On 01/16, Stephen Hemminger wrote:
>On Wed, 16 Jan 2019 15:48:36 +0800
>Ye Xiaolong <xiaolong...@intel.com> wrote:
>
>> Hi, Stephen
>>
>> On 01/15, Stephen Hemminger wrote:
>> >On Wed, 16 Jan 2019 08:34:52 +0800
>> >Xiaolong Ye <xiaolong...@intel.com> wrote:
>> >
>> >> The comment for igbuio_pci_irqhandler is out of date as the code evolves,
>> >> remove it to avoid misleading.
>> >>
>> >> Signed-off-by: Xiaolong Ye <xiaolong...@intel.com>
>> >> ---
>> >> kernel/linux/igb_uio/igb_uio.c | 4 ----
>> >> 1 file changed, 4 deletions(-)
>> >>
>> >> diff --git a/kernel/linux/igb_uio/igb_uio.c
>> >> b/kernel/linux/igb_uio/igb_uio.c
>> >> index 3cf394bdf..d6ac51e79 100644
>> >> --- a/kernel/linux/igb_uio/igb_uio.c
>> >> +++ b/kernel/linux/igb_uio/igb_uio.c
>> >> @@ -185,10 +185,6 @@ igbuio_pci_irqcontrol(struct uio_info *info, s32
>> >> irq_state)
>> >> return 0;
>> >> }
>> >>
>> >> -/**
>> >> - * This is interrupt handler which will check if the interrupt is for
>> >> the right device.
>> >> - * If yes, disable it here and will be enable later.
>> >> - */
>> >> static irqreturn_t
>> >> igbuio_pci_irqhandler(int irq, void *dev_id)
>> >> {
>> >
>> >The comment is partially correct; if you look at the legacy case.
>> >
>> >Maybe better to move the comment to pci_check_and_mask_intx in compat.h?
>> >I see there is another incorrect comment there.
>> >
>>
>> As I tried to understand pci_check_and_mask_intx behavior, I noticed that it
>> was introduced by commit 399a3f0d ("igb_uio: fix IRQ mode handling"), and it
>> was derived from igbuio_set_interrupt_mask, however there were two parameters
>> in igbuio_set_interrupt_mask as below:
>>
>> static int
>> igbuio_set_interrupt_mask(struct rte_uio_pci_dev *udev, int32_t state)
>>
>> while the pci_check_and_mask_intx only has 1 parameter,
>>
>> static bool pci_check_and_mask_intx(struct pci_dev *pdev)
>>
>> but in its function body it still use the "state" accorrding to commit
>> 399a3f0d
>>
>> +static bool pci_check_and_mask_intx(struct pci_dev *pdev)
>> {
>> - /* Some function names changes between 3.2.0 and 3.3.0... */
>> -#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 3, 0)
>> - pci_unblock_user_cfg_access(pdev);
>> -#else
>> - pci_cfg_access_unlock(pdev);
>> -#endif
>> + bool pending;
>> + uint32_t status;
>> +
>> + pci_block_user_cfg_access(dev);
>> + pci_read_config_dword(pdev, PCI_COMMAND, &status);
>> +
>> + /* interrupt is not ours, goes to out */
>> + pending = (((status >> 16) & PCI_STATUS_INTERRUPT) != 0);
>> + if (pending) {
>> + uint16_t old, new;
>> +
>> + old = status;
>> + if (state != 0) <=========================== state still in
>> use
>> + new = old & (~PCI_COMMAND_INTX_DISABLE);
>> + else
>> + new = old | PCI_COMMAND_INTX_DISABLE;
>> +
>> + if (old != new)
>> + pci_write_config_word(pdev, PCI_COMMAND, new);
>> + }
>> + pci_unblock_user_cfg_access(dev);
>> +
>> + return pending;
>>
>> and later this was fixed as a typo in commit 5b2f8137 ("igb_uio: fix typos
>> for
>> kernel older than 3.3") which seems not correct.
>>
>> old = status;
>> - if (state != 0)
>> + if (status != 0)
>>
>> I feel like that pci_check_and_mask_intx still needs two parameters from code
>> point of view, please correct me if I was wrong or miss anything, or you
>> think
>> it's sensible, I'll cook a patch for it.
>>
>> Thanks,
>> Xiaolong
>
>This code is copy of upstream kernel function, you should look at that.
Thanks, just checked the kernel version of pci_check_and_mask_intx, and it is a
wrap of pci_check_and_set_intx_mask(pdev, true).
bool pci_check_and_mask_intx(struct pci_dev *dev)
{
return pci_check_and_set_intx_mask(dev, true);
}
static bool pci_check_and_set_intx_mask(struct pci_dev *dev, bool mask)
{
struct pci_bus *bus = dev->bus;
...
origcmd = cmd_status_dword;
newcmd = origcmd & ~PCI_COMMAND_INTX_DISABLE;
if (mask)
newcmd |= PCI_COMMAND_INTX_DISABLE;
if (newcmd != origcmd)
bus->ops->write(bus, dev->devfn, PCI_COMMAND, 2,
newcmd);
done:
raw_spin_unlock_irqrestore(&pci_lock, flags);
return mask_updated;
}
if mask is set to ture, PCI_COMMAND_INTX_DISABLE will be set in newcmd.
And current dpdk version doesn't align with it:
static bool pci_check_and_mask_intx(struct pci_dev *pdev)
{
bool pending;
uint32_t status;
pci_block_user_cfg_access(pdev);
pci_read_config_dword(pdev, PCI_COMMAND, &status);
/* interrupt is not ours, goes to out */
pending = (((status >> 16) & PCI_STATUS_INTERRUPT) != 0);
if (pending) {
uint16_t old, new;
old = status;
if (status != 0)
new = old & (~PCI_COMMAND_INTX_DISABLE);
else
new = old | PCI_COMMAND_INTX_DISABLE;
if (old != new)
pci_write_config_word(pdev, PCI_COMMAND, new);
}
pci_unblock_user_cfg_access(pdev);
return pending;
}
In this code, if the interrupt is triggered by this device, both pending and
status will not be 0, so the PCI_COMMAND_INTX_DISABLE will be cleared for new.
To align the behavior with upstream kernel, we may need change like:
diff --git a/kernel/linux/igb_uio/compat.h b/kernel/linux/igb_uio/compat.h
index 8dbb896ae..a78c97f91 100644
--- a/kernel/linux/igb_uio/compat.h
+++ b/kernel/linux/igb_uio/compat.h
@@ -107,10 +107,7 @@ static bool pci_check_and_mask_intx(struct pci_dev *pdev)
uint16_t old, new;
old = status;
- if (status != 0)
- new = old & (~PCI_COMMAND_INTX_DISABLE);
- else
- new = old | PCI_COMMAND_INTX_DISABLE;
+ new = old | PCI_COMMAND_INTX_DISABLE;
if (old != new)
pci_write_config_word(pdev, PCI_COMMAND, new);
Please correct me if I was wrong.
Thanks,
Xiaolong
