netdev - Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support for BPF_PROG_TYPE_PERF

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Message-ID: <20160901163722.GY10153@twins.programming.kicks-ass.net>
Date:   Thu, 1 Sep 2016 18:37:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Alexei Starovoitov <ast@...com>,
        "David S . Miller" <davem@...emloft.net>,
        Brendan Gregg <bgregg@...flix.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Arnaldo Carvalho de Melo <acme@...radead.org>,
        Wang Nan <wangnan0@...wei.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH v2 net-next 4/6] perf, bpf: add perf events core support
 for BPF_PROG_TYPE_PERF_EVENT programs

On Thu, Sep 01, 2016 at 08:53:51AM -0700, Alexei Starovoitov wrote:
> On Thu, Sep 01, 2016 at 10:12:51AM +0200, Peter Zijlstra wrote:

> > Please, no leading space before labels. Use something like:
> 
> good catch.
> sadly checkpatch didn't complain.

Right, a lot of people do it on purpose to avoid diff seeing the label
as the function for --show-c-function. I just find the style annoying
and 'fixed' diff.

Now, if the option would've been called --show-function (without the
explicit reference to C) one could argue that seeing this form is useful
for .S files but... ;-)

> > [diff "default"]
> >         xfuncname = "^[[:alpha:]$_].*[^:]$"
> > 
> > In your .gitconfig if you want to keep diff output 'sane'.
> 
> interesting trick. don't remember being bitten by it.
> This extra space was a typo.

Example below, see the difference in the @@ line. I find the first
(fixed) to be much more useful.

With:

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8b3ad4e26548..cc2af0188924 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6238,6 +6238,7 @@ static void perf_pmu_output_stop(struct perf_event *event)
 			goto restart;
 		}
 	}
+	/* ponies */
 	rcu_read_unlock();
 }
 


Without:

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8b3ad4e26548..cc2af0188924 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6238,6 +6238,7 @@ restart:
 			goto restart;
 		}
 	}
+	/* ponies */
 	rcu_read_unlock();
 }