From: David Miller <davem@davemloft.net>
To: ben.dooks@codethink.co.uk
Cc: netdev@vger.kernel.org, David.Laight@ACULAB.COM,
oneukum@suse.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kernel@lists.codethink.co.uk
Subject: Re: [PATCH] usbnet: smsc95xx: simplify tx_fixup code
Date: Fri, 05 Oct 2018 14:24:12 -0700 (PDT) [thread overview]
Message-ID: <20181005.142412.601607260441380535.davem@davemloft.net> (raw)
In-Reply-To: <20181002165602.21033-1-ben.dooks@codethink.co.uk>
From: Ben Dooks <ben.dooks@codethink.co.uk>
Date: Tue, 2 Oct 2018 17:56:02 +0100
> - memcpy(skb->data, &tx_cmd_a, 4);
> + ptr = skb_push(skb, 8);
> + tx_cmd_a = cpu_to_le32(tx_cmd_a);
> + tx_cmd_b = cpu_to_le32(tx_cmd_b);
> + memcpy(ptr, &tx_cmd_a, 4);
> + memcpy(ptr+4, &tx_cmd_b, 4);
Even a memcpy() through a void pointer does not guarantee that gcc will
not emit word sized loads and stores.
You must use the get_unaligned()/put_unaligned() facilities to do this
properly.
I also agree that making a proper type and structure instead of using
a void pointer would be better.
next prev parent reply other threads:[~2018-10-05 21:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-02 9:26 SMSC95XX driver updates Ben Dooks
2018-10-02 9:26 ` [PATCH 1/4] usbnet: smsc95xx: add kconfig for turbo mode Ben Dooks
2018-10-02 12:46 ` Andrew Lunn
2018-10-02 9:26 ` [PATCH 2/4] usbnet: smsc95xx: align tx-buffer to word Ben Dooks
2018-10-02 13:19 ` David Laight
2018-10-02 13:35 ` Ben Dooks
2018-10-02 16:56 ` [PATCH] usbnet: smsc95xx: simplify tx_fixup code Ben Dooks
2018-10-03 13:36 ` David Laight
2018-10-03 16:25 ` Ben Dooks
2018-10-05 21:24 ` David Miller [this message]
2018-10-06 11:27 ` Ben Dooks
2018-10-06 17:28 ` David Miller
2018-10-08 8:41 ` David Laight
2018-10-04 16:53 ` [Linux-kernel] [PATCH 2/4] usbnet: smsc95xx: align tx-buffer to word Ben Hutchings
2018-10-02 9:26 ` [PATCH 3/4] usbnet: smsc95xx: check for csum being in last four bytes Ben Dooks
2018-10-02 9:45 ` Sergei Shtylyov
2018-10-04 16:55 ` [Linux-kernel] " Ben Hutchings
2018-10-02 9:26 ` [PATCH 4/4] usbnet: smsc95xx: fix rx packet alignment Ben Dooks
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