linux-kernel - Re: [PATCH] riscv: module: use a plain variable for list

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Message-ID: <20241127-2c074e38cc599c7e2d0da505@orel>
Date: Wed, 27 Nov 2024 15:02:35 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Clément Léger <cleger@...osinc.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	Charlie Jenkins <charlie@...osinc.com>, zhangkai@...as.ac.cn
Subject: Re: [PATCH] riscv: module: use a plain variable for list_head
 instead of a pointer

On Wed, Nov 27, 2024 at 11:30:14AM +0100, Clément Léger wrote:
> list_head does not need to be allocated, it can be a plain variable.

rel_head's list_head member, rel_entry, doesn't need to be allocated,
its storage can just be part of the allocated rel_head.

> Remove the pointer which allows to get rid of the allocation as well as
> an existing memory leak.

It'd be nice to add how the memory leak was found. Inspection or some
tool?

> 
> Signed-off-by: Clément Léger <cleger@...osinc.com>
> 
> ---
>  arch/riscv/kernel/module.c | 18 ++++--------------
>  1 file changed, 4 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
> index 1cd461f3d872..47d0ebeec93c 100644
> --- a/arch/riscv/kernel/module.c
> +++ b/arch/riscv/kernel/module.c
> @@ -23,7 +23,7 @@ struct used_bucket {
>  
>  struct relocation_head {
>  	struct hlist_node node;
> -	struct list_head *rel_entry;
> +	struct list_head rel_entry;
>  	void *location;
>  };
>  
> @@ -634,7 +634,7 @@ process_accumulated_relocations(struct module *me,
>  			location = rel_head_iter->location;
>  			list_for_each_entry_safe(rel_entry_iter,
>  						 rel_entry_iter_tmp,
> -						 rel_head_iter->rel_entry,
> +						 &rel_head_iter->rel_entry,
>  						 head) {
>  				curr_type = rel_entry_iter->type;
>  				reloc_handlers[curr_type].reloc_handler(
> @@ -704,16 +704,7 @@ static int add_relocation_to_accumulate(struct module *me, int type,
>  			return -ENOMEM;
>  		}
>  
> -		rel_head->rel_entry =
> -			kmalloc(sizeof(struct list_head), GFP_KERNEL);
> -
> -		if (!rel_head->rel_entry) {
> -			kfree(entry);
> -			kfree(rel_head);
> -			return -ENOMEM;
> -		}
> -
> -		INIT_LIST_HEAD(rel_head->rel_entry);
> +		INIT_LIST_HEAD(&rel_head->rel_entry);
>  		rel_head->location = location;
>  		INIT_HLIST_NODE(&rel_head->node);
>  		if (!current_head->first) {
> @@ -722,7 +713,6 @@ static int add_relocation_to_accumulate(struct module *me, int type,
>  
>  			if (!bucket) {
>  				kfree(entry);
> -				kfree(rel_head->rel_entry);
>  				kfree(rel_head);
>  				return -ENOMEM;
>  			}
> @@ -735,7 +725,7 @@ static int add_relocation_to_accumulate(struct module *me, int type,
>  	}
>  
>  	/* Add relocation to head of discovered rel_head */
> -	list_add_tail(&entry->head, rel_head->rel_entry);
> +	list_add_tail(&entry->head, &rel_head->rel_entry);
>  
>  	return 0;
>  }
> -- 
> 2.45.2
> 
>

Other than the commit message change suggestions,

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>