[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <d7fa9cf7-7c7e-b01c-8925-ce6dafc8721c@gmail.com>
Date: Mon, 7 May 2018 11:14:02 -0700
From: Florian Fainelli <f.fainelli@...il.com>
To: Salvatore Mesoraca <s.mesoraca16@...il.com>, Andrew Lunn <andrew@...n.ch>
Cc: linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
Kees Cook <keescook@...omium.org>,
Vivien Didelot <vivien.didelot@...oirfairelinux.com>,
David Laight <David.Laight@...LAB.COM>
Subject: Re: [PATCH v2] net: dsa: drop some VLAs in switch.c
On 05/07/2018 08:23 AM, Salvatore Mesoraca wrote:
> We avoid 2 VLAs by using a pre-allocated field in dsa_switch.
> We also try to avoid dynamic allocation whenever possible.
>
> Link: http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
> Link: http://lkml.kernel.org/r/20180505185145.GB32630@lunn.ch
>
> Signed-off-by: Salvatore Mesoraca <s.mesoraca16@...il.com>
> ---
> include/net/dsa.h | 3 +++
> net/dsa/dsa2.c | 14 ++++++++++++++
> net/dsa/switch.c | 22 ++++++++++------------
> 3 files changed, 27 insertions(+), 12 deletions(-)
>
> diff --git a/include/net/dsa.h b/include/net/dsa.h
> index 60fb4ec..576791d 100644
> --- a/include/net/dsa.h
> +++ b/include/net/dsa.h
> @@ -256,6 +256,9 @@ struct dsa_switch {
> /* Number of switch port queues */
> unsigned int num_tx_queues;
>
> + unsigned long *bitmap;
> + unsigned long _bitmap;
> +
> /* Dynamically allocated ports, keep last */
> size_t num_ports;
> struct dsa_port ports[];
> diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
> index adf50fb..cebf35f0 100644
> --- a/net/dsa/dsa2.c
> +++ b/net/dsa/dsa2.c
> @@ -748,6 +748,20 @@ struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n)
> if (!ds)
> return NULL;
>
> + /* We avoid allocating memory outside dsa_switch
> + * if it is not needed.
> + */
> + if (n <= sizeof(ds->_bitmap) * 8) {
> + ds->bitmap = &ds->_bitmap;
Should not this be / BITS_PER_BYTE? If the sizeof(unsigned long) is <=
8, then you don't need to allocate it, otherwise, you have to.
I would actually just always dynamically allocate the bitmap, optimizing
for the case where we have fewer than or 8 ports is not worth IMHO.
--
Florian
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
