From: Jiri Pirko <jiri@nvidia.com>
Multiple PFs may reside on the same physical chip, running a single
firmware. Some of the resources and configurations may be shared among
these PFs. Currently, there is no good object to pin the configuration
knobs on.
Introduce a shared devlink instance, instantiated upon probe of the
first PF and removed during remove of the last PF. The shared devlink
instance is backed by a faux device, as there is no PCI device related
to it. The implementation uses reference counting to manage the
lifecycle: each PF that probes calls devlink_shd_get() to get or create
the shared instance, and calls devlink_shd_put() when it removes. The
shared instance is automatically destroyed when the last PF removes.
Example:
$ devlink dev
pci/0000:08:00.0:
nested_devlink:
auxiliary/mlx5_core.eth.0
faux/mlx5_core_83013c12b77faa1a30000c82a1045c91:
nested_devlink:
pci/0000:08:00.0
pci/0000:08:00.1
auxiliary/mlx5_core.eth.0
pci/0000:08:00.1:
nested_devlink:
auxiliary/mlx5_core.eth.1
auxiliary/mlx5_core.eth.1
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
---
include/net/devlink.h | 6 ++
net/devlink/Makefile | 2 +-
net/devlink/sh_dev.c | 163 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 170 insertions(+), 1 deletion(-)
create mode 100644 net/devlink/sh_dev.c
diff --git a/include/net/devlink.h b/include/net/devlink.h
index cb839e0435a1..c453faec8ebf 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -1644,6 +1644,12 @@ void devlink_register(struct devlink *devlink);
void devlink_unregister(struct devlink *devlink);
void devlink_free(struct devlink *devlink);
+struct devlink *devlink_shd_get(const char *id,
+ const struct devlink_ops *ops,
+ size_t priv_size);
+void devlink_shd_put(struct devlink *devlink);
+void *devlink_shd_get_priv(struct devlink *devlink);
+
/**
* struct devlink_port_ops - Port operations
* @port_split: Callback used to split the port into multiple ones.
diff --git a/net/devlink/Makefile b/net/devlink/Makefile
index 000da622116a..8f2adb5e5836 100644
--- a/net/devlink/Makefile
+++ b/net/devlink/Makefile
@@ -1,4 +1,4 @@
# SPDX-License-Identifier: GPL-2.0
obj-y := core.o netlink.o netlink_gen.o dev.o port.o sb.o dpipe.o \
- resource.o param.o region.o health.o trap.o rate.o linecard.o
+ resource.o param.o region.o health.o trap.o rate.o linecard.o sh_dev.o
diff --git a/net/devlink/sh_dev.c b/net/devlink/sh_dev.c
new file mode 100644
index 000000000000..acc8d549aaae
--- /dev/null
+++ b/net/devlink/sh_dev.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved. */
+
+#include <linux/device/faux.h>
+#include <net/devlink.h>
+
+#include "devl_internal.h"
+
+static LIST_HEAD(shd_list);
+static DEFINE_MUTEX(shd_mutex); /* Protects shd_list and shd->list */
+
+/* This structure represents a shared devlink instance,
+ * there is one created per identifier (e.g., serial number).
+ */
+struct devlink_shd {
+ struct list_head list; /* Node in shd list */
+ const char *id; /* Identifier string (e.g., serial number) */
+ struct faux_device *faux_dev; /* Related faux device */
+ refcount_t refcount; /* Reference count */
+ char priv[] __aligned(NETDEV_ALIGN); /* Driver private data */
+};
+
+static struct devlink_shd *devlink_shd_lookup(const char *id)
+{
+ struct devlink_shd *shd;
+
+ list_for_each_entry(shd, &shd_list, list) {
+ if (!strcmp(shd->id, id))
+ return shd;
+ }
+
+ return NULL;
+}
+
+static struct devlink_shd *devlink_shd_create(const char *id,
+ const struct devlink_ops *ops,
+ size_t priv_size)
+{
+ struct faux_device *faux_dev;
+ struct devlink_shd *shd;
+ struct devlink *devlink;
+
+ /* Create faux device - probe will be called synchronously */
+ faux_dev = faux_device_create(id, NULL, NULL);
+ if (!faux_dev)
+ return NULL;
+
+ devlink = devlink_alloc(ops, sizeof(struct devlink_shd) + priv_size,
+ &faux_dev->dev);
+ if (!devlink)
+ goto err_devlink_alloc;
+ shd = devlink_priv(devlink);
+
+ shd->id = kstrdup(id, GFP_KERNEL);
+ if (!shd->id)
+ goto err_kstrdup_id;
+ shd->faux_dev = faux_dev;
+ refcount_set(&shd->refcount, 1);
+
+ devl_lock(devlink);
+ devl_register(devlink);
+ devl_unlock(devlink);
+
+ list_add_tail(&shd->list, &shd_list);
+
+ return shd;
+
+err_kstrdup_id:
+ devlink_free(devlink);
+
+err_devlink_alloc:
+ faux_device_destroy(faux_dev);
+ return NULL;
+}
+
+static void devlink_shd_destroy(struct devlink_shd *shd)
+{
+ struct devlink *devlink = priv_to_devlink(shd);
+ struct faux_device *faux_dev = shd->faux_dev;
+
+ list_del(&shd->list);
+ devl_lock(devlink);
+ devl_unregister(devlink);
+ devl_unlock(devlink);
+ kfree(shd->id);
+ devlink_free(devlink);
+ faux_device_destroy(faux_dev);
+}
+
+/**
+ * devlink_shd_get - Get or create a shared devlink instance
+ * @id: Identifier string (e.g., serial number) for the shared instance
+ * @ops: Devlink operations structure
+ * @priv_size: Size of private data structure
+ *
+ * Get an existing shared devlink instance identified by @id, or create
+ * a new one if it doesn't exist. The device is automatically added to
+ * the shared instance's device list. Return the devlink instance
+ * with a reference held. The caller must call devlink_shd_put() when done.
+ *
+ * Return: Pointer to the shared devlink instance on success,
+ * NULL on failure
+ */
+struct devlink *devlink_shd_get(const char *id,
+ const struct devlink_ops *ops,
+ size_t priv_size)
+{
+ struct devlink_shd *shd;
+
+ if (WARN_ON(!id || !ops))
+ return NULL;
+
+ mutex_lock(&shd_mutex);
+
+ shd = devlink_shd_lookup(id);
+ if (!shd)
+ shd = devlink_shd_create(id, ops, priv_size);
+ else
+ refcount_inc(&shd->refcount);
+
+ mutex_unlock(&shd_mutex);
+ return shd ? priv_to_devlink(shd) : NULL;
+}
+EXPORT_SYMBOL_GPL(devlink_shd_get);
+
+/**
+ * devlink_shd_put - Release a reference on a shared devlink instance
+ * @devlink: Shared devlink instance
+ *
+ * Release a reference on a shared devlink instance obtained via
+ * devlink_shd_get().
+ */
+void devlink_shd_put(struct devlink *devlink)
+{
+ struct devlink_shd *shd;
+
+ if (WARN_ON(!devlink))
+ return;
+
+ mutex_lock(&shd_mutex);
+ shd = devlink_priv(devlink);
+ if (refcount_dec_and_test(&shd->refcount))
+ devlink_shd_destroy(shd);
+ mutex_unlock(&shd_mutex);
+}
+EXPORT_SYMBOL_GPL(devlink_shd_put);
+
+/**
+ * devlink_shd_get_priv - Get private data from shared devlink instance
+ * @devlink: Devlink instance
+ *
+ * Returns a pointer to the driver's private data structure within
+ * the shared devlink instance.
+ *
+ * Return: Pointer to private data
+ */
+void *devlink_shd_get_priv(struct devlink *devlink)
+{
+ struct devlink_shd *shd = devlink_priv(devlink);
+
+ return shd->priv;
+}
+EXPORT_SYMBOL_GPL(devlink_shd_get_priv);
--
2.40.1