linux-kernel - Re: [PATCH v4] erofs: lazily initialize per-CPU workers and CPU hotplug hooks

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Message-ID: <94c702b9-cad5-4727-a7f1-16de1827841e@linux.alibaba.com>
Date: Thu, 24 Apr 2025 08:31:42 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: Sandeep Dhavale <dhavale@...gle.com>, linux-erofs@...ts.ozlabs.org,
 Gao Xiang <xiang@...nel.org>, Chao Yu <chao@...nel.org>,
 Yue Hu <zbestahu@...il.com>, Jeffle Xu <jefflexu@...ux.alibaba.com>
Cc: kernel-team@...roid.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] erofs: lazily initialize per-CPU workers and CPU
 hotplug hooks



On 2025/4/23 14:10, Sandeep Dhavale wrote:
> Currently, when EROFS is built with per-CPU workers, the workers are
> started and CPU hotplug hooks are registered during module initialization.
> This leads to unnecessary worker start/stop cycles during CPU hotplug
> events, particularly on Android devices that frequently suspend and resume.
> 
> This change defers the initialization of per-CPU workers and the
> registration of CPU hotplug hooks until the first EROFS mount. This
> ensures that these resources are only allocated and managed when EROFS is
> actually in use.
> 
> The tear down of per-CPU workers and unregistration of CPU hotplug hooks
> still occurs during z_erofs_exit_subsystem(), but only if they were
> initialized.
> 
> Signed-off-by: Sandeep Dhavale <dhavale@...gle.com>

Reviewed-by: Gao Xiang <hsiangkao@...ux.alibaba.com>

> ---

...

>   int z_erofs_init_super(struct super_block *sb)
>   {
> -	struct inode *const inode = new_inode(sb);
> +	struct inode *inode;
> +	int err;
>   
> +	err = z_erofs_init_pcpu_workers();
> +	if (err)
> +		return err;
> +
> +	inode = new_inode(sb);
>   	if (!inode)
>   		return -ENOMEM;
> +

I think the new blank line is redundant, the setup part
should be next to new_inode().

I could fix up this part manually if you don't have strong
opinion on this.

Thanks,
Gao Xiang