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SubjectRe: [PATCH] hwmon: (w83627ehf): fix broken driver init
Hi Alexander, Guenter,

On Fri, 4 Nov 2011 21:51:56 -0700, Guenter Roeck wrote:
> On Fri, Nov 04, 2011 at 08:54:10PM -0400, Alexander Beregalov wrote:
> > Commit 2265cef2 (hwmon: (w83627ehf) Properly report PECI and AMD-SI
> > sensor types) results in kernel panic if data->temp_label was not
> > initialized.
> > The problem was found with chip W83627DHG-P.
> >
> > backtrace:
> > page_fault()
> > w83627ehf_probe() 0x8e2
> >
> > w83627ehf_init_device:
> > 1837: for (i = 0; i < 3; i++) {
> > const char *label = data->temp_label[data->temp_src[i]];
> >
> > /* Digital source overrides analog type */
> > if (strncmp(label, "PECI", 4) == 0)
> > data->temp_type[i] = 6;
> >
> > movzbl 128(%r14), %edx # data->temp_src, tmp737
> > movq 144(%r13), %rax # data_32->temp_label, data_32->temp_label
> > movq $.LC18, %rsi #,
> > movl %r14d, %r15d #, i
> > subl %r13d, %r15d # D.29277, i
> > 0x928 movq (%rax,%rdx,8), %rcx #* data_32->temp_label, label
> > movl $4, %edx #,
> > movq %rcx, %rdi # label,
> > movq %rcx, -96(%rbp) #,
> > call strncmp #
> >
> > page_fault() is called at 0x928 (0x8e2+0x46).

Oops, my bad. I forgot that not all chips have temperature labels,
sorry :( Thanks for reporting so quickly!

> >
> > Add check if data->temp->label was set before use.
> >
> > Cc: Jean Delvare <khali@linux-fr.org>
> > Cc: Guenter Roeck <guenter.roeck@ericsson.com>
> > Cc: stable@kernel.org
> > Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
> > ---
> > drivers/hwmon/w83627ehf.c | 17 +++++++++--------
> > 1 files changed, 9 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/hwmon/w83627ehf.c b/drivers/hwmon/w83627ehf.c
> > index 483cb26..70f1c73 100644
> > --- a/drivers/hwmon/w83627ehf.c
> > +++ b/drivers/hwmon/w83627ehf.c
> > @@ -1835,14 +1835,15 @@ static inline void __devinit w83627ehf_init_device(struct w83627ehf_data *data,
> > diode = 0x70;
> > }
> > for (i = 0; i < 3; i++) {
> > - const char *label = data->temp_label[data->temp_src[i]];
> > -
> > - /* Digital source overrides analog type */
> > - if (strncmp(label, "PECI", 4) == 0)
> > - data->temp_type[i] = 6;
> > - else if (strncmp(label, "AMD", 3) == 0)
> > - data->temp_type[i] = 5;
> > - else if ((tmp & (0x02 << i)))
> > + if (data->temp_label) {
> > + const char *label = data->temp_label[data->temp_src[i]];
> > +
> > + /* Digital source overrides analog type */
> > + if (strncmp(label, "PECI", 4) == 0)
> > + data->temp_type[i] = 6;
> > + else if (strncmp(label, "AMD", 3) == 0)
> > + data->temp_type[i] = 5;
> > + } else if ((tmp & (0x02 << i)))
>
> Followup - something like
> const char *label = NULL;
>
> if (data->temp_label)
> label = data->temp_label[data->temp_src[i]];
>
> /* Digital source overrides analog type */
> if (label && strncmp(label, "PECI", 4) == 0)
> data->temp_type[i] = 6;
> else if (label && strncmp(label, "AMD", 3) == 0)
> data->temp_type[i] = 5;
> else if ((tmp & (0x02 << i)))
>
> should do it. I am open to better ideas...

Looks good enough to me, this is one-time initialization code, it
doesn't need to be lightning fast. Will you send a formal patch, or do
you want me to do it?

--
Jean Delvare


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