Commit 99ea1521 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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()
parents 427714f2 63a0895d

Documentation/process/deprecated.rst

+18 −0
Original line number Diff line number Diff line
@@ -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

arch/arm/mach-sa1100/assabet.c

+1 −1
Original line number Diff line number Diff line
@@ -652,7 +652,7 @@ static void __init map_sa1100_gpio_regs( void ) 
 */

static void __init get_assabet_scr(void)

{

	unsigned long uninitialized_var(scr), i;

	unsigned long scr, i;



	GPDR |= 0x3fc;			/* Configure GPIO 9:2 as outputs */

	GPSR = 0x3fc;			/* Write 0xFF to GPIO 9:2 */

arch/arm/mm/alignment.c

+1 −1
Original line number Diff line number Diff line
@@ -799,7 +799,7 @@ static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst) 
static int

do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)

{

	union offset_union uninitialized_var(offset);

	union offset_union offset;

	unsigned long instrptr;

	int (*handler)(unsigned long addr, u32 instr, struct pt_regs *regs);

	unsigned int type;

arch/ia64/kernel/process.c

+1 −1
Original line number Diff line number Diff line
@@ -445,7 +445,7 @@ static void 
do_copy_task_regs (struct task_struct *task, struct unw_frame_info *info, void *arg)

{

	unsigned long mask, sp, nat_bits = 0, ar_rnat, urbs_end, cfm;

	unsigned long uninitialized_var(ip);	/* GCC be quiet */

	unsigned long ip;

	elf_greg_t *dst = arg;

	struct pt_regs *pt;

	char nat;

arch/ia64/mm/discontig.c

+1 −1
Original line number Diff line number Diff line
@@ -180,7 +180,7 @@ static void *per_cpu_node_setup(void *cpu_data, int node) 
void __init setup_per_cpu_areas(void)

{

	struct pcpu_alloc_info *ai;

	struct pcpu_group_info *uninitialized_var(gi);

	struct pcpu_group_info *gi;

	unsigned int *cpu_map;

	void *base;

	unsigned long base_offset;

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