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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-04 13:49:43 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-04 13:49:43 -0700 |
| commit | 99ea1521a097db51f0f04f54cfbd3b0ed119d2f1 (patch) | |
| tree | a89402c9c9cef2feecfc67144e3102240094095a /Documentation/process | |
| parent | 427714f258a3783b15e33d6daa34d57824f28bab (diff) | |
| parent | 63a0895d960aa3d3653ef0ecad5bd8579388f14b (diff) | |
| download | linux-99ea1521a097db51f0f04f54cfbd3b0ed119d2f1.tar.bz2 | |
Merge tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull uninitialized_var() macro removal from Kees Cook:
"This is long overdue, and has hidden too many bugs over the years. The
series has several "by hand" fixes, and then a trivial treewide
replacement.
- Clean up non-trivial uses of uninitialized_var()
- Update documentation and checkpatch for uninitialized_var() removal
- Treewide removal of uninitialized_var()"
* tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
compiler: Remove uninitialized_var() macro
treewide: Remove uninitialized_var() usage
checkpatch: Remove awareness of uninitialized_var() macro
mm/debug_vm_pgtable: Remove uninitialized_var() usage
f2fs: Eliminate usage of uninitialized_var() macro
media: sur40: Remove uninitialized_var() usage
KVM: PPC: Book3S PR: Remove uninitialized_var() usage
clk: spear: Remove uninitialized_var() usage
clk: st: Remove uninitialized_var() usage
spi: davinci: Remove uninitialized_var() usage
ide: Remove uninitialized_var() usage
rtlwifi: rtl8192cu: Remove uninitialized_var() usage
b43: Remove uninitialized_var() usage
drbd: Remove uninitialized_var() usage
x86/mm/numa: Remove uninitialized_var() usage
docs: deprecated.rst: Add uninitialized_var()
Diffstat (limited to 'Documentation/process')
| -rw-r--r-- | Documentation/process/deprecated.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst index 652e2aa02a66..943a926ecbbb 100644 --- a/Documentation/process/deprecated.rst +++ b/Documentation/process/deprecated.rst @@ -51,6 +51,24 @@ to make sure their systems do not continue running in the face of "unreachable" conditions. (For example, see commits like `this one <https://git.kernel.org/linus/d4689846881d160a4d12a514e991a740bcb5d65a>`_.) +uninitialized_var() +------------------- +For any compiler warnings about uninitialized variables, just add +an initializer. Using the uninitialized_var() macro (or similar +warning-silencing tricks) is dangerous as it papers over `real bugs +<https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/>`_ +(or can in the future), and suppresses unrelated compiler warnings +(e.g. "unused variable"). If the compiler thinks it is uninitialized, +either simply initialize the variable or make compiler changes. Keep in +mind that in most cases, if an initialization is obviously redundant, +the compiler's dead-store elimination pass will make sure there are no +needless variable writes. + +As Linus has said, this macro +`must <https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/>`_ +`be <https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/>`_ +`removed <https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/>`_. + open-coded arithmetic in allocator arguments -------------------------------------------- Dynamic size calculations (especially multiplication) should not be |