fs/netfs/read_retry.c:235:20: error: variable 'subreq' is uninitialized when used here [-Werror,-Wuninitialized]

Naresh Kamboju
2024-11-26T08:25:24Z

The x86_64 builds failed with clang-19 and clang-nightly on the Linux
next-20241125 tag.
Same build pass with gcc-13.

First seen on Linux next-20241125 tag.
Good: next-20241122
Bad: next-20241125 and next-20241126

x86_64:
build:
* clang-19-lkftconfig
* clang-nightly-lkftconfig-lto-full
* clang-nightly-lkftconfig
* clang-19-lkftconfig-kcsan
* korg-clang-19-lkftconfig-lto-full
* clang-nightly-lkftconfig-lto-thing
* clang-nightly-lkftconfig-kselftest
* clang-19-x86_64_defconfig
* rustclang-nightly-lkftconfig-kselftest
* clang-19-lkftconfig-no-kselftest-frag
* korg-clang-19-lkftconfig-hardening
* korg-clang-19-lkftconfig-lto-thing
* clang-19-lkftconfig-compat
* clang-nightly-lkftconfig-hardening
* clang-nightly-x86_64_defconfig

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>

Build error:
---------
fs/netfs/read_retry.c:235:20: error: variable 'subreq' is
uninitialized when used here [-Werror,-Wuninitialized]
235 | if (list_is_last(&subreq->rreq_link, &stream->subrequests))
| ^~~~~~
fs/netfs/read_retry.c:28:36: note: initialize the variable 'subreq' to
silence this warning
28 | struct netfs_io_subrequest *subreq;
| ^
| = NULL
1 error generated.
make[5]: *** [scripts/Makefile.build:194: fs/netfs/read_retry.o] Error 1

Build image:
-----------
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241126/testrun/26060810/suite/build/test/clang-19-lkftconfig/log
- https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20241126/testrun/26060810/suite/build/test/clang-19-lkftconfig/details/
- https://storage.tuxsuite.com/public/linaro/lkft/builds/2pNKzjvChfT6aOWplZaZeQzbYCX/

Steps to reproduce:
------------
- tuxmake --runtime podman --target-arch x86_64 --toolchain clang-19
--kconfig https://storage.tuxsuite.com/public/linaro/lkft/builds/2pNKzjvChfT6aOWplZaZeQzbYCX/config
LLVM=1 LLVM_IAS=1

The git log shows
$ git log --oneline next-20241122..next-20241125 -- fs/netfs/read_retry.c
1bd9011ee163e netfs: Change the read result collector to only use one work item
5c962f9982cd9 netfs: Don't use bh spinlock
3c8a83f74e0ea netfs: Drop the was_async arg from netfs_read_subreq_terminated()
2029a747a14d2 netfs: Abstract out a rolling folio buffer implementation

metadata:
----
git describe: next-20241125 and next-20241126
git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git sha: ed9a4ad6e5bd3a443e81446476718abebee47e82
kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/2pNKzjvChfT6aOWplZaZeQzbYCX/config
build url: https://storage.tuxsuite.com/public/linaro/lkft/builds/2pNKzjvChfT6aOWplZaZeQzbYCX/
toolchain: clang-19 and clang-nightly
config: defconfig, lkftconfig etc
arch: x86_64

--
Linaro LKFT