linux-kernel - Re: [PATCH] PCI/IDE: Fix duplicate stream symlink names for TSM class devices

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Message-ID: <aUs7FgdSQVUB1eux@yilunxu-OptiPlex-7050>
Date: Wed, 24 Dec 2025 09:00:06 +0800
From: Xu Yilun <yilun.xu@...ux.intel.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: linux-coco@...ts.linux.dev, linux-pci@...r.kernel.org,
	dan.j.williams@...el.com, yilun.xu@...el.com,
	baolu.lu@...ux.intel.com, zhenzhong.duan@...el.com,
	linux-kernel@...r.kernel.org, yi1.lai@...el.com
Subject: Re: [PATCH] PCI/IDE: Fix duplicate stream symlink names for TSM
 class devices

On Tue, Dec 23, 2025 at 11:31:57AM -0600, Bjorn Helgaas wrote:
> On Tue, Dec 23, 2025 at 04:56:01PM +0800, Xu Yilun wrote:
> > The symlink name streamH.R.E is unique within a specific host bridge but
> > not across the system. Error occurs e.g. when creating the first stream
> > on a second host bridge:
> > 
> > [ 1244.034755] sysfs: cannot create duplicate filename '/devices/faux/tdx_host/tsm/tsm0/stream0.0.0'
> 
> Drop timestamp because it's no relevant.  Indent quoted material two
> spaces.

Yes.

> 
> > Fix this by adding host bridge name into symlink name for TSM class
> > devices. It should be OK to change the uAPI to
> > /sys/class/tsm/tsmN/pciDDDD:BB:streamH.R.E since it's new and has few
> > users.
> 
> Looks like this adds "pciDDDD:BB:" to one name, which is described
> here and in the Documentation/ABI change.
> 
> > Internally in the IDE library, store the full name in struct pci_ide
> > so TSM symlinks can use it directly, while PCI host bridge symlinks
> > can skip the host bridge name to keep concise.
> 
> And shortens this name, but no example or doc update?  Or maybe the
> shortening just strips the "pciDDDD:BB" to preserve the existing names
> somewhere else?

The later. The shortening is the internal code change, aims to preserve
the existing name /sys/devices/pciDDDD:BB/streamH.R.E, which is
described in:

  Documentation/ABI/testing/sysfs-devices-pci-host-bridge

  What:		pciDDDD:BB/streamH.R.E

I don't want repeat the host bridge name in host bridge context.

> 
> I'm just confused about which symlinks are changing (adding
> "pciDDDD:BB") and which are being kept concise (either by staying the
> same or being shortened).

I should have clearly listed the changed & preserved symlinks. Will
improve in v2.

Thanks,
Yilun

> 
> > Fixes: a4438f06b1db ("PCI/TSM: Report active IDE streams")
> > Reported-by: Yi Lai <yi1.lai@...el.com>
> > Signed-off-by: Xu Yilun <yilun.xu@...ux.intel.com>
> > ---
> >  Documentation/ABI/testing/sysfs-class-tsm |  2 +-
> >  drivers/pci/ide.c                         | 12 +++++++++---
> >  2 files changed, 10 insertions(+), 4 deletions(-)
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-class-tsm b/Documentation/ABI/testing/sysfs-class-tsm
> > index 6fc1a5ac6da1..eff71e42c60e 100644
> > --- a/Documentation/ABI/testing/sysfs-class-tsm
> > +++ b/Documentation/ABI/testing/sysfs-class-tsm
> > @@ -8,7 +8,7 @@ Description:
> >  		link encryption and other device-security features coordinated
> >  		through a platform tsm.
> >  
> > -What:		/sys/class/tsm/tsmN/streamH.R.E
> > +What:		/sys/class/tsm/tsmN/pciDDDD:BB:streamH.R.E
> >  Contact:	linux-pci@...r.kernel.org
> >  Description:
> >  		(RO) When a host bridge has established a secure connection via
> > diff --git a/drivers/pci/ide.c b/drivers/pci/ide.c
> > index f0ef474e1a0d..db1c7423bf39 100644
> > --- a/drivers/pci/ide.c
> > +++ b/drivers/pci/ide.c
> > @@ -425,6 +425,7 @@ int pci_ide_stream_register(struct pci_ide *ide)
> >  	struct pci_host_bridge *hb = pci_find_host_bridge(pdev->bus);
> >  	struct pci_ide_stream_id __sid;
> >  	u8 ep_stream, rp_stream;
> > +	const char *short_name;
> >  	int rc;
> >  
> >  	if (ide->stream_id < 0 || ide->stream_id > U8_MAX) {
> > @@ -441,13 +442,16 @@ int pci_ide_stream_register(struct pci_ide *ide)
> >  
> >  	ep_stream = ide->partner[PCI_IDE_EP].stream_index;
> >  	rp_stream = ide->partner[PCI_IDE_RP].stream_index;
> > -	const char *name __free(kfree) = kasprintf(GFP_KERNEL, "stream%d.%d.%d",
> > +	const char *name __free(kfree) = kasprintf(GFP_KERNEL, "%s:stream%d.%d.%d",
> > +						   dev_name(&hb->dev),
> >  						   ide->host_bridge_stream,
> >  						   rp_stream, ep_stream);
> >  	if (!name)
> >  		return -ENOMEM;
> >  
> > -	rc = sysfs_create_link(&hb->dev.kobj, &pdev->dev.kobj, name);
> > +	/* Skip host bridge name in the host bridge context */
> > +	short_name = name + strlen(dev_name(&hb->dev)) + 1;
> > +	rc = sysfs_create_link(&hb->dev.kobj, &pdev->dev.kobj, short_name);
> >  	if (rc)
> >  		return rc;
> >  
> > @@ -471,8 +475,10 @@ void pci_ide_stream_unregister(struct pci_ide *ide)
> >  {
> >  	struct pci_dev *pdev = ide->pdev;
> >  	struct pci_host_bridge *hb = pci_find_host_bridge(pdev->bus);
> > +	const char *short_name;
> >  
> > -	sysfs_remove_link(&hb->dev.kobj, ide->name);
> > +	short_name = ide->name + strlen(dev_name(&hb->dev)) + 1;
> > +	sysfs_remove_link(&hb->dev.kobj, short_name);
> >  	kfree(ide->name);
> >  	ida_free(&hb->ide_stream_ids_ida, ide->stream_id);
> >  	ide->name = NULL;
> > 
> > base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8
> > -- 
> > 2.25.1
> >