On Wed, 28 Jan 2026 13:25:32 +0200 Tariq Toukan wrote:
From: Jiri Pirko <redacted>
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.
quoted hunk ↗ jump to hunk
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);
Would Cosmin or someone else be willing to take on co-maintainership
of this API (including reviews of other drivers using it)?
We could add a maintainers entry with:
K: devlink_shd_
So y'all get CCed.
+#include <linux/device/faux.h>
+#include <net/devlink.h>
quoted hunk ↗ jump to hunk
+/* 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) */
Why does this have to be a string? The identifier should be irrelevant,
and if something like serial number exists it can be reported in dev
info for the shared instance?
quoted hunk ↗ jump to hunk
+ struct faux_device *faux_dev; /* Related faux device */
+ refcount_t refcount; /* Reference count */
+ char priv[] __aligned(NETDEV_ALIGN); /* Driver private data */
size member annotated with __counted_by() is missing here
+};
quoted hunk ↗ jump to hunk
+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;
error labels should be named after the target not the source in new code
quoted hunk ↗ jump to hunk
+ 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;
+}
quoted hunk ↗ jump to hunk
+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;
Seems a little too defensive to check input attrs against NULL.
Let the kernel crash if someone is foolish enough..
quoted hunk ↗ jump to hunk
+ 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;
ditto
quoted hunk ↗ jump to hunk
+ 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);