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From: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
To: Audra Mitchell <audra@redhat.com>, linux-kernel@vger.kernel.org
Cc: tj@kernel.org, jiangshanlai@gmail.com,
	hirokazu.yamauchi.hk@hitachi.com, ddouwsma@redhat.com,
	loberman@redhat.com, raquini@redhat.com
Subject: Re: [PATCH v2] workqueue.c: Increase workqueue name length
Date: Wed, 10 Jan 2024 21:47:56 +0100	[thread overview]
Message-ID: <2f0efed5-f9f3-4a5c-9fd4-a4837cada298@prevas.dk> (raw)
In-Reply-To: <20240110202959.249296-1-audra@redhat.com>

On 10/01/2024 21.29, Audra Mitchell wrote:

> @@ -4663,9 +4663,10 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
>  					 unsigned int flags,
>  					 int max_active, ...)
>  {
> -	va_list args;
> +	va_list args, args_copy;
>  	struct workqueue_struct *wq;
>  	struct pool_workqueue *pwq;
> +	int len;
>  
>  	/*
>  	 * Unbound && max_active == 1 used to imply ordered, which is no longer
> @@ -4692,6 +4693,13 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
>  	}
>  
>  	va_start(args, max_active);
> +	va_copy(args_copy, args);
> +	len = vsnprintf(NULL, 0, fmt, args_copy);
> +	WARN(len > WQ_NAME_LEN,
> +		"workqueue: wq->name too long (%d). Truncated to WQ_NAME_LEN (%d)\n",
> +		len, WQ_NAME_LEN);
> +
> +	va_end(args_copy);
>  	vsnprintf(wq->name, sizeof(wq->name), fmt, args);

Eh, why not just _not_ throw away the return value from the existing
vsnprintf() and do "len >= sizeof(wq->name)" to know if truncation
happened? There's really no need need to do vsnprintf() twice. (And yes,
you want >=, not >).

Oh, and definitely not WARN,  pr_warn() or pr_warn_once() please.

Rasmus


  reply	other threads:[~2024-01-10 20:48 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-15 19:39 [PATCH] workqueue.c: Change workqueue to accept variable length name Audra Mitchell
2023-12-21 21:39 ` Tejun Heo
     [not found]   ` <CA+bDH-v6T5vvyOwsphseHwgihdGQta7TZ9tOtt-Fnij92kvU6A@mail.gmail.com>
2023-12-22 17:53     ` Tejun Heo
2024-01-09 13:29       ` Audra Mitchell
2024-01-10 20:29 ` [PATCH v2] workqueue.c: Increase workqueue name length Audra Mitchell
2024-01-10 20:47   ` Rasmus Villemoes [this message]
2024-01-10 21:52     ` Rafael Aquini
2024-01-10 22:06       ` Rasmus Villemoes
2024-01-10 22:31         ` Rafael Aquini
2024-01-10 22:45           ` Rafael Aquini
2024-01-10 22:58             ` Rasmus Villemoes
2024-01-10 22:52           ` Rasmus Villemoes
2024-01-10 23:08             ` Rafael Aquini
2024-01-15 17:08 ` [PATCH v3] " Audra Mitchell
2024-01-16 18:31   ` Tejun Heo
2024-01-17 14:40     ` Audra Mitchell
2024-01-17 17:09       ` Tejun Heo
2024-01-19 20:30         ` Audra Mitchell
2024-01-19 23:44           ` Tejun Heo

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