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From:   Kuniyuki Iwashima <kuniyu@amazon.com>
To:     <linmiaohe@huawei.com>
CC:     <davem@davemloft.net>, <edumazet@google.com>, <kuba@kernel.org>,
        <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
        <pabeni@redhat.com>, <kuniyu@amazon.com>
Subject: Re: [PATCH] net: skbuff: fix missing a __noreturn annotation warning
Date:   Fri, 26 May 2023 21:00:38 -0700
Message-ID: <20230527040038.6783-1-kuniyu@amazon.com>
In-Reply-To: <20230527110409.497408-1-linmiaohe@huawei.com>
References: <20230527110409.497408-1-linmiaohe@huawei.com>
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From: Miaohe Lin <linmiaohe@huawei.com>
Date: Sat, 27 May 2023 19:04:09 +0800
> Add __noreturn annotation to fix the warning:
>  net/core/skbuff.o: warning: objtool: skb_push+0x3c: skb_panic() is missing a __noreturn annotation
>  net/core/skbuff.o: warning: objtool: skb_put+0x4e: skb_panic() is missing a __noreturn annotation

What arch are you using ?

IIUC, BUG() should have an annotation for objtool, for
example, __builtin_unreachable() for x86.

Maybe the arch is missing such an annotation ?

Also I'm curious why objtool complains about only skb_push(),
there should be more non-inline functions that has BUG().

Thanks,
Kuniyuki


> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>  net/core/skbuff.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 6724a84ebb09..12b525aa4783 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -181,8 +181,8 @@ EXPORT_SYMBOL_GPL(drop_reasons_unregister_subsys);
>   *	Keep out of line to prevent kernel bloat.
>   *	__builtin_return_address is not used because it is not always reliable.
>   */
> -static void skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
> -		      const char msg[])
> +static void __noreturn skb_panic(struct sk_buff *skb, unsigned int sz, void *addr,
> +				 const char msg[])
>  {
>  	pr_emerg("%s: text:%px len:%d put:%d head:%px data:%px tail:%#lx end:%#lx dev:%s\n",
>  		 msg, addr, skb->len, sz, skb->head, skb->data,
> -- 
> 2.27.0