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Message-ID: <0242ccfe-53e5-5b9d-9fd9-73fa8bd0d7a4@huawei.com>
Date: Sat, 8 Oct 2022 13:16:42 +0800
From: wangyufen <wangyufen@...wei.com>
To: Quentin Monnet <quentin@...valent.com>, <ast@...nel.org>,
<daniel@...earbox.net>, <andrii@...nel.org>,
<martin.lau@...ux.dev>, <song@...nel.org>, <yhs@...com>,
<john.fastabend@...il.com>, <kpsingh@...nel.org>, <sdf@...gle.com>,
<haoluo@...gle.com>, <jolsa@...nel.org>, <davem@...emloft.net>,
<kuba@...nel.org>, <hawk@...nel.org>, <nathan@...nel.org>,
<ndesaulniers@...gle.com>, <trix@...hat.com>
CC: <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<netdev@...r.kernel.org>, <llvm@...ts.linux.dev>
Subject: Re: [bpf-next v7 1/3] bpftool: Add auto_attach for bpf prog
load|loadall
在 2022/10/1 0:26, Quentin Monnet 写道:
> Tue Sep 27 2022 12:21:14 GMT+0100 ~ Wang Yufen <wangyufen@...wei.com>
>> Add auto_attach optional to support one-step load-attach-pin_link.
> Nit: Now "autoattach" instead of "auto_attach". Same in commit title.
will change in v8, thanks.
>
>> For example,
>> $ bpftool prog loadall test.o /sys/fs/bpf/test autoattach
>>
>> $ bpftool link
>> 26: tracing name test1 tag f0da7d0058c00236 gpl
>> loaded_at 2022-09-09T21:39:49+0800 uid 0
>> xlated 88B jited 55B memlock 4096B map_ids 3
>> btf_id 55
>> 28: kprobe name test3 tag 002ef1bef0723833 gpl
>> loaded_at 2022-09-09T21:39:49+0800 uid 0
>> xlated 88B jited 56B memlock 4096B map_ids 3
>> btf_id 55
>> 57: tracepoint name oncpu tag 7aa55dfbdcb78941 gpl
>> loaded_at 2022-09-09T21:41:32+0800 uid 0
>> xlated 456B jited 265B memlock 4096B map_ids 17,13,14,15
>> btf_id 82
>>
>> $ bpftool link
>> 1: tracing prog 26
>> prog_type tracing attach_type trace_fentry
>> 3: perf_event prog 28
>> 10: perf_event prog 57
>>
>> The autoattach optional can support tracepoints, k(ret)probes,
>> u(ret)probes.
>>
>> Signed-off-by: Wei Yongjun <weiyongjun1@...wei.com>
>> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
>> ---
>> v6 -> v7: add info msg print and update doc for the skip program
>> v5 -> v6: skip the programs not supporting auto-attach,
>> and change optional name from "auto_attach" to "autoattach"
>> v4 -> v5: some formatting nits of doc
>> v3 -> v4: rename functions, update doc, bash and do_help()
>> v2 -> v3: switch to extend prog load command instead of extend perf
>> v2: https://patchwork.kernel.org/project/netdevbpf/patch/20220824033837.458197-1-weiyongjun1@huawei.com/
>> v1: https://patchwork.kernel.org/project/netdevbpf/patch/20220816151725.153343-1-weiyongjun1@huawei.com/
>> tools/bpf/bpftool/prog.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 79 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
>> index c81362a..84eced8 100644
>> --- a/tools/bpf/bpftool/prog.c
>> +++ b/tools/bpf/bpftool/prog.c
>> @@ -1453,6 +1453,72 @@ static int do_run(int argc, char **argv)
>> return ret;
>> }
>>
>> +static int
>> +auto_attach_program(struct bpf_program *prog, const char *path)
>> +{
>> + struct bpf_link *link;
>> + int err;
>> +
>> + link = bpf_program__attach(prog);
>> + if (!link)
>> + return -1;
>> +
>> + err = bpf_link__pin(link, path);
>> + if (err) {
>> + bpf_link__destroy(link);
>> + return err;
>> + }
>> + return 0;
>> +}
>> +
>> +static int pathname_concat(const char *path, const char *name, char *buf)
>> +{
>> + int len;
>> +
>> + len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
>> + if (len < 0)
>> + return -EINVAL;
>> + if (len >= PATH_MAX)
>> + return -ENAMETOOLONG;
>> +
>> + return 0;
>> +}
>> +
>> +static int
>> +auto_attach_programs(struct bpf_object *obj, const char *path)
>> +{
>> + struct bpf_program *prog;
>> + char buf[PATH_MAX];
>> + int err;
>> +
>> + bpf_object__for_each_program(prog, obj) {
>> + err = pathname_concat(path, bpf_program__name(prog), buf);
>> + if (err)
>> + goto err_unpin_programs;
>> +
>> + err = auto_attach_program(prog, buf);
>> + if (!err)
>> + continue;
>> + if (errno == EOPNOTSUPP)
>> + p_info("Program %s does not support autoattach",
>> + bpf_program__name(prog));
>> + else
>> + goto err_unpin_programs
> With this code, if auto-attach fails, then we skip this program and move
> on to the next. That's an improvement, but in that case the program
> won't remain loaded in the kernel after bpftool exits. My suggestion in
> my previous message (sorry if it was not clear) was to fall back to
> regular pinning in that case (bpf_obj_pin()), along with the p_info()
> message, so we can have the program pinned but not attached and let the
> user know. If regular pinning fails as well, then we should unpin all
> and error out, for consistency with bpf_object__pin_programs().
>
> And in that case, the (errno == EOPNOTSUPP) with fallback to regular
> pinning could maybe be moved into auto_attach_program(), so that
> auto-attaching single programs can use the fallback too?
>
> Thanks,
> Quentin
If I understand correctly, can we just check link? as following:
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1460,9 +1460,10 @@ static int do_run(int argc, char **argv)
int err;
link = bpf_program__attach(prog);
- if (!link)
- return -1;
-
+ if (!link) {
+ p_info("Program %s attach failed", bpf_program__name(prog));
+ return bpf_obj_pin(bpf_program__fd(prog), path);
+ }
err = bpf_link__pin(link, path);
if (err) {
bpf_link__destroy(link);
@@ -1499,9 +1500,6 @@ static int pathname_concat(const char *path, const char *name, char *buf)
err = auto_attach_program(prog, buf);
if (!err)
continue;
- if (errno == EOPNOTSUPP)
- p_info("Program %s does not support autoattach",
- bpf_program__name(prog));
else
goto err_unpin_programs;
}
and the doc is modified as follows:
If the program does not support autoattach, will do regular pin along with an
info message such as "Program %s attach failed". If the *OBJ* contains multiple
programs and **loadall** is used, if the program A in these programs does not
support autoattach, the program A will do regular pin along with an info message,
and continue to autoattach the next program.
Thanks,
Wang
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