From: Bruce Richardson <bruce.richardson@intel.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: Olivier Matz <olivier.matz@6wind.com>,
dev@dpdk.org, cristian.dumitrescu@intel.com
Subject: Re: [dpdk-dev] [PATCH 08/10] lpm6: fix compilation with -Og
Date: Thu, 26 Oct 2017 11:42:26 +0100 [thread overview]
Message-ID: <20171026104226.GA11456@bricha3-MOBL3.ger.corp.intel.com> (raw)
In-Reply-To: <228abb94-4939-8425-9451-2fb57fd1c567@intel.com>
On Fri, Oct 06, 2017 at 01:18:00AM +0100, Ferruh Yigit wrote:
> On 9/11/2017 4:13 PM, Olivier Matz wrote:
> > The compilation with gcc-6.3.0 and EXTRA_CFLAGS=-Og gives the following
> > error:
> >
> > CC rte_lpm6.o
> > rte_lpm6.c: In function ‘rte_lpm6_add_v1705’:
> > rte_lpm6.c:442:11: error: ‘tbl_next’ may be used uninitialized in
> > this function [-Werror=maybe-uninitialized]
> > if (!tbl[tbl_index].valid) {
> > ^
> > rte_lpm6.c:521:29: note: ‘tbl_next’ was declared here
> > struct rte_lpm6_tbl_entry *tbl_next;
> > ^~~~~~~~
> >
> > This is a false positive from gcc. Fix it by initializing tbl_next
> > to NULL.
>
> This is hard to trace, and it seems there is a way to have it, not sure
> practically possible:
>
> rte_lpm6_add_v1705
> add_step
> if (depth <= bits_covered) {
> ...
> return 0 <--- so tbl_next stays untouched.
> tbl = tbl_next
> add_step
> tbl[tbl_index]
>
>
> So same comment as previous, if there is a practically available path,
> this patch makes it harder to find by hiding compiler warning, so adding
> maintainer for decision.
>
>
+Cristian, who has more knowledge of this library than I.
I don't think there is an issue here, since there is an additional check
before the second and subsequent calls to add_step(). The condition
check on the loop in add_v1705 is:
"i < RTE_LPM6_IPV6_ADDR_SIZE && status == 1;"
The "return 0" sets status to 0, causing the loop to break, preventing
any more calls to "tbl = tbl_next".
Therefore I don't think this masks an issue, and the fix is ok.
In the absense of any other objections or comments on this from
Cristian:
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
next prev parent reply other threads:[~2017-10-26 10:42 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-11 15:13 [dpdk-dev] [PATCH 00/10] " Olivier Matz
2017-09-11 15:13 ` [dpdk-dev] [PATCH 01/10] net/bnxt: " Olivier Matz
2017-09-11 15:13 ` [dpdk-dev] [PATCH 02/10] net/qede: " Olivier Matz
2017-09-11 18:22 ` Patil, Harish
2017-09-11 15:13 ` [dpdk-dev] [PATCH 03/10] net/virtio: " Olivier Matz
2017-10-05 23:17 ` Ferruh Yigit
2017-10-05 23:28 ` Ferruh Yigit
2017-10-06 6:43 ` Maxime Coquelin
2017-10-06 18:43 ` Ferruh Yigit
2017-09-11 15:13 ` [dpdk-dev] [PATCH 04/10] net/i40e: " Olivier Matz
2017-10-05 23:24 ` Ferruh Yigit
2017-10-11 6:20 ` Wu, Jingjing
2017-10-11 7:52 ` Olivier MATZ
2017-09-11 15:13 ` [dpdk-dev] [PATCH 05/10] uio: " Olivier Matz
2017-09-11 15:13 ` [dpdk-dev] [PATCH 06/10] cmdline: " Olivier Matz
2017-09-11 15:13 ` [dpdk-dev] [PATCH 07/10] metrics: " Olivier Matz
2017-09-11 15:13 ` [dpdk-dev] [PATCH 08/10] lpm6: " Olivier Matz
2017-10-06 0:18 ` Ferruh Yigit
2017-10-26 10:42 ` Bruce Richardson [this message]
2017-10-26 18:54 ` Ferruh Yigit
2017-09-11 15:13 ` [dpdk-dev] [PATCH 09/10] app/test-crypto-perf: fix memory leak Olivier Matz
2017-10-05 9:29 ` De Lara Guarch, Pablo
2017-09-11 15:13 ` [dpdk-dev] [PATCH 10/10] app/test-crypto-perf: fix compilation with -Og Olivier Matz
2017-10-05 9:36 ` De Lara Guarch, Pablo
2017-09-11 15:28 ` [dpdk-dev] [PATCH 00/10] " Bruce Richardson
2017-10-06 0:26 ` Ferruh Yigit
2017-10-06 7:31 ` Olivier MATZ
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