From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Alexei Starovoitov <ast@plumgrid.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
linux-api@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 linux-trace 4/8] samples: bpf: simple tracing example in C
Date: Wed, 28 Jan 2015 13:25:57 -0300 [thread overview]
Message-ID: <20150128162557.GP7220@kernel.org> (raw)
In-Reply-To: <20150128162415.GO7220@kernel.org>
Em Wed, Jan 28, 2015 at 01:24:15PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Tue, Jan 27, 2015 at 08:06:09PM -0800, Alexei Starovoitov escreveu:
> > diff --git a/samples/bpf/tracex1_kern.c b/samples/bpf/tracex1_kern.c
> > new file mode 100644
> > index 000000000000..7849ceb4bce6
> > --- /dev/null
> > +++ b/samples/bpf/tracex1_kern.c
> > @@ -0,0 +1,28 @@
> > +#include <linux/skbuff.h>
> > +#include <linux/netdevice.h>
> > +#include <uapi/linux/bpf.h>
> > +#include <trace/bpf_trace.h>
> > +#include "bpf_helpers.h"
> > +
> > +SEC("events/net/netif_receive_skb")
> > +int bpf_prog1(struct bpf_context *ctx)
> > +{
> > + /*
> > + * attaches to /sys/kernel/debug/tracing/events/net/netif_receive_skb
> > + * prints events for loobpack device only
> > + */
> > + char devname[] = "lo";
> > + struct net_device *dev;
> > + struct sk_buff *skb = 0;
> > +
> > + skb = (struct sk_buff *) ctx->arg1;
> > + dev = bpf_fetch_ptr(&skb->dev);
> > + if (bpf_memcmp(dev->name, devname, 2) == 0)
>
> I'm only starting to look at all this, so bear with me... But why do we
> need to have it as "bpf_memcmp"? Can't we simply use it as "memcmp" and
> have it use the right function?
>
> Less typing, perhaps we would need to have a:
>
> #define memcmp bpf_memcmp(s1, s2, n) bpf_memcmp(s1, s2, n)
Argh, like this:
#define memcmp(s1, s2, n) bpf_memcmp(s1, s2, n)
> in bpf_helpers.h to have it work?
>
> - Arnaldo
>
> > + /* print event using default tracepoint format */
> > + return 1;
> > +
> > + /* drop event */
> > + return 0;
> > +}
next prev parent reply other threads:[~2015-01-29 1:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-28 4:06 [PATCH v2 linux-trace 0/8] tracing: attach eBPF programs to tracepoints/syscalls/kprobe Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 1/8] tracing: attach eBPF programs to tracepoints and syscalls Alexei Starovoitov
2015-01-29 0:46 ` Namhyung Kim
2015-01-28 4:06 ` [PATCH v2 linux-trace 2/8] tracing: allow eBPF programs to call ktime_get_ns() Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 3/8] samples: bpf: simple tracing example in eBPF assembler Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 4/8] samples: bpf: simple tracing example in C Alexei Starovoitov
2015-01-28 16:24 ` Arnaldo Carvalho de Melo
2015-01-28 16:25 ` Arnaldo Carvalho de Melo [this message]
2015-01-28 16:42 ` Alexei Starovoitov
2015-01-28 20:44 ` Arnaldo Carvalho de Melo
2015-01-28 4:06 ` [PATCH v2 linux-trace 5/8] samples: bpf: counting example for kfree_skb tracepoint and write syscall Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 6/8] samples: bpf: IO latency analysis (iosnoop/heatmap) Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 7/8] tracing: attach eBPF programs to kprobe/kretprobe Alexei Starovoitov
2015-01-28 4:06 ` [PATCH v2 linux-trace 8/8] samples: bpf: simple kprobe example Alexei Starovoitov
2015-01-29 4:19 [PATCH v2 linux-trace 4/8] samples: bpf: simple tracing example in C Alexei Starovoitov
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