Re: [PATCH 3/7] PCI/ERR: Avoid stale error status bits on recovery failure

[Lukas Wunner <lukas@wunner.de>]

On Sun, Sep 27, 2026 at 06:31:22PM +0000, sashiko-bot@kernel.org wrote:
> > +++ b/drivers/pci/pcie/err.c
> > @@ -284,6 +284,11 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
> >  	return status;
> >  
> >  failed:
> > +	if (host->native_aer || pcie_ports_native) {
> > +		pcie_clear_device_status(dev);
> > +		pci_aer_clear_nonfatal_status(dev);
> 
> [Severity: Medium]
> When pcie_do_recovery() is invoked for a fatal error (pci_channel_io_frozen)
> and recovery fails, will this leave the fatal error bits uncleared?

Generally not.

First of all, the error status bits in the Device Status register are
cleared because in the "pci_channel_io_frozen" case, a reset is performed
unconditionally.  (They are not sticky, i.e. they do not survive a reset.)

Second, the Uncorrectable Error Status register is cleared as well because
the first thing that a driver's ->slot_reset() callback does is generally
a call to pci_restore_state(), which calls pci_aer_clear_status().

Hence explicitly clearing error status bits in the Fatal Error case has
historically been considered unnecessary.  That said, I'm not happy with
how the bits are cleared and consider this patch an interim solution.

In the long run, I would like to clear error bits immediately when a
device is examined in is_error_source() and aer_get_device_error_info(),
and I would like to clear only those bits that have been read.

Right now we may lose error bits that occur in-between reading the register
and later-on clearing it, so this is all somewhat suboptimal.

Thanks,

Lukas