Re: [PATCH] Bluetooth: hci_core: Use ERR_PTR instead of NULL

From: Pavel Skripkin <paskripkin@gmail.com>
To: Khalid Masum <khalid.masum.92@gmail.com>,
	linux-kernel-mentees@lists.linuxfoundation.org,
	linux-kernel@vger.kernel.org
Cc: Johan Hedberg <johan.hedberg@gmail.com>,
	netdev@vger.kernel.org, Marcel Holtmann <marcel@holtmann.org>,
	linux-bluetooth@vger.kernel.org,
	Eric Dumazet <edumazet@google.com>,
	Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	"David S . Miller" <davem@davemloft.net>
Subject: Re: [PATCH] Bluetooth: hci_core: Use ERR_PTR instead of NULL
Date: Sun, 17 Jul 2022 19:17:33 +0300	[thread overview]
Message-ID: <3ea0ea90-48bf-ce19-e014-9443d732e831@gmail.com> (raw)
In-Reply-To: <20220717133759.8479-1-khalid.masum.92@gmail.com>

Hi Khalid,

Khalid Masum <khalid.masum.92@gmail.com> says:
> Failure of kzalloc to allocate memory is not reported. Return Error
> pointer to ENOMEM if memory allocation fails. This will increase
> readability and will make the function easier to use in future.
> 
> Signed-off-by: Khalid Masum <khalid.masum.92@gmail.com>
> ---

[snip]

> index a0f99baafd35..ea50767e02bf 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -2419,7 +2419,7 @@ struct hci_dev *hci_alloc_dev_priv(int sizeof_priv)
>   
>   	hdev = kzalloc(alloc_size, GFP_KERNEL);
>   	if (!hdev)
> -		return NULL;
> +		return ERR_PTR(-ENOMEM);
>   

This will break all callers of hci_alloc_dev(). All callers expect NULL 
in case of an error, so you will leave them with wrong pointer.

Also, allocation functionS return an error only in case of ENOMEM, so 
initial code is fine, IMO

Thanks,
--Pavel Skripkin
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