More coccinelle fixes #24606
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More coccinelle fixes #24606
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qmonnet
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CI failing because some of those |
kaworu
requested changes
Mar 28, 2023
gentoo-root
reviewed
Mar 28, 2023
GCC and clang support label attributes, such as __attribute__((unused))
to indicate that under certain configurations, (goto) labels will not be
used at compilation time. We've been using this to silence warnings
about unused labels.
However, GCC's "Attribute Syntax" documentation [0] states that:
GNU C++ only permits attributes on labels if the attribute specifier
is immediately followed by a semicolon (i.e., the label applies to
an empty statement). If the semicolon is missing, C++ label
attributes are ambiguous, as it is permissible for a declaration,
which could begin with an attribute list, to be labelled in C++.
We're using clang to compile the BPF programs and I couldn't find an
equivalent statement, but it should likely be the same. Let's add the
semi-colons.
The real motivation for this clean-up is to coccinelle parse the files
properly and to better apply checks. We've seen it struggle when the
semi-colons are missing.
[0] https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html#Label-Attributes-2
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
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So I added a new commit at the beginning, to fix a parsing issue for coccinelle that was messing up with the reports for the I also switched to |
All missing qualifiers detected by coccinelle.
The missing "const" on the "mac" argument in icmp6.h was found by
running the latest coccinelle (not 1.1.1 as in CI and Docker image) on
the bpf code base.
The missing qualifier in proxy.h was not detected so far because
coccinelle stumbles on parsing macro CTX_REDIRECT_FN in proxy.h, in
particular because of the CT_TUPLE_TYPE argument where we pass a
two-word long type (struct ipv(4|)_ct_tuple). The spatch tool would fail
with:
EXN: Failure("bpf/lib/proxy.h: 164: try to delete an expanded token: struct") in bpf/lib/proxy.h
and then would fail to detect the missing "const". By commenting out
temporarily the calls to CTX_REDIRECT_FN we make it work again. Good
news, by adding the missing "const" to "CT_TUPLE_TYPE", we're also
fixing the parsing for coccinelle, so future mistakes in the file should
be reported as expected.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Trying to create a new coccinelle check, we realised that some patterns
that we expected to match in the bpf/ were in fact never caught.
Here is a minimal reproducer.
foo.cocci:
@@
@@
(
- foo = bar;
+ foo = baz;
)
foo.c (not working):
int main (void)
{
int foo, bar, baz = 0, coccibreaker __maybe_unused;
foo = bar;
return foo;
}
Invocation:
$ docker run --rm --user 1000 \
--workdir /workspace -v `pwd`:/workspace -it
docker.io/cilium/coccicheck:2.4@sha256:24abe3fbb8e829fa41a68a3b76cb4df84fd5a87a7d1d6254c1c1fe5effb5bd1b \
spatch --include-headers --very-quiet --in-place \
--sp-file contrib/coccinelle/foo.cocci bpf/foo.c
This does not catch the "foo = bar;" statement in the C file.
However, the pattern is caught in the following file instead:
foo.c (working):
int main (void)
{
int foo, bar, baz = 0;
int coccifine __maybe_unused;
foo = bar;
return foo;
}
The __maybe_unused attribute seems to prevent spatch to parse correctly
the function. This happens independently of whether __maybe_unused is
defined in the C code. The behaviour remains the same if we replace
__maybe_unused with some other random word (although replacing it with
"__attribute__((unused))" works as expected).
Running from coccinelle's "master" branch works fine, and when running
spatch locally (no Docker image) we can also observe the following
warnings:
warning: Can't find macro file: /usr/local/bin/lib/coccinelle/standard.h
warning: Can't find default iso file: /usr/local/bin/lib/coccinelle/standard.iso
This error was fixed with commit coccinelle/coccinelle@540888ff426e
("Fix 263: wrong default path for COCCINELLE_HOME") [0], which is not
part of a release yet.
Until it is, we still want to have our code covered by coccinelle. As a
workaround to the issue, we could pass manually the paths to the files
containing the definitions for the isomorphisms and built-in macros for
coccinelle, with spatch options "--macro-file-builtin" and "--iso-file".
Even simpler, we can set $(COCCINELLE_HOME) to the correct path so that
both files are found.
No camels were harmed during this investigation.
[0] https://gitlab.inria.fr/coccinelle/coccinelle/-/commit/540888ff426e
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
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/test |
pchaigno
approved these changes
Mar 29, 2023
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In terms of tests, I don't think we need anything other than coccicheck and build datapath to pass. The first should cover the coccicheck changes and the second should be enough to cover the small changes to the C code. Marking ready to merge. |
pchaigno
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There's an outstanding change request by @kaworu. Please either dismiss it, or give him the time to resolve it. Please also triage the |
julianwiedmann
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/test-runtime |
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Review is in and I filed #24633 for the failed test, which looks like a new flake. |
dylandreimerink
approved these changes
Mar 29, 2023
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Build finished. |
gentoo-root
approved these changes
Mar 29, 2023
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runtime test succeeded, but instead of GitHub picking up the result, we have ciliumbot commenting 🤔 Anyway, this time we should be good to go. |
qmonnet
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