Alex Williamson wrote:
> On Wed, 2014-10-29 at 20:43 +0100, Andreas Hartmann wrote:
[...]
>> Therefore, I never should need pci_save_vc_state and
>> pci_restore_vc_state. Thus, it should be ok to add "return" at the
>> beginning of each of these function, true? Then it should work.
>>
>> I tested it. It worked.
>>
>> But if I'm removing only one of these returns either in
>> pci_save_vc_state or pci_restore_vc_state, the machine hangs again.
>>
>> Therefore, there must be something odd going on in the for loops. Isn't
>> it possible to add some useful debug code to these loops to see what's
>> really going on? But the output *must* go to the actual console,
>> otherwise I can't see it!
>>
>>
>> int pci_save_vc_state(struct pci_dev *dev)
>> {
>> return 0; // must be set
>> int i;
>>
>> for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
// continue; -> works
>> int pos, ret;
>> struct pci_cap_saved_state *save_state;
// continue does not work!
--> Most probably the
struct pci_cap_saved_state *save_state;
makes the system hang! ARRAY_SIZE(vc_caps) is 3 and the whole
function is called 3 times when starting the vm.
>>
>> pos = pci_find_ext_capability(dev, vc_caps[i].id);
>> if (!pos || !pci_vc_needs_save(dev, vc_caps[i].id))
>> continue;
>
> Take the next logical step, comment out the if here and we'll statically
> take the continue. Does it still fail? If so, move the continue above
> the call to pci_find_ext_capability(), if not...
>
>>
>> save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
>
> If not, add a continue; here. Unless my pci_vc_needs_save() function is
> broken, we shouldn't be getting here anyway.
>
>> if (!save_state) {
>> dev_err(&dev->dev, "%s buffer not found in %s\n",
>> vc_caps[i].name, __func__);
>> return -ENOMEM;
>> }
>>
>> printk("%s doing %s save on %s\n", __func__, vc_caps[i].name, pci_name(dev));
>> ret = pci_vc_do_save_buffer(dev, pos, save_state, true);
>> if (ret) {
>> dev_err(&dev->dev, "%s save unsuccessful %s\n",
>> vc_caps[i].name, __func__);
>> return ret;
>> }
>> }
>>
>> return 0;
>> }
>>
>>
>> void pci_restore_vc_state(struct pci_dev *dev)
>> {
>> return; // must be set
>> int i;
>>
>> for (i = 0; i < ARRAY_SIZE(vc_caps); i++) {
>> int pos;
>> struct pci_cap_saved_state *save_state;
>>
>> pos = pci_find_ext_capability(dev, vc_caps[i].id);
>> save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id);
>
> This should never find a save_state with the pci_vc_needs_save() patch,
> so we should always take the branch below. Comment out the if (... and
> leave the continue, does the behavior change? If so, add a continue;
> line above pci_find_saved_ext_cap(), does it work? If not, add another
> continue above pci_find_ext_capability().
>
>> if (!save_state || !pos)
>> continue;
>>
>> printk("%s doing %s restore on %s\n", __func__, vc_caps[i].name, pci_name(dev));
>> pci_vc_do_save_buffer(dev, pos, save_state, false);
>> }
>> }
>
> In the "working" case with Bjorn's patch, are you actually trying to use
> the device or just testing to see if the system survives reset? You
> might at least want to run lspci -xxxx on it after reset to make sure
> it's really there. Thanks,
>
> Alex
>
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