linux-kernel - Re: [PATCH 2/4] timerfd: convert to ->read

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Message-ID: <1a1c00fb-c83f-44e7-bc6a-cfe52d780c35@kernel.dk>
Date: Wed, 10 Apr 2024 16:27:14 -0600
From: Jens Axboe <axboe@...nel.dk>
To: linux-fsdevel@...r.kernel.org
Cc: brauner@...nel.org, linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk
Subject: Re: [PATCH 2/4] timerfd: convert to ->read_iter()

On 4/9/24 9:22 AM, Jens Axboe wrote:
> @@ -312,8 +313,8 @@ static ssize_t timerfd_read(struct file *file, char __user *buf, size_t count,
>  		ctx->ticks = 0;
>  	}
>  	spin_unlock_irq(&ctx->wqh.lock);
> -	if (ticks)
> -		res = put_user(ticks, (u64 __user *) buf) ? -EFAULT: sizeof(ticks);
> +	if (ticks && !copy_to_iter_full(&ticks, sizeof(ticks), to))
> +		res = -EFAULT;
>  	return res;
>  }

Dumb thinko here, as that should be:

if (ticks) {                                                            
	res = copy_to_iter(&ticks, sizeof(ticks), to);                  
	if (!res)                                                       
		res = -EFAULT;                                          
}            

I've updated my branch, just a heads-up. Odd how it passing testing,
guess I got stack lucky...

-- 
Jens Axboe