From: Lee Jones <lee.jones@linaro.org>
To: Kieran Bingham <kieran@ksquared.org.uk>
Cc: Peter Rosin <peda@axentia.se>, Wolfram Sang <wsa@the-dreams.de>,
linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
Javier Martinez Canillas <javier@osg.samsung.com>,
sameo@linux.intel.com
Subject: Re: [PATCHv6 08/11] i2c: match vendorless strings on the internal string length
Date: Tue, 1 Nov 2016 07:22:29 +0000 [thread overview]
Message-ID: <20161101072229.GP13127@dell> (raw)
In-Reply-To: <51902bcc-f5e6-ff9a-9aeb-bf7b8deeaf26@bingham.xyz>
On Mon, 31 Oct 2016, Kieran Bingham wrote:
> On 31/10/16 13:55, Peter Rosin wrote:
> > On 2016-10-26 10:53, Lee Jones wrote:
> >> On Tue, 25 Oct 2016, Kieran Bingham wrote:
> >>
> >>> If a user provides a shortened string to match a device to the sysfs i2c
> >>> interface it will match on the first string that contains that string
> >>> prefix.
> >>>
> >>> for example:
> >>> echo a 0x68 > /sys/bus/i2c/devices/i2c-2/new_device
> >>>
> >>> will match as3711, as3722, and ak8975 incorrectly.
> >>>
> >>> Signed-off-by: Kieran Bingham <kieran@bingham.xyz>
> >>
> >> Acked-by: Lee Jones <lee.jones@linaro.org>
> >>
> >>> ---
> >>> drivers/i2c/i2c-core.c | 2 +-
> >>> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
> >>> index 01bce56f733a..50c9cfdb87b7 100644
> >>> --- a/drivers/i2c/i2c-core.c
> >>> +++ b/drivers/i2c/i2c-core.c
> >>> @@ -1708,7 +1708,7 @@ i2c_of_match_device_strip_vendor(const struct of_device_id *matches,
> >>> else
> >>> name++;
> >>>
> >>> - if (!strncasecmp(client->name, name, strlen(client->name)))
> >>> + if (!strncasecmp(client->name, name, strlen(name)))
> >>> return matches;
> >>> }
> >>>
> >>
> >
> > Is that really so much better?
>
> My original thought was that it verifies 'more' of the userspace input.
> but...
>
> > With this patch
> > echo as3711CRAP 0x68 > /sys/...
> > will match as3711.
> >
> > What if there is some as37112 driver that is the real target?
>
> You're right - It looks like the only way to do this correctly is to
> match the strncasecmp and the strlen of both strings.
>
> So really we should be using sysfs_streq(). The only limitation there is
> that this original code was performing a case-insensitive compare.
>
> Lee - Where did the requirement for case insensitive matching come from
> in your original code. Is it expected to be case-insensitive from the
> I2C sysfs interface? or are dt-nodes expected to be case-sensitive?
Compatible strings are always lower-case.
> Does anyone see reason that this shouldn't be using sysfs_streq()? or do
> we need a sysfs_strcaseeq()...
... but I don't see an issue with not being case sensitive. Certainly
if it makes the logic easier/more consistent.
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
next prev parent reply other threads:[~2016-11-01 7:22 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-25 16:41 [PATCHv6 00/11] i2c: Relax mandatory I2C ID table passing Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 01/11] i2c: Add pointer dereference protection to i2c_match_id() Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 02/11] i2c: Add the ability to match device to compatible string without an of_node Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 03/11] i2c: Match using traditional OF methods, then by vendor-less compatible strings Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 04/11] i2c: Make I2C ID tables non-mandatory for DT'ed devices Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 05/11] i2c: Export i2c_match_id() for direct use by device drivers Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 06/11] i2c: Provide a temporary .probe_new() call-back type Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 07/11] i2c: match dt-style device names from sysfs interface Kieran Bingham
2016-10-26 8:55 ` Lee Jones
2016-10-25 16:41 ` [PATCHv6 08/11] i2c: match vendorless strings on the internal string length Kieran Bingham
2016-10-26 8:53 ` Lee Jones
2016-10-31 13:55 ` Peter Rosin
2016-10-31 15:01 ` Kieran Bingham
2016-11-01 7:22 ` Lee Jones [this message]
2016-10-25 16:41 ` [PATCHv6 09/11] mfd: 88pm860x: Move over to new I2C device .probe() call Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 10/11] mfd: as3722: Rid driver of superfluous I2C device ID structure Kieran Bingham
2016-10-25 16:41 ` [PATCHv6 11/11] [TESTPATCH] rtc: convert ds1307 to interim probe_new Kieran Bingham
2016-11-07 0:07 ` [PATCHv6 00/11] i2c: Relax mandatory I2C ID table passing Wolfram Sang
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