From: Peter Zijlstra <peterz@infradead.org>
To: Alexei Starovoitov <ast@fb.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Wang Nan <wangnan0@huawei.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Brendan Gregg <brendan.d.gregg@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next 1/3] perf: generalize perf_callchain
Date: Thu, 25 Feb 2016 17:47:29 +0100 [thread overview]
Message-ID: <20160225164729.GS6356@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1455767939-2700534-2-git-send-email-ast@fb.com>
On Wed, Feb 17, 2016 at 07:58:57PM -0800, Alexei Starovoitov wrote:
> +static inline int perf_callchain_store(struct perf_callchain_entry *entry, u64 ip)
> {
> + if (entry->nr < PERF_MAX_STACK_DEPTH) {
> entry->ip[entry->nr++] = ip;
> + return 0;
> + } else {
> + return -1; /* no more room, stop walking the stack */
> + }
> }
Why 0 and -1 ?
What's wrong with something like:
static inline bool perf_callchain_store(struct perf_callchain_entry *entry, u64 ip)
{
if (entry->nr < PERF_MAX_STACK_DEPTH) {
entry->ip[entry->nr++] = ip;
return true;
}
return false;
}
next prev parent reply other threads:[~2016-02-25 16:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 3:58 [PATCH net-next 0/3] bpf_get_stackid() and stack_trace map Alexei Starovoitov
2016-02-18 3:58 ` [PATCH net-next 1/3] perf: generalize perf_callchain Alexei Starovoitov
2016-02-25 14:18 ` Peter Zijlstra
2016-02-25 16:37 ` Alexei Starovoitov
2016-02-25 16:45 ` Peter Zijlstra
2016-02-25 16:48 ` Peter Zijlstra
2016-02-25 16:47 ` Peter Zijlstra [this message]
2016-02-25 17:27 ` Alexei Starovoitov
2016-02-18 3:58 ` [PATCH net-next 2/3] bpf: introduce BPF_MAP_TYPE_STACK_TRACE Alexei Starovoitov
2016-02-25 14:23 ` Peter Zijlstra
2016-02-25 16:42 ` Alexei Starovoitov
2016-02-25 16:50 ` Peter Zijlstra
2016-02-18 3:58 ` [PATCH net-next 3/3] samples/bpf: offwaketime example Alexei Starovoitov
2016-02-20 5:25 ` [PATCH net-next 0/3] bpf_get_stackid() and stack_trace map David Miller
2016-02-25 14:24 ` Peter Zijlstra
2016-02-25 16:44 ` David Miller
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