linux-kernel - Re: [PATCH] [net/irda]: new Blackfin on-chip SIR IrDA driver

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Message-ID: <7d86d44a0903112255m34392231ne0cd04196e33f1b2@mail.gmail.com>
Date:	Thu, 12 Mar 2009 13:55:53 +0800
From:	graff yang <graff.yang@...il.com>
To:	Mike Frysinger <vapier.adi@...il.com>
Cc:	gyang <graf.yang@...log.com>, samuel@...tiz.org,
	irda-users@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
	cooloney@...nel.org
Subject: Re: [PATCH] [net/irda]: new Blackfin on-chip SIR IrDA driver

On Thu, Mar 12, 2009 at 12:59 PM, Mike Frysinger <vapier.adi@...il.com> wrote:
> On Thu, Mar 12, 2009 at 00:48, gyang wrote:
>> On Thu, 2009-03-12 at 00:34 -0400, Mike Frysinger wrote:
>>> On Thu, Mar 12, 2009 at 00:30, gyang wrote:
>>> > On Thu, 2009-03-12 at 00:23 -0400, Mike Frysinger wrote:
>>> >> On Thu, Mar 12, 2009 at 00:17, gyang wrote:
>>> >> > On Wed, 2009-03-11 at 06:43 -0400, Mike Frysinger wrote:
>>> >> >> On Wed, Mar 11, 2009 at 05:56, graff yang wrote:
>>> >> >> > On Wed, Mar 11, 2009 at 3:57 PM, Mike Frysinger wrote:
>>> >> >> >> On Wed, Mar 11, 2009 at 03:29,  <graff.yang@...il.com> wrote:
>>> >> >> >>> +static int __devinit bfin_sir_probe(struct platform_device *pdev)
>>> >> >> >>> +{
>>> >> >> >>> +       struct net_device *dev;
>>> >> >> >>> +       struct bfin_sir_self *self;
>>> >> >> >>> +       unsigned int baudrate_mask;
>>> >> >> >>> +       struct bfin_sir_port *sir_port;
>>> >> >> >>> +       int err;
>>> >> >> >>> +
>>> >> >> >>> +       err = peripheral_request_list(per[pdev->id], DRIVER_NAME);
>>> >> >> >>
>>> >> >> >> what if pdev->id is set to 12512 ?
>>> >> >> >
>>> >> >> > The pdev->id is defined in board files, for example, uart0 should be 0.
>>> >> >>
>>> >> >> so ?  what's to stop the user from setting it to 12415 ?  the driver
>>> >> >> must sanity check these things.  you can never assume platform dev
>>> >> >> resources always have valid pointers and valid values.
>>> >> >
>>> >> > How about to limit the pdev->id to be 0,1,2,3 ?
>>> >> > I can extend the per to be
>>> >> > static const unsigned short per[][4] = {
>>> >> >        {P_UART0_RX, P_UART0_TX, 0, 0},
>>> >> >        {P_UART1_RX, P_UART1_TX, 0, 1},
>>> >> >        {P_UART2_RX, P_UART2_TX, 0, 2},
>>> >> >        {P_UART3_RX, P_UART3_TX, 0, 3},
>>> >> > };
>>> >> >
>>> >> > then check (pdev->id >= 0 && pdev->id < ARRAY_SIZE(per) &&
>>> >> > per[pdev->id][3] == pdev->id)
>>> >>
>>> >> the last check is redundant.  the first two should be added.
>>> >
>>> > I'm afraid of some cases such as uart0 uses id 1, will cause driver not
>>> > work, and not any warning message.
>>>
>>> then the call to peripheral request would fail as expected
>>
>> For example, user want to enable irda on uart2 for bf548, he use id 0
>> for uart2. In these case, peripheral request may not fail, but driver
>> not work.
>
> the id is wrong then.  if they want uart2, then they should use id 2.
> -mike
>

Such wrong case may existed for common users, and should be
prohibited. Driver need make sanity check to prevent it.

-- 
-Graff
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