Re: [PATCH v11 01/19] PCI/P2PDMA: Honor device-specific ACS redirection

[Leon Romanovsky <leon@kernel.org>]

On Tue, Oct 13, 2026 at 02:44:37PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] pci/p2pdma: deadlock in calc_map_type_and_dist() calling xa_store() from softirq
> --
> 
> commit 6120f97b22446453f3e4fa09135e1a44135ecfe8
> Author: Leon Romanovsky <leon@kernel.org>
> 
> PCI/P2PDMA: Honor device-specific ACS redirection
> 
> This commit updates PCI P2PDMA to respect device-specific ACS redirection
> quirks for switches and ports that redirect peer-to-peer traffic without a
> standard ACS capability. It queries quirks to set Request and Completion
> Redirect flags and modifies how affected ports are warned about.
> 
> > diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> > index 45260423dfb09..ba94b0f339285 100644
> > --- a/drivers/pci/p2pdma.c
> > +++ b/drivers/pci/p2pdma.c
> [ ... ]
> > @@ -782,15 +867,8 @@ calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
> >  		goto done;
> >  	}
> >  
> > -	if (verbose) {
> > -		/* Drop the final semicolon; the list is not empty here */
> > -		if (!seq_buf_has_overflowed(&acs_list))
> > -			acs_list.buffer[acs_list.len - 1] = '\0';
> > -		pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
> > -			 pci_name(provider));
> > -		pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
> > -			 seq_buf_str(&acs_list));
> > -	}
> > +	if (verbose)
> > +		pci_p2pdma_warn_redir(client, provider, &acs_list, &quirk_list);
> >  
> >  map_through_host_bridge:
> >  	if (!cpu_supports_p2pdma() &&
> 
> [Severity: High]
> Does calling xa_store() further down in this function risk a deadlock?

Not in the current code base, I failed to find any reliable path for it.

Thanks