[PATCH v5] ACPI: Fix acpi_evaluate_object() return value check

[Rafael J. Wysocki]

On Friday, January 24, 2014 08:25:23 AM Bjorn Helgaas wrote:
> On Fri, Jan 24, 2014 at 8:36 AM, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> > On Friday, January 24, 2014 07:54:29 AM Bjorn Helgaas wrote:
> >> On Thu, Jan 23, 2014 at 5:33 PM, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> >> > On Thursday, January 23, 2014 11:21:01 AM Bjorn Helgaas wrote:
> >> >> On Wed, Jan 22, 2014 at 8:42 PM, Yijing Wang <wangyijing at huawei.com> wrote:
> >> >> > Since acpi_evaluate_object() returns acpi_status and not plain int,
> >> >> > ACPI_FAILURE() should be used for checking its return value. Also
> >> >> > add some detailed debug info when acpi_evaluate_object() failed.
> >> >> >
> >> >> > Reviewed-by: Jani Nikula <jani.nikula at intel.com>
> >> >> > Acked-by: Bjorn Helgaas <bhelgaas at google.com>
> >> >> > Signed-off-by: Yijing Wang <wangyijing at huawei.com>
> >> >> > ---
> >> >> > v4->v5: Add some detailed debug info for acpi_evaluate_object()
> >> >> >         failure suggested by Bjorn.
> >> >> > v3->v4: Fix spell error, add Jani Nikula reviewed-by.
> >> >> > v2->v3: Fix compile error pointed out by Hanjun.
> >> >> > v1->v2: Add CC to related subsystem MAINTAINERS
> >> >> > ---
> >> >> >  drivers/gpu/drm/i915/intel_acpi.c              |   33 ++++++++++++++++-------
> >> >> >  drivers/gpu/drm/nouveau/core/subdev/mxm/base.c |   13 ++++++---
> >> >> >  drivers/gpu/drm/nouveau/nouveau_acpi.c         |   25 +++++++++++-------
> >> >> >  drivers/pci/pci-label.c                        |   10 +++++--
> >> >> >  4 files changed, 54 insertions(+), 27 deletions(-)
> >> >> >
> >> >> > diff --git a/drivers/gpu/drm/i915/intel_acpi.c b/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > index dfff090..e7b526b 100644
> >> >> > --- a/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > +++ b/drivers/gpu/drm/i915/intel_acpi.c
> >> >> > @@ -31,11 +31,13 @@ static const u8 intel_dsm_guid[] = {
> >> >> >  static int intel_dsm(acpi_handle handle, int func)
> >> >> >  {
> >> >> >         struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
> >> >> > +       struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
> >> >> >         struct acpi_object_list input;
> >> >> >         union acpi_object params[4];
> >> >> >         union acpi_object *obj;
> >> >> >         u32 result;
> >> >> > -       int ret = 0;
> >> >> > +       acpi_status status;
> >> >> > +       int ret;
> >> >> >
> >> >> >         input.count = 4;
> >> >> >         input.pointer = params;
> >> >> > @@ -50,10 +52,14 @@ static int intel_dsm(acpi_handle handle, int func)
> >> >> >         params[3].package.count = 0;
> >> >> >         params[3].package.elements = NULL;
> >> >> >
> >> >> > -       ret = acpi_evaluate_object(handle, "_DSM", &input, &output);
> >> >> > -       if (ret) {
> >> >> > -               DRM_DEBUG_DRIVER("failed to evaluate _DSM: %d\n", ret);
> >> >> > -               return ret;
> >> >> > +       status = acpi_evaluate_object(handle, "_DSM", &input, &output);
> >> >> > +       if (ACPI_FAILURE(status)) {
> >> >> > +               acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
> >> >> > +               DRM_DEBUG_DRIVER(
> >> >> > +                       "failed to evaluate _DSM for %s, exit status %u\n",
> >> >> > +                       (char *)string.pointer, (unsigned int)status);
> >> >> > +               kfree(string.pointer);
> >> >> > +               return -EINVAL;
> >> >>
> >> >> I said "too bad there isn't an *easy* way" to include more
> >> >> information.  IMHO this is too ugly and error-prone to use
> >> >> consistently.  And if you are going to add more information, why did
> >> >> you only do it for some of the calls and not others?
> >> >>
> >> >> I considered adding a %p extension to print the pathname; I don't know
> >> >> if that's worthwhile or not.  I think it would be ideal if we had a
> >> >> struct device and could use dev_info(), and then a way to connect the
> >> >> struct device with an ACPI path, like maybe a dmesg note when we
> >> >> create the struct device corresponding to an ACPI Device node.
> >> >
> >> > Well, we can generally print something like that from pci_acpi_setup().
> >> >
> >> > What about the below?  Wouldn't it generate too much output on some systems?
> >>
> >> Yeah, that probably would generate an awful lot of output.  I was just
> >> hoping to avoid treating ACPI pathnames as first-class objects.  What
> >> do you think about a %p extension?  I played with that once, but I
> >> seem to have lost the patch.
> >
> > Well, it may be worth doing.  However, that information is readily available from
> > sysfs anyway, you only need to follow the firmware_node link in the PCI device's
> > sysfs directory and read the path attribute from there.  For example, on my
> > system:
> >
> > $ cat /sys/devices/pci0000:00/0000:00:1c.4/0000:0b:00.0/firmware_node/path
> > \_SB_.PCI0.RP05.PXSX
> 
> That's perfect.  If we had a struct device, we could just use
> dev_info() for these messages.  But I have no idea how hard it would
> be to get at the struct device.

>From the pci_dev side that is trivial: use ACPI_COMPANION().  The other way
around is rather more difficult as browsing a list would be involved.

Rafael