linux-kernel - Re: [PATCH] mm: Use fallthrough;

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Date:   Sat, 7 Mar 2020 12:53:02 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Joe Perches <joe@...ches.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Hugh Dickins <hughd@...gle.com>,
        Minchan Kim <minchan@...nel.org>,
        Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org
Subject: Re: [PATCH] mm: Use fallthrough;



On 3/7/20 01:58, Joe Perches wrote:
> Convert the various /* fallthrough */ comments to the
> pseudo-keyword fallthrough;
> 
> Done via script:
> https://lore.kernel.org/lkml/b56602fcf79f849e733e7b521bb0e17895d390fa.1582230379.git.joe@perches.com/
> 
> Signed-off-by: Joe Perches <joe@...ches.com>

Reviewed-by: Gustavo A. R. Silva <gustavo@...eddedor.com>

> ---
> 
> Might as well start with fallthrough conversions somewhere...
> 
>  mm/gup.c            | 2 +-
>  mm/hugetlb_cgroup.c | 6 +++---
>  mm/ksm.c            | 3 +--
>  mm/list_lru.c       | 2 +-
>  mm/memcontrol.c     | 2 +-
>  mm/mempolicy.c      | 3 ---
>  mm/mmap.c           | 5 ++---
>  mm/shmem.c          | 2 +-
>  mm/zsmalloc.c       | 2 +-
>  9 files changed, 11 insertions(+), 16 deletions(-)
> 
> diff --git a/mm/gup.c b/mm/gup.c
> index f58929..4bfd753 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1072,7 +1072,7 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
>  				goto retry;
>  			case -EBUSY:
>  				ret = 0;
> -				/* FALLTHRU */
> +				fallthrough;
>  			case -EFAULT:
>  			case -ENOMEM:
>  			case -EHWPOISON:
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index 790f63..7994eb8 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -468,14 +468,14 @@ static int hugetlb_cgroup_read_u64_max(struct seq_file *seq, void *v)
>  	switch (MEMFILE_ATTR(cft->private)) {
>  	case RES_RSVD_USAGE:
>  		counter = &h_cg->rsvd_hugepage[idx];
> -		/* Fall through. */
> +		fallthrough;
>  	case RES_USAGE:
>  		val = (u64)page_counter_read(counter);
>  		seq_printf(seq, "%llu\n", val * PAGE_SIZE);
>  		break;
>  	case RES_RSVD_LIMIT:
>  		counter = &h_cg->rsvd_hugepage[idx];
> -		/* Fall through. */
> +		fallthrough;
>  	case RES_LIMIT:
>  		val = (u64)counter->max;
>  		if (val == limit)
> @@ -515,7 +515,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
>  	switch (MEMFILE_ATTR(of_cft(of)->private)) {
>  	case RES_RSVD_LIMIT:
>  		rsvd = true;
> -		/* Fall through. */
> +		fallthrough;
>  	case RES_LIMIT:
>  		mutex_lock(&hugetlb_limit_mutex);
>  		ret = page_counter_set_max(
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 363ec8..a558da9 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -2813,8 +2813,7 @@ static int ksm_memory_callback(struct notifier_block *self,
>  		 */
>  		ksm_check_stable_tree(mn->start_pfn,
>  				      mn->start_pfn + mn->nr_pages);
> -		/* fallthrough */
> -
> +		fallthrough;
>  	case MEM_CANCEL_OFFLINE:
>  		mutex_lock(&ksm_thread_mutex);
>  		ksm_run &= ~KSM_RUN_OFFLINE;
> diff --git a/mm/list_lru.c b/mm/list_lru.c
> index 9e4a28..87b540f 100644
> --- a/mm/list_lru.c
> +++ b/mm/list_lru.c
> @@ -223,7 +223,7 @@ __list_lru_walk_one(struct list_lru_node *nlru, int memcg_idx,
>  		switch (ret) {
>  		case LRU_REMOVED_RETRY:
>  			assert_spin_locked(&nlru->lock);
> -			/* fall through */
> +			fallthrough;
>  		case LRU_REMOVED:
>  			isolated++;
>  			nlru->nr_items--;
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1e1260..dfe191 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5756,7 +5756,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
>  		switch (get_mctgt_type(vma, addr, ptent, &target)) {
>  		case MC_TARGET_DEVICE:
>  			device = true;
> -			/* fall through */
> +			fallthrough;
>  		case MC_TARGET_PAGE:
>  			page = target.page;
>  			/*
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 6d30379..45eb0a5 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -907,7 +907,6 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
>  
>  	switch (p->mode) {
>  	case MPOL_BIND:
> -		/* Fall through */
>  	case MPOL_INTERLEAVE:
>  		*nodes = p->v.nodes;
>  		break;
> @@ -2092,7 +2091,6 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
>  		break;
>  
>  	case MPOL_BIND:
> -		/* Fall through */
>  	case MPOL_INTERLEAVE:
>  		*mask =  mempolicy->v.nodes;
>  		break;
> @@ -2359,7 +2357,6 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
>  
>  	switch (a->mode) {
>  	case MPOL_BIND:
> -		/* Fall through */
>  	case MPOL_INTERLEAVE:
>  		return !!nodes_equal(a->v.nodes, b->v.nodes);
>  	case MPOL_PREFERRED:
> diff --git a/mm/mmap.c b/mm/mmap.c
> index f8ea04..60dc38 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1457,7 +1457,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
>  			 * with MAP_SHARED to preserve backward compatibility.
>  			 */
>  			flags &= LEGACY_MAP_MASK;
> -			/* fall through */
> +			fallthrough;
>  		case MAP_SHARED_VALIDATE:
>  			if (flags & ~flags_mask)
>  				return -EOPNOTSUPP;
> @@ -1480,8 +1480,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
>  			vm_flags |= VM_SHARED | VM_MAYSHARE;
>  			if (!(file->f_mode & FMODE_WRITE))
>  				vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
> -
> -			/* fall through */
> +			fallthrough;
>  		case MAP_PRIVATE:
>  			if (!(file->f_mode & FMODE_READ))
>  				return -EACCES;
> diff --git a/mm/shmem.c b/mm/shmem.c
> index d01d5b..1e9b377 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -3992,7 +3992,7 @@ bool shmem_huge_enabled(struct vm_area_struct *vma)
>  			if (i_size >= HPAGE_PMD_SIZE &&
>  					i_size >> PAGE_SHIFT >= off)
>  				return true;
> -			/* fall through */
> +			fallthrough;
>  		case SHMEM_HUGE_ADVISE:
>  			/* TODO: implement fadvise() hints */
>  			return (vma->vm_flags & VM_HUGEPAGE);
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 2aa2d5..2f836a2b 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -424,7 +424,7 @@ static void *zs_zpool_map(void *pool, unsigned long handle,
>  	case ZPOOL_MM_WO:
>  		zs_mm = ZS_MM_WO;
>  		break;
> -	case ZPOOL_MM_RW: /* fall through */
> +	case ZPOOL_MM_RW:
>  	default:
>  		zs_mm = ZS_MM_RW;
>  		break;
> 
>