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From: Jiri Olsa <jolsa@redhat.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andriin@fb.com>,
	Wenbo Zhang <ethercflow@gmail.com>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	Martin KaFai Lau <kafai@fb.com>, David Miller <davem@redhat.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@chromium.org>,
	Brendan Gregg <bgregg@netflix.com>,
	Florent Revest <revest@chromium.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v9 bpf-next 13/14] selftests/bpf: Add test for d_path helper
Date: Wed, 5 Aug 2020 20:00:34 +0200
Message-ID: <20200805180034.GE319954@krava> (raw)
In-Reply-To: <CAEf4BzYq5jhTPZRiRzDmi_92qg+0vwobmkyLEqB50mrG_39BeQ@mail.gmail.com>

On Tue, Aug 04, 2020 at 11:40:05PM -0700, Andrii Nakryiko wrote:

SNIP

> > +SEC("fentry/vfs_getattr")
> > +int BPF_PROG(prog_stat, struct path *path, struct kstat *stat,
> > +            __u32 request_mask, unsigned int query_flags)
> > +{
> > +       pid_t pid = bpf_get_current_pid_tgid() >> 32;
> > +       int ret;
> > +
> > +       if (pid != my_pid)
> > +               return 0;
> > +
> > +       if (cnt_stat >= MAX_FILES)
> > +               return 0;
> > +       ret = bpf_d_path(path, paths_stat[cnt_stat], MAX_PATH_LEN);
> > +
> > +       /* We need to recheck cnt_stat for verifier. */
> > +       if (cnt_stat >= MAX_FILES)
> > +               return 0;
> > +       rets_stat[cnt_stat] = ret;
> > +
> > +       cnt_stat++;
> > +       return 0;
> > +}
> > +
> > +SEC("fentry/filp_close")
> > +int BPF_PROG(prog_close, struct file *file, void *id)
> > +{
> > +       pid_t pid = bpf_get_current_pid_tgid() >> 32;
> > +       int ret;
> > +
> > +       if (pid != my_pid)
> > +               return 0;
> > +
> > +       if (cnt_close >= MAX_FILES)
> > +               return 0;
> > +       ret = bpf_d_path(&file->f_path,
> > +                        paths_close[cnt_close], MAX_PATH_LEN);
> > +
> > +       /* We need to recheck cnt_stat for verifier. */
> 
> you need to do it because you are re-reading a global variable; if you
> stored cnt_close in a local variable, then did >= MAX_FILES check
> once, you probably could have avoided this duplication. Same for
> another instance above.

I see, nice.. I'll update both comments

thanks,
jirka


  reply index

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01 17:03 [PATCH v9 bpf-next 00/14] bpf: Add " Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 01/14] tools resolve_btfids: Add size check to get_id function Jiri Olsa
2020-08-05  6:00   ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 02/14] tools resolve_btfids: Add support for set symbols Jiri Olsa
2020-08-05  6:04   ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 03/14] bpf: Move btf_resolve_size into __btf_resolve_size Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 04/14] bpf: Add elem_id pointer as argument to __btf_resolve_size Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 05/14] bpf: Add type_id " Jiri Olsa
2020-08-05  6:05   ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 06/14] bpf: Remove recursion call in btf_struct_access Jiri Olsa
2020-08-05  6:12   ` Andrii Nakryiko
2020-08-05 17:36     ` Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 07/14] bpf: Factor btf_struct_access function Jiri Olsa
2020-08-05  6:18   ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 08/14] bpf: Add btf_struct_ids_match function Jiri Olsa
2020-08-05  6:27   ` Andrii Nakryiko
2020-08-05 17:56     ` Jiri Olsa
2020-08-05 21:31       ` Jiri Olsa
2020-08-05 21:57         ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 09/14] bpf: Add BTF_SET_START/END macros Jiri Olsa
2020-08-05  6:29   ` Andrii Nakryiko
2020-08-01 17:03 ` [PATCH v9 bpf-next 10/14] bpf: Add d_path helper Jiri Olsa
2020-08-02  3:13   ` Alexei Starovoitov
2020-08-02 18:26     ` Jiri Olsa
2020-08-05  6:35   ` Andrii Nakryiko
2020-08-05 17:58     ` Jiri Olsa
2020-08-05 21:01       ` Jiri Olsa
2020-08-05 21:09         ` Andrii Nakryiko
2020-08-07  0:31   ` KP Singh
2020-08-07  8:35     ` Jiri Olsa
2020-08-07  9:42       ` KP Singh
2020-08-01 17:03 ` [PATCH v9 bpf-next 11/14] bpf: Update .BTF_ids section in btf.rst with sets info Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 12/14] selftests/bpf: Add verifier test for d_path helper Jiri Olsa
2020-08-01 17:03 ` [PATCH v9 bpf-next 13/14] selftests/bpf: Add " Jiri Olsa
2020-08-05  6:40   ` Andrii Nakryiko
2020-08-05 18:00     ` Jiri Olsa [this message]
2020-08-01 17:03 ` [PATCH v9 bpf-next 14/14] selftests/bpf: Add set test to resolve_btfids Jiri Olsa
2020-08-05  6:41   ` Andrii Nakryiko

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