From: Bruce Richardson <bruce.richardson@intel.com>
To: Thomas Monjalon <thomas@monjalon.net>
Cc: dev@dpdk.org, Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [dpdk-dev] [PATCH 01/10] mk: adjust gcc flags for new gcc 7 warnings
Date: Fri, 5 May 2017 11:20:11 +0100 [thread overview]
Message-ID: <20170505102011.GA41052@bricha3-MOBL3.ger.corp.intel.com> (raw)
In-Reply-To: <1947779.Ji6X4lE9fr@xps>
On Fri, May 05, 2017 at 12:02:44PM +0200, Thomas Monjalon wrote:
> In this series, there are some fixes for fall-through comments,
> missing break and missing initializers.
> I think there is no discussion about accepting them in 17.05.
> The last item to discuss it the new snprintf warning:
>
> 05/05/2017 11:42, Bruce Richardson:
> > On Thu, May 04, 2017 at 09:38:08AM -0700, Stephen Hemminger wrote:
> > > On Thu, 4 May 2017 16:38:13 +0100
> > > Bruce Richardson <bruce.richardson@intel.com> wrote:
> > > > 2. GCC also warns about an snprintf where there may be truncation and the
> > > > return value is not checked. Given that we often use snprintf in DPDK in
> > > > place of strncpy, and in many cases where truncation is not a problem, we
> > > > can just disable this particular warning.
> [...]
> > > > --- a/mk/toolchain/gcc/rte.vars.mk
> > > > +++ b/mk/toolchain/gcc/rte.vars.mk
> > > > +# Ignore errors for snprintf truncation
> > > > +WERROR_FLAGS += -Wno-format-truncation
> [...]
> > 2. for the format truncation warning, ideally, yes we should fix the
> > code, except that I don't believe this is feasible in the short term,
> > and I also don't believe it is desirable. We extensively use snprintf
> > because it has sane/safe truncation, and in many cases we don't care if
> > it is being truncated. Therefore disabling the warning seems the best
> > approach to me. Furthermore, if we want 17.05 to compile with GCC 7,
> > this is the best option within that timeframe.
>
> We could imagine an explicit ignore of the return code.
> However, do we really want this new coding rule for every snprintf?
> It is a common call in DPDK:
> git grep '\<snprintf\>' | wc -l
> 774
> And probably almost never checked:
> git grep '^[[:space:]]*\<snprintf\>' | wc -l
> 660
>
> I suggest to disable this new warning in GCC 7.
> Any opinions?
I'd suggest that even fewer than that are actually recorded, let alone
checked:
git grep '= *snprintf\>' | wc -l
89
So I'm (obviously) +1 for dropping this warning check.
/Bruce
next prev parent reply other threads:[~2017-05-05 10:20 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-04 15:38 [dpdk-dev] [PATCH 00/10] Enable DPDK core build with gcc 7 Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 01/10] mk: adjust gcc flags for new gcc 7 warnings Bruce Richardson
2017-05-04 16:38 ` Stephen Hemminger
2017-05-05 9:42 ` Bruce Richardson
2017-05-05 10:02 ` Thomas Monjalon
2017-05-05 10:20 ` Bruce Richardson [this message]
2017-05-05 12:18 ` Van Haaren, Harry
2017-05-04 15:38 ` [dpdk-dev] [PATCH 02/10] drivers/net: disable new gcc 7 warnings for base code Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 03/10] net/bnx2x: fix warnings about switch fall-through Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 04/10] net/ixgbe: fix gcc 7 warning for switch fallthrough Bruce Richardson
2017-05-05 0:46 ` Lu, Wenzhuo
2017-05-04 15:38 ` [dpdk-dev] [PATCH 05/10] net/vmxnet3: fix compile error with gcc 7 Bruce Richardson
2017-05-04 16:39 ` Stephen Hemminger
2017-05-04 15:38 ` [dpdk-dev] [PATCH 06/10] lib: fix gcc 7 warnings for switch fall-through Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 07/10] net: fix missing break inside conditional compile block Bruce Richardson
2017-05-05 9:28 ` Singh, Jasvinder
2017-05-04 15:38 ` [dpdk-dev] [PATCH 08/10] app/testpmd: document explicit switch fall-through Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 09/10] test/test: fix missing break in switch Bruce Richardson
2017-05-04 15:38 ` [dpdk-dev] [PATCH 10/10] test/test: fix gcc 7 compiler error Bruce Richardson
2017-05-05 16:38 ` [dpdk-dev] [PATCH 00/10] Enable DPDK core build with gcc 7 Thomas Monjalon
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