On Tue, 24 Jun 2014, Elliott, Robert (Server Storage) wrote:
1. That will cover the .shutdown function used by mptfc.c, mptspi.c,
and mptscsih.c, but mptsas.c uses mptsas_shutdown rather than
mptscsih_shutdown. It doesn't call pci_disable_msi either.
Missed that; thanks.
2. mptscsih_suspend is another caller of mptscsih_shutdown
(although the latter does nothing right now). This is done
before calling mpt_suspend, which writes to some chip registers
to disable interrupts before calling pci_disable_msi. Adding a
pci_disable_msi call before those writes might not be safe.
Clearly more paths into this function than I investigated.
3. That mptscsih_suspend call chain will result in calling
pci_disable_msi twice, which might trigger this in
pci_disable_msi -> pci_msi_shutdown:
BUG_ON(list_empty(&dev->msi_list));
Ah, but pci_disable_msi will not even invoke pci_msi_shutdown:
if (!pci_msi_enable || !dev || !dev->msi_enabled)
return;
The same check is done in pci_msi_shutdown. If that check wasn't there,
every driver would hit that BUG_ON since most every other pci driver
disables their interrupts in their shutdown path before returning, and
then pci-driver calls it again! MPT appears to be the exception.
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