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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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