Re: [dpdk-dev] [PATCH] eal: fix API to get error string

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Fri, 2 Nov 2018 15:39:04 +0000
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> CC: Bruce Richardson <bruce.richardson@intel.com>, "dev@dpdk.org"
>  <dev@dpdk.org>, "stable@dpdk.org" <stable@dpdk.org>
> Subject: Re: [dpdk-dev] [PATCH] eal: fix API to get error string
> User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101
>  Thunderbird/52.9.1
> 
> 
> On 11/2/2018 9:51 AM, Jerin Jacob wrote:
> > -----Original Message-----
> >> Date: Wed, 31 Oct 2018 17:19:28 +0000
> >> From: Ferruh Yigit <ferruh.yigit@intel.com>
> >> To: Bruce Richardson <bruce.richardson@intel.com>
> >> CC: dev@dpdk.org, Ferruh Yigit <ferruh.yigit@intel.com>, stable@dpdk.org
> >> Subject: [dpdk-dev] [PATCH] eal: fix API to get error string
> >> X-Mailer: git-send-email 2.17.2
> >>
> >> External Email
> >>
> >> rte_strerror uses strerror_r(), and strerror_r() has two version of it.
> >> - XSI-compliant version, (_POSIX_C_SOURCE >= 200112L) && !  _GNU_SOURCE
> >> - GNU-specific version
> >>
> >> Those two has different return types, so the exiting return type check
> >> is not correct for GNU-specific version.
> >>
> >> And this is causing failure in errno_autotest unit test.
> >>
> >> Adding different implementation for FreeBSD and Linux.
> >>
> >> Fixes: 016c32bd3e3d ("eal: cleanup strerror function")
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> >> ---
> >>  lib/librte_eal/common/eal_common_errno.c | 8 ++++++++
> >>  1 file changed, 8 insertions(+)
> >>
> >> diff --git a/lib/librte_eal/common/eal_common_errno.c b/lib/librte_eal/common/eal_common_errno.c
> >> index 56b492f5f..fbbc71b0b 100644
> >> --- a/lib/librte_eal/common/eal_common_errno.c
> >> +++ b/lib/librte_eal/common/eal_common_errno.c
> >> @@ -38,9 +38,17 @@ rte_strerror(int errnum)
> >>                 case E_RTE_NO_CONFIG:
> >>                         return "Missing rte_config structure";
> >>                 default:
> >> +#ifdef RTE_EXEC_ENV_BSDAPP
> >>                         if (strerror_r(errnum, ret, RETVAL_SZ) != 0)
> >>                                 snprintf(ret, RETVAL_SZ, "Unknown error%s %d",
> >>                                                 sep, errnum);
> >> +#else
> >> +                       /*
> >> +                        * _GNU_SOURCE version, error string is not always
> >> +                        * strored in "ret" buffer, need to use return value
> >> +                        */
> >> +                       ret = strerror_r(errnum, ret, RETVAL_SZ);
> >
> > Probably this will fail in musl c version.
> > https://git.musl-libc.org/cgit/musl/tree/src/string/strerror_r.c
> 
> You are right, it will fail with musl. It may not be good idea to separate this
> as BSD and Linux.
> 
> Instead of playing with strerror_r(), what about use strerror() and copy string
> to RTE_PER_LCORE(retval)? I will send a patch for it.

I thought we used strerror_r() to enable thread safety.IMO, strerror()
is not thread safe.

> 
> >
> > Another alternative of this patch.
> >
> > http://patches.dpdk.org/patch/47706/
> 
> I think this works, but I am not sure if it will have any side effect. And if we
> want to add more functions to this file, that may be effected. I am more to fix
> this locally in rte_strerror() function.

If we can then it is good.

> 
> >
> >> +#endif
> >>                 }
> >>
> >>         return ret;
> >> --
> >> 2.17.2
> >>
>