treewide: Remove uninitialized_var() usage

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(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.

In preparation for removing[2] the[3] macro[4], remove all remaining
needless uses with the following script:

git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \
	xargs perl -pi -e \
		's/\buninitialized_var\(([^\)]+)\)/\1/g;
		 s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;'

drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid
pathological white-space.

No outstanding warnings were found building allmodconfig with GCC 9.3.0
for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64,
alpha, and m68k.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5
Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB
Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers
Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs
Signed-off-by: Kees Cook <keescook@chromium.org>

9 files changed, 12 insertions, 12 deletions

diff --git a/mm/frontswap.c b/mm/frontswap.c
index bfa3a339253e..9d977b1fc016 100644
--- a/mm/frontswap.c
+++ b/mm/frontswap.c
@@ -446,7 +446,7 @@ static int __frontswap_shrink(unsigned long target_pages,
 void frontswap_shrink(unsigned long target_pages)
 {
 	unsigned long pages_to_unuse = 0;
-	int uninitialized_var(type), ret;
+	int type, ret;
 
 	/*
 	 * we don't want to hold swap_lock while doing a very
diff --git a/mm/ksm.c b/mm/ksm.c
index 4102034cd55a..5fb176d497ea 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -2387,7 +2387,7 @@ next_mm:
 static void ksm_do_scan(unsigned int scan_npages)
 {
 	struct rmap_item *rmap_item;
-	struct page *uninitialized_var(page);
+	struct page *page;
 
 	while (scan_npages-- && likely(!freezing(current))) {
 		cond_resched();
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 19622328e4b5..c888d9b5c745 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1004,7 +1004,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 				   struct mem_cgroup *prev,
 				   struct mem_cgroup_reclaim_cookie *reclaim)
 {
-	struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
+	struct mem_cgroup_reclaim_iter *iter;
 	struct cgroup_subsys_state *css = NULL;
 	struct mem_cgroup *memcg = NULL;
 	struct mem_cgroup *pos = NULL;
diff --git a/mm/memory.c b/mm/memory.c
index 87ec87cdc1ff..5b5887b0e7f4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2205,7 +2205,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
 {
 	pte_t *pte;
 	int err = 0;
-	spinlock_t *uninitialized_var(ptl);
+	spinlock_t *ptl;
 
 	if (create) {
 		pte = (mm == &init_mm) ?
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 381320671677..b9e85d467352 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1234,7 +1234,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
 static struct page *new_page(struct page *page, unsigned long start)
 {
 	struct vm_area_struct *vma;
-	unsigned long uninitialized_var(address);
+	unsigned long address;
 
 	vma = find_vma(current->mm, start);
 	while (vma) {
@@ -1629,7 +1629,7 @@ static int kernel_get_mempolicy(int __user *policy,
 				unsigned long flags)
 {
 	int err;
-	int uninitialized_var(pval);
+	int pval;
 	nodemask_t nodes;
 
 	addr = untagged_addr(addr);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 48eb0f1410d4..b52a3a2a5edd 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -961,7 +961,7 @@ static inline void __free_one_page(struct page *page,
 		int migratetype, bool report)
 {
 	struct capture_control *capc = task_capc(zone);
-	unsigned long uninitialized_var(buddy_pfn);
+	unsigned long buddy_pfn;
 	unsigned long combined_pfn;
 	unsigned int max_order;
 	struct page *buddy;
diff --git a/mm/percpu.c b/mm/percpu.c
index 696367b18222..b626766160ce 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2513,7 +2513,7 @@ static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
 	const size_t static_size = __per_cpu_end - __per_cpu_start;
 	int nr_groups = 1, nr_units = 0;
 	size_t size_sum, min_unit_size, alloc_size;
-	int upa, max_upa, uninitialized_var(best_upa);	/* units_per_alloc */
+	int upa, max_upa, best_upa;	/* units_per_alloc */
 	int last_allocs, group, unit;
 	unsigned int cpu, tcpu;
 	struct pcpu_alloc_info *ai;
diff --git a/mm/slub.c b/mm/slub.c
index ef303070d175..f226d66408ee 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1218,7 +1218,7 @@ static noinline int free_debug_processing(
 	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
 	void *object = head;
 	int cnt = 0;
-	unsigned long uninitialized_var(flags);
+	unsigned long flags;
 	int ret = 0;
 
 	spin_lock_irqsave(&n->list_lock, flags);
@@ -2901,7 +2901,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page,
 	struct page new;
 	unsigned long counters;
 	struct kmem_cache_node *n = NULL;
-	unsigned long uninitialized_var(flags);
+	unsigned long flags;
 
 	stat(s, FREE_SLOWPATH);
 
diff --git a/mm/swap.c b/mm/swap.c
index a82efc33411f..de257c0a89b1 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -830,8 +830,8 @@ void release_pages(struct page **pages, int nr)
 	LIST_HEAD(pages_to_free);
 	struct pglist_data *locked_pgdat = NULL;
 	struct lruvec *lruvec;
-	unsigned long uninitialized_var(flags);
-	unsigned int uninitialized_var(lock_batch);
+	unsigned long flags;
+	unsigned int lock_batch;
 
 	for (i = 0; i < nr; i++) {
 		struct page *page = pages[i];