> -----Original Message----- > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Azarewicz, PiotrX T > Sent: Thursday, May 12, 2016 1:20 PM > To: Mrozowicz, SlawomirX <slawomirx.mrozowicz at intel.com>; Richardson, > Bruce <bruce.richardson at intel.com> > Cc: dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH] lpm: unchecked return value > > Hi, > > I handle Coverity defect ID 13201. It is about unchecked return value from > rte_lpm6_delete() instances in rte_lpm6_add() function. > Next I found this thread and I see that both defects (ID 13205 and ID 13201) > may be resolved all together. > > > >> Fix issue reported by Coverity. > > >> > > >> Coverity ID 13205: Unchecked return value Unchecked return value > > >> check_return: Calling rte_lpm6_add without checking return value > > >> Fixes: 5c510e13a9cb ("lpm: add IPv6 support") > > >> > > >> Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz at intel.com> > > >> --- > > >> lib/librte_lpm/rte_lpm6.c | 10 ++++++---- > > >> 1 file changed, 6 insertions(+), 4 deletions(-) > > >> > > >> diff --git a/lib/librte_lpm/rte_lpm6.c b/lib/librte_lpm/rte_lpm6.c > > >> index ba4353c..f4db3fa 100644 > > >> --- a/lib/librte_lpm/rte_lpm6.c > > >> +++ b/lib/librte_lpm/rte_lpm6.c > > >> @@ -749,6 +749,7 @@ rte_lpm6_delete(struct rte_lpm6 *lpm, uint8_t > > >> *ip, > > >uint8_t depth) > > >> int32_t rule_to_delete_index; > > >> uint8_t ip_masked[RTE_LPM6_IPV6_ADDR_SIZE]; > > >> unsigned i; > > >> + int status = 0; > > >> > > >> /* > > >> * Check input arguments. > > >> @@ -790,12 +791,13 @@ rte_lpm6_delete(struct rte_lpm6 *lpm, > uint8_t > > >*ip, uint8_t depth) > > >> * Add every rule again (except for the one that was removed > > >> from > > >> * the rules table). > > >> */ > > >> - for (i = 0; i < lpm->used_rules; i++) { > > >> - rte_lpm6_add(lpm, lpm->rules_tbl[i].ip, lpm- > > >>rules_tbl[i].depth, > > >> - lpm->rules_tbl[i].next_hop); > > >> + for (i = 0; i < lpm->used_rules && status >= 0; i++) { > > >> + status = rte_lpm6_add( > > >> + lpm, lpm->rules_tbl[i].ip, > > >> lpm->rules_tbl[i].depth, > > >> + lpm->rules_tbl[i].next_hop); > > >> } > > >> > > >> - return 0; > > >> + return status; > > >> } > > > > > >Hi, > > > > > >I'm not sure that this patch is actually necessary, as I'm not sure > > >that the lpm6_add calls can fail in this instance. Looking through the > > >code, this function deletes the rule and then clears the actual lpm > > >lookup tables before re-adding all other routes to it again. The only > > >error condition that could be returned, that I can see, is -ENOSPC, > > >which should never occur here since the original rules fitted in the first > > place. > > I agree that -ENOSPC should never occur here. So rte_lpm6_add() instance > should never fail here. > > Next I looked at rte_lpm6_add() and if rte_lpm6_delete() instances in it > may fail? > The only suspicious place that I found is place when add every rule again > but that should work as discussed above. > > > > > > >If it was possible to fail, then I think we would have a worse problem, > > >in that deleting a single rule has wiped out our lpm table and left it > > >in an inconsistent state, so the error handling probably needs to be > better > > than just quitting. > > > > > >Finally, one other thing I spot looking through the code, is that there > > >seems to be a worrying set of calls between add and delete. If the add > > >function fails, then it calls delete which in turn will call add again, > > >etc. etc. This may all work correctly, but it seems fragile and error > > >prone to me - especially if we allow calls from one to another to fail. > > > > > >This looks like it might need some further examination to verify what > > >the possible failure cases are and what happens in each scenario. > > I see no failure scenarios in here. I mean I see no possibility to create test > that show that add function fail in del and opposite. > The only scenario what I have in my mind is that someone call add or/and > del functions on different threads with the same lpm table instance, but > this is not allowed, cause we know that this functions are not thread safe. > > > > > > >Regards, > > >/Bruce > > > > > > Hi Bruce, > > > > In my opinion the worst-case scenario should be take into account. If > > function like rte_lpm6_add() returns false then it should be handled. > > > > Anyway I agree with you that if the function fail then we have serious > > problem. > > I see two problems: > > 1. Code construction: calls between function rte_lpm6_add() and > > rte_lpm6_delete(). As you said it should be examined. > > 2. How we should handle situation if the rules table are not reconstructed > > after delete operation. > > > > I propose to add new issue in ClearQuest to proceed solve the problems > > because there are extend the original issue (CID 13205 Unchecked return > > value) from Coverity. > > > > Regards, > > S?awomir > > I propose to classify this Coverity issues (ID 13205 and ID 13201) as > Intentional. > > Regards, > Piotr
Hi Bruce, We would like to move forward with theses Coverity defects thus Please share your opinion about classifying these defects as Intentional? Michal
