Commit 57d86a04 authored Nov 19, 2015 by Andy Lutomirski Committed by Bjorn Helgaas Dec 03, 2015

PCI/ASPM: Make sysfs link_state_store() consistent with link_state_show()



If CONFIG_PCIEASPM_DEBUG is set, then PCI devices have a link_state
attribute.  Reading that attribute shows the state as a bit mask: 1
means L0S upstream, 2 means L0S downstream, and 4 means L1.

Oddly, writing to link_state is inconsistent and gets translated, leading
to mysterious results in which the value you store isn't comparable the
value you load back out.

Fix it by making link_state_store() match link_state_show().

[bhelgaas: Check "aspm_disabled" *before* validating input.  When
"aspm_disabled" is set, this changes the error for invalid input from
-EINVAL to -EPERM.]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

parent 1ec21837

drivers/pci/pcie/aspm.c

+5 −11

Original line number	Diff line number	Diff line
		@@ -834,21 +834,15 @@ static ssize_t link_state_store(struct device *dev,
		{
		struct pci_dev *pdev = to_pci_dev(dev);
		struct pcie_link_state link, root = pdev->link_state->root;
		u32 val, state = 0;

		if (kstrtouint(buf, 10, &val))
		return -EINVAL;
		u32 state;

		if (aspm_disabled)
		return -EPERM;
		if (n < 1 \|\| val > 3)
		return -EINVAL;

		/* Convert requested state to ASPM state */
		if (val & PCIE_LINK_STATE_L0S)
		state \|= ASPM_STATE_L0S;
		if (val & PCIE_LINK_STATE_L1)
		state \|= ASPM_STATE_L1;
		if (kstrtouint(buf, 10, &state))
		return -EINVAL;
		if ((state & ~ASPM_STATE_ALL) != 0)
		return -EINVAL;

		down_read(&pci_bus_sem);
		mutex_lock(&aspm_lock);

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