linux-kernel - Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

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Message-ID: <aJoHzTKO9xw2CANn@black.igk.intel.com>
Date: Mon, 11 Aug 2025 17:10:05 +0200
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Bhupesh <bhupesh@...lia.com>
Cc: akpm@...ux-foundation.org, kernel-dev@...lia.com,
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Subject: Re: [PATCH v7 2/4] include: Set tsk->comm length to 64 bytes

On Mon, Aug 11, 2025 at 12:16:07PM +0530, Bhupesh wrote:
> Historically due to the 16-byte length of TASK_COMM_LEN, the
> users of 'tsk->comm' are restricted to use a fixed-size target
> buffer also of TASK_COMM_LEN for 'memcpy()' like use-cases.
> 
> To fix the same, we now use a 64-byte TASK_COMM_EXT_LEN and
> set the comm element inside 'task_struct' to the same length:
>        struct task_struct {
> 	       .....
>                char    comm[TASK_COMM_EXT_LEN];
> 	       .....
>        };
> 
>        where TASK_COMM_EXT_LEN is 64-bytes.
> 
> Note, that the existing users have not been modified to migrate to
> 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of
> dealing with only a 'TASK_COMM_LEN' long 'tsk->comm'.

...

> -	BUILD_BUG_ON(sizeof(from) != TASK_COMM_LEN);	\
> +	BUILD_BUG_ON(sizeof(from) < TASK_COMM_LEN);	\

Wondering if we may convert this to static_assert().
(rather in a separate patch)

-- 
With Best Regards,
Andy Shevchenko