FAILED: patch "[PATCH] PCI: Allow per function PCI slots to fix slot reset on s390" failed to apply to 7.2-stable tree

FAILED: patch "[PATCH] PCI: Allow per function PCI slots to fix slot reset on s390" failed to apply to 7.2-stable tree

[gregkh]

The patch below does not apply to the 7.2-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.2.y
git checkout FETCH_HEAD
git cherry-pick -x dcc5bec09e23bbc4f9de055a11fce9937244f2c8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090354-paralyses-labored-e273@gregkh' --subject-prefix 'PATCH 7.2.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From dcc5bec09e23bbc4f9de055a11fce9937244f2c8 Mon Sep 17 00:00:00 2001
From: Farhan Ali <alifm@linux.ibm.com>
Date: Wed, 5 Aug 2026 09:55:15 -0700
Subject: [PATCH] PCI: Allow per function PCI slots to fix slot reset on s390

On s390 systems, which use a machine level hypervisor, PCI devices are
always accessed through a form of PCI pass-through which fundamentally
operates on a per PCI function granularity. This is also reflected in the
s390 PCI hotplug driver which creates hotplug slots for individual PCI
functions. Its reset_slot() function, which is a wrapper for
zpci_hot_reset_device(), thus also resets individual functions.

Currently, the pci_create_slot() assigns the same pci_slot object to
multifunction devices. This approach worked fine on s390 systems that only
exposed virtual functions as individual PCI domains to the operating
system.  Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions")
s390 supports exposing the topology of multifunction PCI devices by
grouping them in a shared PCI domain. This creates a problem when resetting
a function through the hotplug driver's slot_reset() interface.

When attempting to reset a function through the hotplug driver, the shared
slot assignment causes the wrong function to be reset instead of the
intended one. It also leaks memory as we do create a pci_slot object for
the function, but don't correctly free it in pci_slot_release().

Add a flag for struct pci_slot to allow per function PCI slots for
functions managed through a hypervisor, which exposes individual PCI
functions while retaining the topology. Since we can use all 8 bits for
slot 'number' (for ARI devices), change slot 'number' u16 to account for
special values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES.

Fixes: 44510d6fa0c0 ("s390/pci: Handling multifunctions")
Suggested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260805165518.794-3-alifm@linux.ibm.com

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 77b17b13ee61..350bae907ebf 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4897,8 +4897,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe)
 
 static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe)
 {
-	if (dev->multifunction || dev->subordinate || !dev->slot ||
-	    dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET)
+	if (dev->subordinate || !dev->slot ||
+	    dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||
+	    (dev->multifunction && !dev->slot->per_func_slot))
 		return -ENOTTY;
 
 	return pci_reset_hotplug_slot(dev->slot->hotplug, probe);
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index 42ff66461f74..897223f01f6a 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -72,6 +72,23 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
 	return bus_speed_read(slot->bus->cur_bus_speed, buf);
 }
 
+static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot)
+{
+	if (slot->per_func_slot)
+		return dev->devfn == slot->number;
+
+	return slot->number == PCI_SLOT_ALL_DEVICES ||
+		PCI_SLOT(dev->devfn) == slot->number;
+}
+
+static bool pci_slot_enabled_per_func(void)
+{
+	if (IS_ENABLED(CONFIG_S390))
+		return true;
+
+	return false;
+}
+
 static void pci_slot_release(struct kobject *kobj)
 {
 	struct pci_dev *dev;
@@ -82,8 +99,7 @@ static void pci_slot_release(struct kobject *kobj)
 
 	down_read(&pci_bus_sem);
 	list_for_each_entry(dev, &slot->bus->devices, bus_list)
-		if (slot->number == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot->number)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = NULL;
 	up_read(&pci_bus_sem);
 
@@ -187,8 +203,7 @@ void pci_dev_assign_slot(struct pci_dev *dev)
 
 	mutex_lock(&pci_slot_mutex);
 	list_for_each_entry(slot, &dev->bus->slots, list)
-		if (slot->number == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot->number)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = slot;
 	mutex_unlock(&pci_slot_mutex);
 }
@@ -299,6 +314,9 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 	slot->bus = pci_bus_get(parent);
 	slot->number = slot_nr;
 
+	if (pci_slot_enabled_per_func())
+		slot->per_func_slot = 1;
+
 	slot->kobj.kset = pci_slots_kset;
 
 	slot_name = make_slot_name(name);
@@ -319,8 +337,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 
 	down_read(&pci_bus_sem);
 	list_for_each_entry(dev, &parent->devices, bus_list)
-		if (slot_nr == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot_nr)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = slot;
 	up_read(&pci_bus_sem);
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 3824a8dd551e..8593384489db 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -79,17 +79,18 @@
  * and, if ARI Forwarding is enabled, functions may appear to be on multiple
  * devices.
  */
-#define PCI_SLOT_ALL_DEVICES	0xfe
+#define PCI_SLOT_ALL_DEVICES	0xfeff
 
 /* Used to identify a slot as a placeholder */
-#define PCI_SLOT_PLACEHOLDER	0xff
+#define PCI_SLOT_PLACEHOLDER	0xffff
 
 /* pci_slot represents a physical slot */
 struct pci_slot {
 	struct pci_bus		*bus;		/* Bus this slot is on */
 	struct list_head	list;		/* Node in list of slots */
 	struct hotplug_slot	*hotplug;	/* Hotplug info (move here) */
-	unsigned char		number;		/* Device nr, or PCI_SLOT_ALL_DEVICES */
+	u16			number;		/* Device nr, or PCI_SLOT_ALL_DEVICES */
+	unsigned int		per_func_slot:1; /* Allow per function slot */
 	struct kobject		kobj;
 };
 

[PATCH 7.2.y 1/2] PCI: Introduce PCI_SLOT_PLACEHOLDER constant for slot_nr placeholder value

[Sasha Levin]

From: Farhan Ali <alifm@linux.ibm.com>

[ Upstream commit c243e6c470c4695965cc8287767925bc1d9a7867 ]

Introduce a constant for placeholder value and update the kerneldoc for
pci_create_slot() to reference PCI_SLOT_PLACEHOLDER instead of -1
throughout. No functional change.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://patch.msgid.link/20260805165518.794-2-alifm@linux.ibm.com
Stable-dep-of: dcc5bec09e23 ("PCI: Allow per function PCI slots to fix slot reset on s390")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/pci/hotplug/pnv_php.c     |  2 +-
 drivers/pci/hotplug/rpaphp_slot.c |  2 +-
 drivers/pci/slot.c                | 21 +++++++++++----------
 include/linux/pci.h               |  3 +++
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/hotplug/pnv_php.c b/drivers/pci/hotplug/pnv_php.c
index ff92a5c301b81..37299d59f906f 100644
--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -808,7 +808,7 @@ static struct pnv_php_slot *pnv_php_alloc_slot(struct device_node *dn)
 	if (dn->child && PCI_DN(dn->child))
 		php_slot->slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
 	else
-		php_slot->slot_no = -1;   /* Placeholder slot */
+		php_slot->slot_no = PCI_SLOT_PLACEHOLDER;   /* Placeholder slot */
 
 	kref_init(&php_slot->kref);
 	php_slot->state	                = PNV_PHP_STATE_INITIALIZED;
diff --git a/drivers/pci/hotplug/rpaphp_slot.c b/drivers/pci/hotplug/rpaphp_slot.c
index 67362e5b99719..92eabf5f61b9c 100644
--- a/drivers/pci/hotplug/rpaphp_slot.c
+++ b/drivers/pci/hotplug/rpaphp_slot.c
@@ -84,7 +84,7 @@ int rpaphp_register_slot(struct slot *slot)
 	struct hotplug_slot *php_slot = &slot->hotplug_slot;
 	u32 my_index;
 	int retval;
-	int slotno = -1;
+	int slotno = PCI_SLOT_PLACEHOLDER;
 
 	dbg("%s registering slot:path[%pOF] index[%x], name[%s] pdomain[%x] type[%d]\n",
 		__func__, slot->dn, slot->index, slot->name,
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index 6d5cd37bfb1e7..42ff66461f74a 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -37,7 +37,7 @@ static const struct sysfs_ops pci_slot_sysfs_ops = {
 
 static ssize_t address_read_file(struct pci_slot *slot, char *buf)
 {
-	if (slot->number == 0xff)
+	if (slot->number == PCI_SLOT_PLACEHOLDER)
 		return sysfs_emit(buf, "%04x:%02x\n",
 				  pci_domain_nr(slot->bus),
 				  slot->bus->number);
@@ -210,7 +210,7 @@ static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 /**
  * pci_create_slot - create or increment refcount for physical PCI slot
  * @parent: struct pci_bus of parent bridge
- * @slot_nr: PCI_SLOT(pci_dev->devfn), -1 for placeholder, or
+ * @slot_nr: PCI_SLOT(pci_dev->devfn), PCI_SLOT_PLACEHOLDER for placeholder, or
  *	PCI_SLOT_ALL_DEVICES
  * @name: user visible string presented in /sys/bus/pci/slots/<name>
  * @hotplug: set if caller is hotplug driver, NULL otherwise
@@ -236,15 +236,16 @@ static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
  * a slot. There is one notable exception - pSeries (rpaphp), where the
  * @slot_nr cannot be determined until a device is actually inserted into
- * the slot. In this scenario, the caller may pass -1 for @slot_nr.
+ * the slot. In this scenario, the caller may pass PCI_SLOT_PLACEHOLDER for @slot_nr.
  *
  * The following semantics are imposed when the caller passes @slot_nr ==
- * -1. First, we no longer check for an existing %struct pci_slot, as there
- * may be many slots with @slot_nr of -1.  The other change in semantics is
- * user-visible, which is the 'address' parameter presented in sysfs will
- * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
- * %struct pci_bus and bb is the bus number. In other words, the devfn of
- * the 'placeholder' slot will not be displayed.
+ * PCI_SLOT_PLACEHOLDER. First, we no longer check for an existing %struct
+ * pci_slot, as there may be many slots with @slot_nr of
+ * PCI_SLOT_PLACEHOLDER. The other change in semantics is user-visible,
+ * which is the 'address' parameter presented in sysfs will consist solely
+ * of a dddd:bb tuple, where dddd is the PCI domain of the %struct pci_bus
+ * and bb is the bus number. In other words, the devfn of the 'placeholder'
+ * slot will not be displayed.
  *
  * Bus-wide slots:
  * For PCIe hotplug, the physical slot encompasses the entire secondary
@@ -267,7 +268,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 
 	mutex_lock(&pci_slot_mutex);
 
-	if (slot_nr == -1)
+	if (slot_nr == PCI_SLOT_PLACEHOLDER)
 		goto placeholder;
 
 	/*
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 64b308b6e61c1..b628787e9485c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -81,6 +81,9 @@
  */
 #define PCI_SLOT_ALL_DEVICES	0xfe
 
+/* Used to identify a slot as a placeholder */
+#define PCI_SLOT_PLACEHOLDER	0xff
+
 /* pci_slot represents a physical slot */
 struct pci_slot {
 	struct pci_bus		*bus;		/* Bus this slot is on */
-- 
2.53.0

[PATCH 7.2.y 2/2] PCI: Allow per function PCI slots to fix slot reset on s390

[Sasha Levin]

From: Farhan Ali <alifm@linux.ibm.com>

[ Upstream commit dcc5bec09e23bbc4f9de055a11fce9937244f2c8 ]

On s390 systems, which use a machine level hypervisor, PCI devices are
always accessed through a form of PCI pass-through which fundamentally
operates on a per PCI function granularity. This is also reflected in the
s390 PCI hotplug driver which creates hotplug slots for individual PCI
functions. Its reset_slot() function, which is a wrapper for
zpci_hot_reset_device(), thus also resets individual functions.

Currently, the pci_create_slot() assigns the same pci_slot object to
multifunction devices. This approach worked fine on s390 systems that only
exposed virtual functions as individual PCI domains to the operating
system.  Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions")
s390 supports exposing the topology of multifunction PCI devices by
grouping them in a shared PCI domain. This creates a problem when resetting
a function through the hotplug driver's slot_reset() interface.

When attempting to reset a function through the hotplug driver, the shared
slot assignment causes the wrong function to be reset instead of the
intended one. It also leaks memory as we do create a pci_slot object for
the function, but don't correctly free it in pci_slot_release().

Add a flag for struct pci_slot to allow per function PCI slots for
functions managed through a hypervisor, which exposes individual PCI
functions while retaining the topology. Since we can use all 8 bits for
slot 'number' (for ARI devices), change slot 'number' u16 to account for
special values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES.

Fixes: 44510d6fa0c0 ("s390/pci: Handling multifunctions")
Suggested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260805165518.794-3-alifm@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/pci/pci.c   |  5 +++--
 drivers/pci/slot.c  | 29 +++++++++++++++++++++++------
 include/linux/pci.h |  7 ++++---
 3 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 77b17b13ee615..350bae907ebf8 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4897,8 +4897,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe)
 
 static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe)
 {
-	if (dev->multifunction || dev->subordinate || !dev->slot ||
-	    dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET)
+	if (dev->subordinate || !dev->slot ||
+	    dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET ||
+	    (dev->multifunction && !dev->slot->per_func_slot))
 		return -ENOTTY;
 
 	return pci_reset_hotplug_slot(dev->slot->hotplug, probe);
diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
index 42ff66461f74a..897223f01f6ac 100644
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -72,6 +72,23 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
 	return bus_speed_read(slot->bus->cur_bus_speed, buf);
 }
 
+static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot)
+{
+	if (slot->per_func_slot)
+		return dev->devfn == slot->number;
+
+	return slot->number == PCI_SLOT_ALL_DEVICES ||
+		PCI_SLOT(dev->devfn) == slot->number;
+}
+
+static bool pci_slot_enabled_per_func(void)
+{
+	if (IS_ENABLED(CONFIG_S390))
+		return true;
+
+	return false;
+}
+
 static void pci_slot_release(struct kobject *kobj)
 {
 	struct pci_dev *dev;
@@ -82,8 +99,7 @@ static void pci_slot_release(struct kobject *kobj)
 
 	down_read(&pci_bus_sem);
 	list_for_each_entry(dev, &slot->bus->devices, bus_list)
-		if (slot->number == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot->number)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = NULL;
 	up_read(&pci_bus_sem);
 
@@ -187,8 +203,7 @@ void pci_dev_assign_slot(struct pci_dev *dev)
 
 	mutex_lock(&pci_slot_mutex);
 	list_for_each_entry(slot, &dev->bus->slots, list)
-		if (slot->number == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot->number)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = slot;
 	mutex_unlock(&pci_slot_mutex);
 }
@@ -299,6 +314,9 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 	slot->bus = pci_bus_get(parent);
 	slot->number = slot_nr;
 
+	if (pci_slot_enabled_per_func())
+		slot->per_func_slot = 1;
+
 	slot->kobj.kset = pci_slots_kset;
 
 	slot_name = make_slot_name(name);
@@ -319,8 +337,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 
 	down_read(&pci_bus_sem);
 	list_for_each_entry(dev, &parent->devices, bus_list)
-		if (slot_nr == PCI_SLOT_ALL_DEVICES ||
-		    PCI_SLOT(dev->devfn) == slot_nr)
+		if (pci_dev_matches_slot(dev, slot))
 			dev->slot = slot;
 	up_read(&pci_bus_sem);
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index b628787e9485c..43f80d6189a7d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -79,17 +79,18 @@
  * and, if ARI Forwarding is enabled, functions may appear to be on multiple
  * devices.
  */
-#define PCI_SLOT_ALL_DEVICES	0xfe
+#define PCI_SLOT_ALL_DEVICES	0xfeff
 
 /* Used to identify a slot as a placeholder */
-#define PCI_SLOT_PLACEHOLDER	0xff
+#define PCI_SLOT_PLACEHOLDER	0xffff
 
 /* pci_slot represents a physical slot */
 struct pci_slot {
 	struct pci_bus		*bus;		/* Bus this slot is on */
 	struct list_head	list;		/* Node in list of slots */
 	struct hotplug_slot	*hotplug;	/* Hotplug info (move here) */
-	unsigned char		number;		/* Device nr, or PCI_SLOT_ALL_DEVICES */
+	u16			number;		/* Device nr, or PCI_SLOT_ALL_DEVICES */
+	unsigned int		per_func_slot:1; /* Allow per function slot */
 	struct kobject		kobj;
 };
 
-- 
2.53.0

Patch "PCI: Introduce PCI_SLOT_PLACEHOLDER constant for slot_nr placeholder value" has been added to the 7.2-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    PCI: Introduce PCI_SLOT_PLACEHOLDER constant for slot_nr placeholder value

to the 7.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-introduce-pci_slot_placeholder-constant-for-slot_nr-placeholder-value.patch
and it can be found in the queue-7.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From stable+bounces-319225-greg=kroah.com@vger.kernel.org Wed Sep  9 14:48:10 2026
From: Sasha Levin <sashal@kernel.org>
Date: Wed,  9 Sep 2026 07:47:43 -0400
Subject: PCI: Introduce PCI_SLOT_PLACEHOLDER constant for slot_nr placeholder value
To: stable@vger.kernel.org
Cc: Farhan Ali <alifm@linux.ibm.com>, Bjorn Helgaas <bhelgaas@google.com>, Madhavan Srinivasan <maddy@linux.ibm.com>, Tyrel Datwyler <tyreld@linux.ibm.com>, linuxppc-dev@lists.ozlabs.org, Sasha Levin <sashal@kernel.org>
Message-ID: <20260909114744.2013430-1-sashal@kernel.org>

From: Farhan Ali <alifm@linux.ibm.com>

[ Upstream commit c243e6c470c4695965cc8287767925bc1d9a7867 ]

Introduce a constant for placeholder value and update the kerneldoc for
pci_create_slot() to reference PCI_SLOT_PLACEHOLDER instead of -1
throughout. No functional change.

Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Tyrel Datwyler <tyreld@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://patch.msgid.link/20260805165518.794-2-alifm@linux.ibm.com
Stable-dep-of: dcc5bec09e23 ("PCI: Allow per function PCI slots to fix slot reset on s390")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/pci/hotplug/pnv_php.c     |    2 +-
 drivers/pci/hotplug/rpaphp_slot.c |    2 +-
 drivers/pci/slot.c                |   21 +++++++++++----------
 include/linux/pci.h               |    3 +++
 4 files changed, 16 insertions(+), 12 deletions(-)

--- a/drivers/pci/hotplug/pnv_php.c
+++ b/drivers/pci/hotplug/pnv_php.c
@@ -808,7 +808,7 @@ static struct pnv_php_slot *pnv_php_allo
 	if (dn->child && PCI_DN(dn->child))
 		php_slot->slot_no = PCI_SLOT(PCI_DN(dn->child)->devfn);
 	else
-		php_slot->slot_no = -1;   /* Placeholder slot */
+		php_slot->slot_no = PCI_SLOT_PLACEHOLDER;   /* Placeholder slot */
 
 	kref_init(&php_slot->kref);
 	php_slot->state	                = PNV_PHP_STATE_INITIALIZED;
--- a/drivers/pci/hotplug/rpaphp_slot.c
+++ b/drivers/pci/hotplug/rpaphp_slot.c
@@ -84,7 +84,7 @@ int rpaphp_register_slot(struct slot *sl
 	struct hotplug_slot *php_slot = &slot->hotplug_slot;
 	u32 my_index;
 	int retval;
-	int slotno = -1;
+	int slotno = PCI_SLOT_PLACEHOLDER;
 
 	dbg("%s registering slot:path[%pOF] index[%x], name[%s] pdomain[%x] type[%d]\n",
 		__func__, slot->dn, slot->index, slot->name,
--- a/drivers/pci/slot.c
+++ b/drivers/pci/slot.c
@@ -37,7 +37,7 @@ static const struct sysfs_ops pci_slot_s
 
 static ssize_t address_read_file(struct pci_slot *slot, char *buf)
 {
-	if (slot->number == 0xff)
+	if (slot->number == PCI_SLOT_PLACEHOLDER)
 		return sysfs_emit(buf, "%04x:%02x\n",
 				  pci_domain_nr(slot->bus),
 				  slot->bus->number);
@@ -210,7 +210,7 @@ static struct pci_slot *get_slot(struct
 /**
  * pci_create_slot - create or increment refcount for physical PCI slot
  * @parent: struct pci_bus of parent bridge
- * @slot_nr: PCI_SLOT(pci_dev->devfn), -1 for placeholder, or
+ * @slot_nr: PCI_SLOT(pci_dev->devfn), PCI_SLOT_PLACEHOLDER for placeholder, or
  *	PCI_SLOT_ALL_DEVICES
  * @name: user visible string presented in /sys/bus/pci/slots/<name>
  * @hotplug: set if caller is hotplug driver, NULL otherwise
@@ -236,15 +236,16 @@ static struct pci_slot *get_slot(struct
  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
  * a slot. There is one notable exception - pSeries (rpaphp), where the
  * @slot_nr cannot be determined until a device is actually inserted into
- * the slot. In this scenario, the caller may pass -1 for @slot_nr.
+ * the slot. In this scenario, the caller may pass PCI_SLOT_PLACEHOLDER for @slot_nr.
  *
  * The following semantics are imposed when the caller passes @slot_nr ==
- * -1. First, we no longer check for an existing %struct pci_slot, as there
- * may be many slots with @slot_nr of -1.  The other change in semantics is
- * user-visible, which is the 'address' parameter presented in sysfs will
- * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
- * %struct pci_bus and bb is the bus number. In other words, the devfn of
- * the 'placeholder' slot will not be displayed.
+ * PCI_SLOT_PLACEHOLDER. First, we no longer check for an existing %struct
+ * pci_slot, as there may be many slots with @slot_nr of
+ * PCI_SLOT_PLACEHOLDER. The other change in semantics is user-visible,
+ * which is the 'address' parameter presented in sysfs will consist solely
+ * of a dddd:bb tuple, where dddd is the PCI domain of the %struct pci_bus
+ * and bb is the bus number. In other words, the devfn of the 'placeholder'
+ * slot will not be displayed.
  *
  * Bus-wide slots:
  * For PCIe hotplug, the physical slot encompasses the entire secondary
@@ -267,7 +268,7 @@ struct pci_slot *pci_create_slot(struct
 
 	mutex_lock(&pci_slot_mutex);
 
-	if (slot_nr == -1)
+	if (slot_nr == PCI_SLOT_PLACEHOLDER)
 		goto placeholder;
 
 	/*
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -81,6 +81,9 @@
  */
 #define PCI_SLOT_ALL_DEVICES	0xfe
 
+/* Used to identify a slot as a placeholder */
+#define PCI_SLOT_PLACEHOLDER	0xff
+
 /* pci_slot represents a physical slot */
 struct pci_slot {
 	struct pci_bus		*bus;		/* Bus this slot is on */


Patches currently in stable-queue which might be from sashal@kernel.org are

queue-7.2/bpf-factor-stackid_init-function-from-__bpf_get_stackid.patch
queue-7.2/kvm-x86-mmu-use-split-zap-all-fast-helpers-when-invalidating-memslot.patch
queue-7.2/net-skbuff-don-t-skb_tx_error-the-source-skb-in-skb_.patch
queue-7.2/remoteproc-qcom-pas-guard-dtb-metadata-release-with-dtb_pas_id-check.patch
queue-7.2/zram-move-lockmap-to-be-per-zram-instead-per-table.patch
queue-7.2/usb-gadget-ffs-fix-mm-lifetime-handling.patch
queue-7.2/bpf-disable-preemption-in-bpf_get_stackid.patch
queue-7.2/acpi-battery-protect-all-properties-with-a-separated-mutex.patch
queue-7.2/pci-allow-per-function-pci-slots-to-fix-slot-reset-on-s390.patch
queue-7.2/bpf-factor-stackid_new_bucket-from-__bpf_get_stackid.patch
queue-7.2/bpf-factor-stackid_fastpath-function-from-__bpf_get_stackid.patch
queue-7.2/kvm-x86-mmu-fold-kvm_mmu_zap_memslot-into-kvm_arch_flush_shadow_memslot.patch
queue-7.2/kvm-x86-mmu-split-kvm_mmu_zap_all_fast-into-front-and-back-halves.patch
queue-7.2/nfsd-prevent-client-use-after-free-during-blocked-lock-reaping.patch
queue-7.2/nfsd-prevent-client-use-after-free-during-close_lru-reaping.patch
queue-7.2/nfsd-annotate-caller-preconditions-for-the-state-table-walkers.patch
queue-7.2/kvm-sev-forcefully-invalidate-snp-vmsa-if-its-backing-gmem-page-is-zapped.patch
queue-7.2/nfsd-guard-admin-state-revocation-walks-with-nfsd_net_up.patch
queue-7.2/power-supply-ab8500_fg-fix-use-after-free-on-remove.patch
queue-7.2/ceph-properly-decrypt-filenames-in-vmalloc-buffers.patch
queue-7.2/zram-fix-slot-lock-bit-position-on-big-endian-64-bit.patch
queue-7.2/pci-introduce-pci_slot_placeholder-constant-for-slot_nr-placeholder-value.patch
queue-7.2/nfsd-prevent-client-use-after-free-during-export-state-revocation.patch
queue-7.2/hid-sony-clean-up-device-list-on-probe-failure.patch
queue-7.2/bpf-use-stack-id-functions-instead-of-__bpf_get_stackid.patch
queue-7.2/rpcrdma-arm-rn_done-before-publishing-the-notification.patch
queue-7.2/power-supply-ab8500_fg-remove-redundant-dev_err-dev_err_probe.patch
queue-7.2/usb-gadget-f_fs-fix-use-after-free-in-aio-error-path.patch
queue-7.2/acpi-battery-use-kstrtoul-over-sscanf-lu-n.patch
queue-7.2/mm-page_alloc-don-t-spin_trylock-in-nmi-on-up.patch
queue-7.2/hid-sony-use-guard-and-scoped_guard.patch
queue-7.2/nfsd-consolidate-the-revocation-path-client-unpin.patch