linux-kernel - Re: [PATCH v2] io_uring: releasing CPU resources when polling

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Message-ID: <CAFBCWQJAjef4AGXmVDZ-dR02zqstpXuP_mWimsF5HQCMxxeCcg@mail.gmail.com>
Date: Fri, 19 Apr 2024 16:09:56 +0700
From: Ammar Faizi <ammarfaizi2@...weeb.org>
To: hexue <xue01.he@...sung.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, 
	io-uring Mailing List <io-uring@...r.kernel.org>, Jens Axboe <axboe@...nel.dk>, 
	Pavel Begunkov <asml.silence@...il.com>, Kanchan Joshi <joshi.k@...sung.com>, 
	Kundan Kumar <kundan.kumar@...sung.com>, Anuj Gupta <anuj20.g@...sung.com>, 
	Wenwen Chen <wenwen.chen@...sung.com>, Ruyi Zhang <ruyi.zhang@...sung.com>, 
	Xiaobing Li <xiaobing.li@...sung.com>, cliang01.li@...sung.com, peiwei.li@...sung.com
Subject: Re: [PATCH v2] io_uring: releasing CPU resources when polling

On Fri, Apr 19, 2024 at 3:47 PM hexue wrote:
> +void init_hybrid_poll_info(struct io_ring_ctx *ctx, struct io_kiocb *req)
> +{
> +       u32 index;
> +
> +       index = req->file->f_inode->i_rdev;
> +       struct iopoll_info *entry = xa_load(&ctx->poll_array, index);
> +
> +       if (!entry) {
> +               entry = kmalloc(sizeof(struct iopoll_info), GFP_KERNEL);
> +               entry->last_runtime = 0;
> +               entry->last_irqtime = 0;
> +               xa_store(&ctx->poll_array, index, entry, GFP_KERNEL);
> +       }

GFP_KERNEL may fail; you must check for failure. Otherwise, it could
lead to NULL pointer dereference.

-- 
Ammar Faizi