Re: [PATCH v3 3/3] s390/pci: Enable CONTEXT_ANALYSIS

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:

Pre-existing issues:
- [High] Missing lock acquisition in zpci_remove_reserved_devices() leading to lockdep failure and state corruption.
- [High] Race condition in zpci_event_avail_new_device() exposing an unlocked device to concurrent state changes.
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--- Patch [3]: [PATCH v3 3/3] s390/pci: Enable CONTEXT_ANALYSIS ---
commit f14ecb575360924ecbbf3801f2b0b0e2ff3a2eeb
Author: Heiko Carstens <[email protected]>

s390/pci: Enable CONTEXT_ANALYSIS

This commit enables CONTEXT_ANALYSIS in the s390 PCI Makefile since the
code now compiles without warnings.

> diff --git a/arch/s390/pci/Makefile b/arch/s390/pci/Makefile
> index 1810e0944a4ed..b8be1316491b8 100644
> --- a/arch/s390/pci/Makefile
> +++ b/arch/s390/pci/Makefile
> @@ -3,6 +3,8 @@
>  # Makefile for the s390 PCI subsystem.
>  #
>  
> +CONTEXT_ANALYSIS := y
> +

[Severity: High]
This is a pre-existing issue and was not introduced by the patch under
review, but since context analysis is being enabled to catch locking issues,
I noticed a missing lock acquisition that it might not be catching.

In arch/s390/pci/pci.c:zpci_remove_reserved_devices():

	list_for_each_entry_safe(zdev, tmp, &remove, entry)
		zpci_device_reserved(zdev);

The function zpci_device_reserved() unconditionally asserts
lockdep_assert_held(&zdev->state_lock). Will calling it here without
holding zdev->state_lock lead to a lockdep failure or state corruption
if accessed concurrently by sysfs or event handlers?


[Severity: High]
This is also a pre-existing issue not introduced by the patch under
review, but there might be a race condition exposed here as well.

In arch/s390/pci/pci_event.c:zpci_event_avail_new_device():

	if (zpci_add_device(zdev)) {
		kfree(zdev);
		break;
	}
	zpci_scan_configured_device(zdev, ccdf->fh);

Once zpci_add_device() publishes the device globally, can concurrent
threads acquire zdev->state_lock and deconfigure the device while
zpci_scan_configured_device() is still running unlocked?

>  obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_clp.o \
>  			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
>  			   pci_bus.o pci_kvm_hook.o pci_report.o pci_fixup.o

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Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=3