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1b19b95169
A warning that I thought I had fixed before occasionally comes
back in rare randconfig builds (I found 7 instances in the last
100000 builds, originally it was much more frequent):
drivers/infiniband/hw/mlx5/mr.c: In function 'mlx5_ib_reg_user_mr':
drivers/infiniband/hw/mlx5/mr.c:1229:5: error: 'order' may be used uninitialized in this function [-Werror=maybe-uninitialized]
if (order <= mr_cache_max_order(dev)) {
^
drivers/infiniband/hw/mlx5/mr.c:1247:8: error: 'ncont' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/infiniband/hw/mlx5/mr.c:1247:8: error: 'page_shift' may be used uninitialized in this function [-Werror=maybe-uninitialized]
drivers/infiniband/hw/mlx5/mr.c:1260:2: error: 'npages' may be used uninitialized in this function [-Werror=maybe-uninitialized]
I've looked at all those findings again and noticed that they are all
with CONFIG_INFINIBAND_USER_MEM=n, which means ib_umem_get() returns
an error unconditionally and we never initialize or use those variables.
This triggers a condition in gcc iff mr_umem_get() is partially but not
entirely inlined, which in turn depends on the exact combination of
optimization settings. This is a known problem with gcc, with no
easy solution in the compiler, so this adds another workaround that
should be more reliable than my previous attempt.
Returning an error from mlx5_ib_reg_user_mr() earlier means that we
can completely bypass the logic that caused the warning, the compiler
can now see that the variable is never accessed.
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.