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Message-Id: <20081217142241.e05fff98.akpm@linux-foundation.org>
Date: Wed, 17 Dec 2008 14:22:41 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Evgeniy Polyakov <zbr@...emap.net>
Cc: linux-kernel@...r.kernel.org, zbr@...emap.net
Subject: Re: [w1] Allow master IO commands.
On Tue, 16 Dec 2008 21:07:59 +0300
Evgeniy Polyakov <zbr@...emap.net> wrote:
> This patch allows to start IO not against already found slave devices,
> but against the bus itself, which can be used for example to probe device.
>
> ...
>
> +static int w1_process_command_master(struct w1_master *dev, struct cn_msg *req_msg,
> + struct w1_netlink_msg *req_hdr, struct w1_netlink_cmd *req_cmd)
> +{
> + int err = -EINVAL;
> + struct cn_msg *msg;
> + struct w1_netlink_msg *hdr;
> + struct w1_netlink_cmd *cmd;
> +
> + msg = kzalloc(PAGE_SIZE, GFP_KERNEL);
The use of PAGE_SIZE is odd. It's either too large (inefficient) or
too small (disaster).
Is it not practical to calculate this precisely?
> + if (!msg)
> + return -ENOMEM;
> +
> + msg->id = req_msg->id;
> + msg->seq = req_msg->seq;
> + msg->ack = 0;
> + msg->len = sizeof(struct w1_netlink_msg) + sizeof(struct w1_netlink_cmd);
> +
> + hdr = (struct w1_netlink_msg *)(msg + 1);
> + cmd = (struct w1_netlink_cmd *)(hdr + 1);
> +
> + hdr->type = W1_MASTER_CMD;
> + hdr->id = req_hdr->id;
> + hdr->len = sizeof(struct w1_netlink_cmd);
> +
> + cmd->cmd = req_cmd->cmd;
> + cmd->len = 0;
> +
> + switch (cmd->cmd) {
> + case W1_CMD_SEARCH:
checkpatch correctly points out that the body of the switch statement
should be indented one tabstop less than this.
> + case W1_CMD_ALARM_SEARCH:
> + err = w1_process_search_command(dev, msg,
> + PAGE_SIZE - msg->len - sizeof(struct cn_msg));
which would give more room for cleaning this up.
> + break;
> + case W1_CMD_READ:
> + case W1_CMD_WRITE:
> + case W1_CMD_TOUCH:
> + err = w1_process_command_io(dev, msg, hdr, cmd);
> + break;
> + default:
> + cmd->res = EINVAL;
> + cn_netlink_send(msg, 0, GFP_KERNEL);
> + break;
> + }
> +
> + kfree(msg);
> + return err;
> +}
> +
--
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