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()

Author: torvalds

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/[email protected]/>`_
+(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

@@ -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

@@ -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

@@ -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

@@ -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;

arch/ia64/mm/tlb.c

@@ -369,7 +369,7 @@ EXPORT_SYMBOL(flush_tlb_range);
 
 void ia64_tlb_init(void)
 {
-	ia64_ptce_info_t uninitialized_var(ptce_info); /* GCC be quiet */
+	ia64_ptce_info_t ptce_info;
 	u64 tr_pgbits;
 	long status;
 	pal_vm_info_1_u_t vm_info_1;

arch/mips/lib/dump_tlb.c

@@ -79,7 +79,7 @@ static void dump_tlb(int first, int last)
 	unsigned int pagemask, guestctl1 = 0, c0, c1, i;
 	unsigned long asidmask = cpu_asid_mask(&current_cpu_data);
 	int asidwidth = DIV_ROUND_UP(ilog2(asidmask) + 1, 4);
-	unsigned long uninitialized_var(s_mmid);
+	unsigned long s_mmid;
 #ifdef CONFIG_32BIT
 	bool xpa = cpu_has_xpa && (read_c0_pagegrain() & PG_ELPA);
 	int pwidth = xpa ? 11 : 8;

arch/mips/mm/init.c

@@ -83,7 +83,7 @@ void setup_zero_pages(void)
 static void *__kmap_pgprot(struct page *page, unsigned long addr, pgprot_t prot)
 {
 	enum fixed_addresses idx;
-	unsigned int uninitialized_var(old_mmid);
+	unsigned int old_mmid;
 	unsigned long vaddr, flags, entrylo;
 	unsigned long old_ctx;
 	pte_t pte;

arch/mips/mm/tlb-r4k.c

@@ -119,7 +119,7 @@ void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 		if (size <= (current_cpu_data.tlbsizeftlbsets ?
 			     current_cpu_data.tlbsize / 8 :
 			     current_cpu_data.tlbsize / 2)) {
-			unsigned long old_entryhi, uninitialized_var(old_mmid);
+			unsigned long old_entryhi, old_mmid;
 			int newpid = cpu_asid(cpu, mm);
 
 			old_entryhi = read_c0_entryhi();
@@ -213,7 +213,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 	int cpu = smp_processor_id();
 
 	if (cpu_context(cpu, vma->vm_mm) != 0) {
-		unsigned long uninitialized_var(old_mmid);
+		unsigned long old_mmid;
 		unsigned long flags, old_entryhi;
 		int idx;
 
@@ -382,7 +382,7 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
 #ifdef CONFIG_XPA
 	panic("Broken for XPA kernels");
 #else
-	unsigned int uninitialized_var(old_mmid);
+	unsigned int old_mmid;
 	unsigned long flags;
 	unsigned long wired;
 	unsigned long old_pagemask;

arch/powerpc/kvm/book3s_64_mmu_radix.c

@@ -33,7 +33,7 @@ unsigned long __kvmhv_copy_tofrom_guest_radix(int lpid, int pid,
 					      gva_t eaddr, void *to, void *from,
 					      unsigned long n)
 {
-	int uninitialized_var(old_pid), old_lpid;
+	int old_pid, old_lpid;
 	unsigned long quadrant, ret = n;
 	bool is_load = !!to;