[gentoo-commits] proj/linux-patches:6.10 commit in: /

["Mike Pagano" <mpagano@gentoo.org>]

commit:     e6e998f862f051598cd9b9c6cdcb7ad1f9f16d65
Author:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
AuthorDate: Sat Sep  7 14:26:05 2024 +0000
Commit:     Mike Pagano <mpagano <AT> gentoo <DOT> org>
CommitDate: Sat Sep  7 14:26:05 2024 +0000
URL:        https://gitweb.gentoo.org/proj/linux-patches.git/commit/?id=e6e998f8

libbpf: workaround (another) -Wmaybe-uninitialized false positive

Thanks to Sam

Signed-off-by: Mike Pagano <mpagano <AT> gentoo.org>

 0000_README                                        |  4 ++
 ...workaround-Wmaybe-uninitialized-false-pos.patch | 64 ++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/0000_README b/0000_README
index ad96829d..9948b161 100644
--- a/0000_README
+++ b/0000_README
@@ -111,6 +111,10 @@ Patch:  2910_bfp-mark-get-entry-ip-as--maybe-unused.patch
 From:   https://www.spinics.net/lists/stable/msg604665.html
 Desc:   bpf: mark get_entry_ip as __maybe_unused
 
+Patch:  2911_libbpf-second-workaround-Wmaybe-uninitialized-false-pos.patch
+From:   https://lore.kernel.org/bpf/f6962729197ae7cdf4f6d1512625bd92f2322d31.1725630494.git.sam@gentoo.org/
+Desc:   libbpf: workaround (another) -Wmaybe-uninitialized false positive
+
 Patch:  2920_sign-file-patch-for-libressl.patch
 From:   https://bugs.gentoo.org/717166
 Desc:   sign-file: full functionality with modern LibreSSL

diff --git a/2911_libbpf-second-workaround-Wmaybe-uninitialized-false-pos.patch b/2911_libbpf-second-workaround-Wmaybe-uninitialized-false-pos.patch
new file mode 100644
index 00000000..f01221c7
--- /dev/null
+++ b/2911_libbpf-second-workaround-Wmaybe-uninitialized-false-pos.patch
@@ -0,0 +1,64 @@
+From git@z Thu Jan  1 00:00:00 1970
+Subject: [PATCH] libbpf: workaround (another) -Wmaybe-uninitialized false
+ positive
+From: Sam James <sam@gentoo.org>
+Date: Fri, 06 Sep 2024 14:48:14 +0100
+Message-Id: <f6962729197ae7cdf4f6d1512625bd92f2322d31.1725630494.git.sam@gentoo.org>
+MIME-Version: 1.0
+Content-Type: text/plain; charset="utf-8"
+Content-Transfer-Encoding: 8bit
+
+We get this with GCC 15 -O3 (at least):
+```
+libbpf.c: In function ‘bpf_map__init_kern_struct_ops’:
+libbpf.c:1109:18: error: ‘mod_btf’ may be used uninitialized [-Werror=maybe-uninitialized]
+ 1109 |         kern_btf = mod_btf ? mod_btf->btf : obj->btf_vmlinux;
+      |         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+libbpf.c:1094:28: note: ‘mod_btf’ was declared here
+ 1094 |         struct module_btf *mod_btf;
+      |                            ^~~~~~~
+In function ‘find_struct_ops_kern_types’,
+    inlined from ‘bpf_map__init_kern_struct_ops’ at libbpf.c:1102:8:
+libbpf.c:982:21: error: ‘btf’ may be used uninitialized [-Werror=maybe-uninitialized]
+  982 |         kern_type = btf__type_by_id(btf, kern_type_id);
+      |                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+libbpf.c: In function ‘bpf_map__init_kern_struct_ops’:
+libbpf.c:967:21: note: ‘btf’ was declared here
+  967 |         struct btf *btf;
+      |                     ^~~
+```
+
+This is similar to the other libbpf fix from a few weeks ago for
+the same modelling-errno issue (fab45b962749184e1a1a57c7c583782b78fad539).
+
+Link: https://bugs.gentoo.org/939106
+Signed-off-by: Sam James <sam@gentoo.org>
+---
+ tools/lib/bpf/libbpf.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
+index a3be6f8fac09e..7315120574c29 100644
+--- a/tools/lib/bpf/libbpf.c
++++ b/tools/lib/bpf/libbpf.c
+@@ -988,7 +988,7 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
+ {
+ 	const struct btf_type *kern_type, *kern_vtype;
+ 	const struct btf_member *kern_data_member;
+-	struct btf *btf;
++	struct btf *btf = NULL;
+ 	__s32 kern_vtype_id, kern_type_id;
+ 	char tname[256];
+ 	__u32 i;
+@@ -1115,7 +1115,7 @@ static int bpf_map__init_kern_struct_ops(struct bpf_map *map)
+ 	const struct btf *btf = obj->btf;
+ 	struct bpf_struct_ops *st_ops;
+ 	const struct btf *kern_btf;
+-	struct module_btf *mod_btf;
++	struct module_btf *mod_btf = NULL;
+ 	void *data, *kern_data;
+ 	const char *tname;
+ 	int err;
+-- 
+2.46.0
+