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Message-ID: <20110524063424.GC18075@gvim.org>
Date: Mon, 23 May 2011 23:34:24 -0700
From: mark gross <markgross@...gnar.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: markgross@...gnar.org, Stephen Rothwell <sfr@...b.auug.org.au>,
linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
Milton Miller <milltonm@....com>,
Simon Horman <horms@...ge.net.au>
Subject: Re: linux-next: build warning after merge of the suspend tree
On Mon, May 23, 2011 at 09:54:52PM +0200, Rafael J. Wysocki wrote:
> On Monday, May 23, 2011, mark gross wrote:
> > On Mon, May 23, 2011 at 03:06:36PM +1000, Stephen Rothwell wrote:
> > > Hi Rafael,
> > >
> > > After merging the suspend tree, today's linux-next build (i386 defconfig
> > > among others) produced this warning:
> > >
> > > kernel/pm_qos_params.c: In function 'pm_qos_power_write':
> > > kernel/pm_qos_params.c:420: warning: passing argument 3 of 'kstrtol' from incompatible pointer type
> > > include/linux/kernel.h:210: note: expected 'long int *' but argument is of type 's32 *'
> > >
> > > Intreoduced by commit 365daa955e03 ("PM: Correct PM QOS's user mode
> > > interface to work with ascii input per").
> >
> > Gah! I'm sorry about that.
> >
> > attached is a fix.
> >
> >
> > --mark
> >
> > signed-off-by:markgross <markgross@...gnar.org>
> >
> >
> >
> > From a8f0587b9ae598be5ca4c3cdda4e0ced6ca9baaf Mon Sep 17 00:00:00 2001
> > From: mgross <mgross@...8>
> > Date: Mon, 23 May 2011 07:14:09 -0700
> > Subject: [PATCH] clean up a compile time warning in the use of strict_strtol but that was
> > passing an s32 * when it should be passing a long *
> >
> > ---
> > kernel/pm_qos_params.c | 6 ++++--
> > 1 files changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/pm_qos_params.c b/kernel/pm_qos_params.c
> > index d61ecf3..dd37c56 100644
> > --- a/kernel/pm_qos_params.c
> > +++ b/kernel/pm_qos_params.c
> > @@ -405,6 +405,7 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> > size_t count, loff_t *f_pos)
> > {
> > s32 value;
> > + long safe_int;
> > int x;
> > char ascii_value[11];
> > struct pm_qos_request_list *pm_qos_req;
> > @@ -417,10 +418,11 @@ static ssize_t pm_qos_power_write(struct file *filp, const char __user *buf,
> > ascii_value[count] = 0;
> > if (copy_from_user(ascii_value, buf, count))
> > return -EFAULT;
> > - if ((x=strict_strtol(ascii_value, 16, &value)) != 0){
> > - pr_debug("%s, 0x%x, 0x%x\n",ascii_value, value, x);
> > + if ((x=strict_strtol(ascii_value, 16, &safe_int)) != 0){
> > + pr_debug("%s, 0x%lx, 0x%x\n",ascii_value, safe_int, x);
> > return -EINVAL;
> > }
> > + value = (s32) safe_int;
>
> Well, this doesn't seem quite right.
>
> > } else
> > return -EINVAL;
>
> Besides, if count == 11, there we'll write beyond ascii_value[], right?
right. That is a bug.
>
> What about the appended patch instead of your original one?
Thank you!
> Rafael
>
>
> ---
> From: mark gross <markgross@...gnar.org>
> Subject: PM: Correct PM QOS's user mode interface to work with ascii input per
>
> What is in the kernel docs. Writing a string to the ABI from user mode
> comes in 2 flavors. One with and one without a '\n' at the end. This
> change accepts both.
>
> # echo 0x12345678 > /dev/cpu_dma_latency
>
> and
>
> # echo -n 0x12345678 > /dev/cpu_dma_latency
>
> now both work.
>
> [rjw: Fixed up array bounds checking and type casting.]
>
> Signed-off-by: mark gross <markgross@...gnar.org>
> Acked-by: Simon Horman <horms@...ge.net.au>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
> kernel/pm_qos_params.c | 25 ++++++++++++++++---------
> 1 file changed, 16 insertions(+), 9 deletions(-)
>
> Index: linux-2.6/kernel/pm_qos_params.c
> ===================================================================
> --- linux-2.6.orig/kernel/pm_qos_params.c
> +++ linux-2.6/kernel/pm_qos_params.c
> @@ -40,6 +40,7 @@
> #include <linux/string.h>
> #include <linux/platform_device.h>
> #include <linux/init.h>
> +#include <linux/kernel.h>
>
> #include <linux/uaccess.h>
>
> @@ -404,24 +405,30 @@ static ssize_t pm_qos_power_write(struct
> size_t count, loff_t *f_pos)
> {
> s32 value;
> - int x;
> char ascii_value[11];
> struct pm_qos_request_list *pm_qos_req;
>
> if (count == sizeof(s32)) {
> if (copy_from_user(&value, buf, sizeof(s32)))
> return -EFAULT;
> - } else if (count == 11) { /* len('0x12345678/0') */
> - if (copy_from_user(ascii_value, buf, 11))
> + } else if (count >= 10) { /* '0x12345678' or '0x12345678\n'*/
Did you mean <= 11 here? I know that Alan Stern wanted to see the ABI
adjusted to accept shorter hex string that the full 10 char string.
FWIW I'm ok with doing that.
> + unsigned long int ulval;
> + int ret;
> +
> + count = 10;
I kind of wanted to return an error to the user if they violate the
documented format for the hex string. With this code you get a silent
truncation of the lower digits if the string is "0x123456789abcdef"
> + ascii_value[count] = 0;
> + if (copy_from_user(ascii_value, buf, count))
> return -EFAULT;
> - if (strlen(ascii_value) != 10)
> - return -EINVAL;
> - x = sscanf(ascii_value, "%x", &value);
> - if (x != 1)
> +
> + ret = strict_strtoul(ascii_value, 16, &ulval);
> + if (ret){
> + pr_debug("%s, 0x%lx, 0x%x\n", ascii_value, ulval, ret);
> return -EINVAL;
> - pr_debug("%s, %d, 0x%x\n", ascii_value, x, value);
> - } else
> + }
> + value = (s32)lower_32_bits(ulval);
This shouldn't be needed if you are constrained to a hex format of
"0x12345678" but this is more readable. lower_32_bits is a good idea.
--mark
> + } else {
> return -EINVAL;
> + }
>
> pm_qos_req = filp->private_data;
> pm_qos_update_request(pm_qos_req, value);
--
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