE_LOG(ERR, LPM, "Failed to push QSBR FIFO\n");
> > }
> > +
> > + return rc;
> > }
> >
> > static __rte_noinline int32_t
> > @@ -1041,6 +1046,7 @@ delete_depth_big(struct rte_lpm *lpm, uint32_t
> ip_masked,
> > uint32_t tbl24_index, tbl8_group_index, tbl8_group_start,
> tbl8_index,
> > tbl8_range, i;
> > int32_t tbl8_recycle_index;
> > + int rc = 0;
> >
> > /*
> > * Calculate the index into tbl24 and range. Note: All depths
> > larger @@ -1097,7 +1103,7 @@ delete_depth_big(struct rte_lpm *lpm,
> uint32_t ip_masked,
> > */
> > lpm->tbl24[tbl24_index].valid = 0;
> > __atomic_thread_fence(__ATOMIC_RELEASE);
> > - tbl8_free(lpm, tbl8_group_start);
> > + rc = tbl8_free(lpm, tbl8_group_start);
> > } else if (tbl8_recycle_index > -1) {
> > /* Update tbl24 entry. */
> > struct rte_lpm_tbl_entry new_tbl24_entry = { @@ -1113,10
> +1119,10
> > @@ delete_depth_big(struct rte_lpm *lpm, uint32_t ip_masked,
> > __atomic_store(&lpm->tbl24[tbl24_index],
> &new_tbl24_entry,
> > __ATOMIC_RELAXED);
> > __atomic_thread_fence(__ATOMIC_RELEASE);
> > - tbl8_free(lpm, tbl8_group_start);
> > + rc = tbl8_free(lpm, tbl8_group_start);
> > }
> > #undef group_idx
> > - return 0;
> > + return (int32_t)rc;
> > }
> >
> > /*
> >
>
> --
> Regards,
> Vladimir
