linux-kernel - Re: [PATCH 3/4] libnvdimm: eliminate two unnecessary zero initializations in badrange.c

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Date:   Thu, 27 Aug 2020 14:41:28 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Oliver O'Halloran <oohall@...il.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "Dave Jiang" <dave.jiang@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] libnvdimm: eliminate two unnecessary zero
 initializations in badrange.c

I will drop this patch, because badrange_add() is unlikely to be called.
There's no need to care about trivial performance improvements.

On 2020/8/20 22:30, Zhen Lei wrote:
> Currently, the "struct badrange_entry" has three members: start, length,
> list. In append_badrange_entry(), "start" and "length" will be assigned
> later, and "list" does not need to be initialized before calling
> list_add_tail(). That means, the kzalloc() in badrange_add() or
> alloc_and_append_badrange_entry() can be replaced with kmalloc(), because
> the zero initialization is not required.
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  drivers/nvdimm/badrange.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvdimm/badrange.c b/drivers/nvdimm/badrange.c
> index 7f78b659057902d..13145001c52ff39 100644
> --- a/drivers/nvdimm/badrange.c
> +++ b/drivers/nvdimm/badrange.c
> @@ -37,7 +37,7 @@ static int alloc_and_append_badrange_entry(struct badrange *badrange,
>  {
>  	struct badrange_entry *bre;
>  
> -	bre = kzalloc(sizeof(*bre), flags);
> +	bre = kmalloc(sizeof(*bre), flags);
>  	if (!bre)
>  		return -ENOMEM;
>  
> @@ -49,7 +49,7 @@ int badrange_add(struct badrange *badrange, u64 addr, u64 length)
>  {
>  	struct badrange_entry *bre, *bre_new;
>  
> -	bre_new = kzalloc(sizeof(*bre_new), GFP_KERNEL);
> +	bre_new = kmalloc(sizeof(*bre_new), GFP_KERNEL);
>  
>  	spin_lock(&badrange->lock);
>  
>