xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Merge tag 'uninit-macro-v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Browse Source 
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()
This commit is contained in:
Linus Torvalds
2020-08-04 13:49:43 -07:00
parent 427714f258 63a0895d96
commit 99ea1521a0
195 changed files with 320 additions and 329 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
Documentation/process/deprecated.rst
View File

@@ -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