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From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
	Denton Liu <liu.denton@gmail.com>,
	Jeff Hostetler <jeffhost@microsoft.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH v3] trace2: refactor to avoid gcc warning under -O3
Date: Thu, 20 May 2021 09:13:09 -0400	[thread overview]
Message-ID: <YKZgZZrZdKyUk9d9@coredump.intra.peff.net> (raw)
In-Reply-To: <patch-1.1-2e41e3e4cb-20210520T110357Z-avarab@gmail.com>

On Thu, May 20, 2021 at 01:05:45PM +0200, Ævar Arnfjörð Bjarmason wrote:

> >> I also wondered briefly why we needed the out-parameter at all, and not
> >> just letting the caller look at errno. The answer is that we need to
> >> preserve it across the close() call. The more usual thing in our code
> >> base would be to use saved_errno, but not have it as an out-parameter.
> >> [...]
> > I think this alternative is more readable as well.
> >
> > I'll mark the topic to be "Expecting a reroll" in the what's cooking
> > report.
> >
> > Thanks.
> 
> Here's that re-roll, thanks both.

Thanks, this looks OK to me. There is one minor nit (introduced by me!)
below, but I'm not sure if we should care or not.

> The patch is entirely Jeff's at this point (from
> <YJrIMbr6VkYGQMfs@coredump.intra.peff.net>), with my amended commit
> message. So I added his SOB per his recent-ish ML "every patch of mine
> can be assumed to have my SOB" message.

So I have definitely said that, and I stand by it. But as a matter of
project policy, I think we probably shouldn't consider that "enough".
The point of the DSO is to make an affirmative statement about a
particular patch. So probably my blanket statement should be taken more
as "I will almost definitely add my signoff if you ask me". :)

And of course in the case of this particular patch, it is very much:

  Signed-off-by: Jeff King <peff@peff.net>

> @@ -271,15 +271,13 @@ static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,
>  	}
>  
>  	if (uds_try & TR2_DST_UDS_TRY_STREAM) {
> -		e = tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd);
> -		if (!e)
> +		if (!tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd))
>  			goto connected;
> -		if (e != EPROTOTYPE)
> +		if (errno != EPROTOTYPE)
>  			goto error;
>  	}
>  	if (uds_try & TR2_DST_UDS_TRY_DGRAM) {
> -		e = tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd);
> -		if (!e)
> +		if (!tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd))
>  			goto connected;
>  	}
>  
> @@ -287,7 +285,7 @@ static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,
>  	if (tr2_dst_want_warning())
>  		warning("trace2: could not connect to socket '%s' for '%s' tracing: %s",
>  			path, tr2_sysenv_display_name(dst->sysenv_var),
> -			strerror(e));
> +			strerror(errno));

We expect the value of errno to persist across tr2_dst_want_warning()
and tr2_sysenv_display_name() here. The former may call getenv() and
atoi(). I think that's probably fine, but if we wanted to be really
paranoid, we'd have to preserve errno manually here, too.

-Peff

  reply	other threads:[~2021-05-20 13:13 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-01  7:30 [PATCH] Fix -Wmaybe-uninitialized warnings under -O0 Denton Liu
     [not found] ` <CAPUEspgBkmxszgBee8C9hZnEwqztf-XKEj7LB_jWVFJaJCge0w@mail.gmail.com>
2020-04-01  9:05   ` Denton Liu
2020-04-01  9:52 ` Jeff King
2020-04-01 14:06   ` Denton Liu
2020-04-03 14:04     ` Jeff King
2020-04-03 14:38       ` Jeff King
2020-04-04 12:07       ` Denton Liu
2020-04-04 14:21         ` Jeff King
2021-05-05  8:40           ` [PATCH] trace2: refactor to avoid gcc warning under -O3 Ævar Arnfjörð Bjarmason
2021-05-05  9:47             ` Junio C Hamano
2021-05-05 13:34               ` Jeff King
2021-05-05 14:38             ` Johannes Schindelin
2021-05-06  1:26               ` Junio C Hamano
2021-05-06 20:29                 ` Johannes Schindelin
2021-05-06 21:10                   ` Junio C Hamano
2021-05-11 14:34                     ` Johannes Schindelin
2021-05-11 18:00                       ` Jeff King
2021-05-11 20:58                         ` Junio C Hamano
2021-05-11 21:07                           ` Jeff King
2021-05-11 21:33                             ` Junio C Hamano
2021-05-11  7:03             ` Junio C Hamano
2021-05-11 13:04             ` [PATCH v2] " Ævar Arnfjörð Bjarmason
2021-05-11 16:40               ` Jeff Hostetler
2021-05-11 17:54               ` Jeff King
2021-05-11 18:08                 ` Jeff King
2021-05-11 21:09                   ` Junio C Hamano
2021-05-20  0:20                   ` Junio C Hamano
2021-05-20 11:05                     ` [PATCH v3] " Ævar Arnfjörð Bjarmason
2021-05-20 13:13                       ` Jeff King [this message]
2021-05-20 22:08                         ` Junio C Hamano
2021-05-21  9:34                           ` Jeff King

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