From: Ferruh Yigit <ferruh.yigit@intel.com> To: Kevin Traynor <ktraynor@redhat.com>, dev@dpdk.org Cc: stable@dpdk.org, allain.legacy@windriver.com, Steven Webster <steven.webster@windriver.com>, Matt Peters <matt.peters@windriver.com>, "Kilheeney, Louise" <louise.kilheeney@intel.com> Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v2 1/2] net/avp: fix gcc 10 maybe-uninitialized warning Date: Thu, 12 Mar 2020 16:47:49 +0000 Message-ID: <6abf293a-9007-c06f-c216-8d8331709b51@intel.com> (raw) In-Reply-To: <24e2ec05-de5d-3251-ac63-f344ec09f44e@redhat.com> On 3/12/2020 3:15 PM, Kevin Traynor wrote: > On 12/03/2020 14:31, Ferruh Yigit wrote: >> On 3/12/2020 2:18 PM, Kevin Traynor wrote: >>> On 12/03/2020 13:25, Ferruh Yigit wrote: >>>> On 3/11/2020 11:32 AM, Kevin Traynor wrote: >>>>> gcc 10.0.1 reports: >>>>> >>>>> ../drivers/net/avp/avp_ethdev.c: In function ‘avp_xmit_scattered_pkts’: >>>>> ../drivers/net/avp/avp_ethdev.c:1791:24: >>>>> warning: ‘avp_bufs[count]’ may be used uninitialized in this function [-Wmaybe-uninitialized] >>>>> 1791 | tx_bufs[i] = avp_bufs[count]; >>>>> | ~~~~~~~~^~~~~~~ >>>>> ../drivers/net/avp/avp_ethdev.c:1791:24: >>>>> warning: ‘avp_bufs[count]’ may be used uninitialized in this function [-Wmaybe-uninitialized] >>>>> >>>>> Fix by intializing the array. >>>>> >>>>> Fixes: 295abce2d25b ("net/avp: add packet transmit functions") >>>>> Cc: stable@dpdk.org >>>>> >>>>> Signed-off-by: Kevin Traynor <ktraynor@redhat.com> >>>>> --- >>>>> v2: no change >>>>> >>>>> note, commit log violates line length but I didn't want to split warning msg. >>>>> >>>>> Cc: allain.legacy@windriver.com >>>>> Cc: Steven Webster <steven.webster@windriver.com> >>>>> Cc: Matt Peters <matt.peters@windriver.com> >>>>> --- >>>>> drivers/net/avp/avp_ethdev.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/net/avp/avp_ethdev.c b/drivers/net/avp/avp_ethdev.c >>>>> index cd747b6be..1abe96ce5 100644 >>>>> --- a/drivers/net/avp/avp_ethdev.c >>>>> +++ b/drivers/net/avp/avp_ethdev.c >>>>> @@ -1695,5 +1695,5 @@ avp_xmit_scattered_pkts(void *tx_queue, >>>>> { >>>>> struct rte_avp_desc *avp_bufs[(AVP_MAX_TX_BURST * >>>>> - RTE_AVP_MAX_MBUF_SEGMENTS)]; >>>>> + RTE_AVP_MAX_MBUF_SEGMENTS)] = {}; >>>>> struct avp_queue *txq = (struct avp_queue *)tx_queue; >>>>> struct rte_avp_desc *tx_bufs[AVP_MAX_TX_BURST]; >>>>> >>>> >>>> Isn't this a false positive, can there be any case 'avp_bufs[]' used >>>> uninitialized? Or am I missing something. >>>> >>> >>> I presume it's because it's not being initialized in the fn and there is >>> some paths in fn's it's passed to that don't initialize it. Of course in >>> practice with "normal" values this might not happen. >> >> 'avp_fifo_get(alloc_q, (void **)&avp_bufs, segments);' initializes it, and I am >> not just talking about 'normal' case, I don't see any case that 'avp_bufs[]' >> used uninitialized, can you see any? >> > > Well, it's initialization there is dependent on not hitting the first > return and the loop executing. If whole array not initialized, the next line, 'if (unlikely(n != segments))', will catch it and function return without using 'avp_bufs[]' at all. Anyway, as I said I can't see a case that 'avp_bufs[]' used uninitialized, and not sure about additional zeroing out in datapath function if this is a false positive, but if windriver guys are OK I won't object. > >>> >>>> If this is false positive, does it worth to report to issue to gcc? >>>> >>> >> >
prev parent reply other threads:[~2020-03-12 16:47 UTC|newest] Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-20 9:37 [dpdk-stable] [PATCH " Kevin Traynor 2020-02-20 9:37 ` [dpdk-stable] [PATCH 2/2] examples/ipsec-gw: " Kevin Traynor 2020-02-26 6:12 ` Akhil Goyal 2020-03-10 13:08 ` Ananyev, Konstantin 2020-03-10 18:52 ` Kevin Traynor 2020-03-10 19:03 ` Ananyev, Konstantin 2020-03-11 11:32 ` [dpdk-stable] [PATCH v2 1/2] net/avp: " Kevin Traynor 2020-03-11 11:33 ` [dpdk-stable] [PATCH v2 2/2] examples/ipsec-gw: " Kevin Traynor 2020-03-11 12:04 ` Ananyev, Konstantin 2020-05-06 9:18 ` [dpdk-stable] [dpdk-dev] " David Marchand 2020-03-11 23:56 ` [dpdk-stable] [PATCH v2 1/2] net/avp: " Webster, Steven 2020-05-06 9:18 ` David Marchand 2020-03-12 13:25 ` [dpdk-stable] [dpdk-dev] " Ferruh Yigit 2020-03-12 14:18 ` Kevin Traynor 2020-03-12 14:31 ` Ferruh Yigit 2020-03-12 15:15 ` Kevin Traynor 2020-03-12 16:47 ` Ferruh Yigit [this message]
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