Hello Bjorn Helgaas,
The patch f93e71aea6c6: "Revert "PCI/ASPM: Remove
pcie_aspm_pm_state_change()"" from Jan 1, 2024 (linux-next), leads to
the following Smatch static checker warning:
drivers/pci/pcie/aspm.c:1017 pcie_aspm_pm_state_change()
warn: sleeping in atomic context
drivers/pci/pcie/aspm.c
1007 void pcie_aspm_pm_state_change(struct pci_dev *pdev)
1008 {
1009 struct pcie_link_state *link = pdev->link_state;
1010
1011 if (aspm_disabled || !link)
1012 return;
1013 /*
1014 * Devices changed PM state, we should recheck if latency
1015 * meets all functions' requirement
1016 */
--> 1017 down_read(&pci_bus_sem);
This is a revert from a patch from 2022 which was before I had written
this "sleeping in atomic" static checker thing.
1018 mutex_lock(&aspm_lock);
1019 pcie_update_aspm_capable(link->root);
1020 pcie_config_aspm_path(link);
1021 mutex_unlock(&aspm_lock);
1022 up_read(&pci_bus_sem);
1023 }
The call trees that Smatch is complaining about are:
vortex_boomerang_interrupt() <- disables preempt
-> _vortex_interrupt()
-> _boomerang_interrupt()
-> vortex_error()
-> vortex_up()
velocity_suspend() <- disables preempt
-> velocity_set_power_state()
-> pci_set_power_state()
-> pci_set_low_power_state()
-> pcie_aspm_pm_state_change()
So what Smatch is saying is the vortex_boomerang_interrupt() and
velocity_suspend() hold spin locks and then set the power state. The
call trees are quite long so I'm not really able to be sure if this is
a false positive or not... I wish this warning were more useful.
These emails are a one time thing. Just reply if it's a false positive
and I'll note it down. Otherwise feel free to ignore it.
regards,
dan carpenter
