[PATCH v2 3/3] virtio: implement synchronize_cbs for remaining transports
Karl Mehltretter
kmehltretter at gmail.com
Sat Sep 5 08:20:59 PDT 2026
virtio_reset_device() now calls synchronize_cbs to wait for running
callbacks. Its synchronize_rcu() fallback does not cover workqueue or
sleepable callbacks.
Add the missing hooks. UML waits for its shared IRQ; TmFIFO takes the
existing per-direction locks held around vring_interrupt(). Virtio-vdpa
uses a per-device rwlock around its callbacks, which must already be
hard-IRQ safe.
Remoteproc callbacks can run in hard-IRQ or process context, and rpmsg
callbacks can sleep, so use one SRCU domain per rproc. Enter it before
looking up the queue. Initialize it in rproc_alloc(), returning NULL if
that fails, and clean it up at final release. cleanup_srcu_struct() can
sleep, so document that rproc_put() and rproc_free() may sleep when
dropping the last reference.
These hooks wait for callbacks already running. UML, TmFIFO and
remoteproc still allow new callbacks after reset.
Suggested-by: Michael S. Tsirkin <mst at redhat.com>
Assisted-by: LLM
Signed-off-by: Karl Mehltretter <kmehltretter at gmail.com>
---
arch/um/drivers/virtio_uml.c | 10 ++++++++++
drivers/platform/mellanox/mlxbf-tmfifo.c | 14 ++++++++++++++
drivers/remoteproc/remoteproc_core.c | 10 ++++++++++
drivers/remoteproc/remoteproc_virtio.c | 20 +++++++++++++++++---
drivers/virtio/virtio_vdpa.c | 21 ++++++++++++++++++++-
include/linux/remoteproc.h | 3 +++
6 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 7425a8548141..baca6b09e9ac 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -20,6 +20,7 @@
*
* Based on Virtio MMIO driver by Pawel Moll, copyright 2011-2014, ARM Ltd.
*/
+#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
@@ -869,6 +870,14 @@ static void vu_reset(struct virtio_device *vdev)
vu_dev->status = 0;
}
+static void vu_synchronize_cbs(struct virtio_device *vdev)
+{
+ struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
+
+ if (vu_dev->irq >= 0)
+ synchronize_irq(vu_dev->irq);
+}
+
static void vu_del_vq(struct virtqueue *vq)
{
struct virtio_uml_vq_info *info = vq->priv;
@@ -1121,6 +1130,7 @@ static const struct virtio_config_ops virtio_uml_config_ops = {
.reset = vu_reset,
.find_vqs = vu_find_vqs,
.del_vqs = vu_del_vqs,
+ .synchronize_cbs = vu_synchronize_cbs,
.get_features = vu_get_features,
.finalize_features = vu_finalize_features,
.bus_name = vu_bus_name,
diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c b/drivers/platform/mellanox/mlxbf-tmfifo.c
index 3c6408581373..c260e3a1544e 100644
--- a/drivers/platform/mellanox/mlxbf-tmfifo.c
+++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
@@ -1135,6 +1135,19 @@ static void mlxbf_tmfifo_virtio_reset(struct virtio_device *vdev)
tm_vdev->status = 0;
}
+static void mlxbf_tmfifo_virtio_synchronize_cbs(struct virtio_device *vdev)
+{
+ struct mlxbf_tmfifo_vdev *tm_vdev = mlxbf_vdev_to_tmfifo(vdev);
+ struct mlxbf_tmfifo *fifo = tm_vdev->vrings[0].fifo;
+ unsigned long flags;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(fifo->spin_lock); i++) {
+ spin_lock_irqsave(&fifo->spin_lock[i], flags);
+ spin_unlock_irqrestore(&fifo->spin_lock[i], flags);
+ }
+}
+
/* Read the value of a configuration field. */
static void mlxbf_tmfifo_virtio_get(struct virtio_device *vdev,
unsigned int offset,
@@ -1179,6 +1192,7 @@ static const struct virtio_config_ops mlxbf_tmfifo_virtio_config_ops = {
.find_vqs = mlxbf_tmfifo_virtio_find_vqs,
.del_vqs = mlxbf_tmfifo_virtio_del_vqs,
.reset = mlxbf_tmfifo_virtio_reset,
+ .synchronize_cbs = mlxbf_tmfifo_virtio_synchronize_cbs,
.set_status = mlxbf_tmfifo_virtio_set_status,
.get_status = mlxbf_tmfifo_virtio_get_status,
.get = mlxbf_tmfifo_virtio_get,
diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 1ed406714849..1b139d25ab2b 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -2410,6 +2410,7 @@ static void rproc_type_release(struct device *dev)
dev_info(&rproc->dev, "releasing %s\n", rproc->name);
+ cleanup_srcu_struct(&rproc->vq_srcu);
idr_destroy(&rproc->notifyids);
if (rproc->index >= 0)
@@ -2507,6 +2508,11 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
if (!rproc)
return NULL;
+ if (init_srcu_struct(&rproc->vq_srcu)) {
+ kfree(rproc);
+ return NULL;
+ }
+
rproc->priv = &rproc[1];
rproc->auto_boot = true;
rproc->elf_class = ELFCLASSNONE;
@@ -2571,6 +2577,8 @@ EXPORT_SYMBOL(rproc_alloc);
*
* If no one holds any reference to rproc anymore, then its refcount would
* now drop to zero, and it would be freed.
+ *
+ * Context: May sleep if this drops the last reference.
*/
void rproc_free(struct rproc *rproc)
{
@@ -2586,6 +2594,8 @@ EXPORT_SYMBOL(rproc_free);
*
* If no one holds any reference to rproc anymore, then its refcount would
* now drop to zero, and it would be freed.
+ *
+ * Context: May sleep if this drops the last reference.
*/
void rproc_put(struct rproc *rproc)
{
diff --git a/drivers/remoteproc/remoteproc_virtio.c b/drivers/remoteproc/remoteproc_virtio.c
index d5e9ff045a28..ecc022e354db 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -23,6 +23,7 @@
#include <linux/err.h>
#include <linux/kref.h>
#include <linux/slab.h>
+#include <linux/srcu.h>
#include "remoteproc_internal.h"
@@ -89,14 +90,19 @@ static bool rproc_virtio_notify(struct virtqueue *vq)
irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
{
struct rproc_vring *rvring;
+ int srcu_idx;
+ irqreturn_t ret;
+
+ srcu_idx = srcu_read_lock(&rproc->vq_srcu);
dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);
rvring = idr_find(&rproc->notifyids, notifyid);
- if (!rvring || !rvring->vq)
- return IRQ_NONE;
+ ret = rvring && rvring->vq ? vring_interrupt(0, rvring->vq) : IRQ_NONE;
+
+ srcu_read_unlock(&rproc->vq_srcu, srcu_idx);
- return vring_interrupt(0, rvring->vq);
+ return ret;
}
EXPORT_SYMBOL(rproc_vq_interrupt);
@@ -242,6 +248,13 @@ static void rproc_virtio_reset(struct virtio_device *vdev)
dev_dbg(&vdev->dev, "reset !\n");
}
+static void rproc_virtio_synchronize_cbs(struct virtio_device *vdev)
+{
+ struct rproc *rproc = vdev_to_rproc(vdev);
+
+ synchronize_srcu(&rproc->vq_srcu);
+}
+
/* provide the vdev features as retrieved from the firmware */
static u64 rproc_virtio_get_features(struct virtio_device *vdev)
{
@@ -330,6 +343,7 @@ static const struct virtio_config_ops rproc_virtio_config_ops = {
.find_vqs = rproc_virtio_find_vqs,
.del_vqs = rproc_virtio_del_vqs,
.reset = rproc_virtio_reset,
+ .synchronize_cbs = rproc_virtio_synchronize_cbs,
.set_status = rproc_virtio_set_status,
.get_status = rproc_virtio_get_status,
.get = rproc_virtio_get,
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index de2af696de6c..4f9e70c1332e 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -27,6 +27,7 @@
struct virtio_vdpa_device {
struct virtio_device vdev;
struct vdpa_device *vdpa;
+ rwlock_t callback_lock;
u64 features;
};
@@ -123,8 +124,24 @@ static irqreturn_t virtio_vdpa_config_cb(void *private)
static irqreturn_t virtio_vdpa_virtqueue_cb(void *private)
{
struct virtqueue *vq = private;
+ struct virtio_vdpa_device *vd_dev;
+ unsigned long flags;
+ irqreturn_t ret;
- return vring_interrupt(0, vq);
+ vd_dev = to_virtio_vdpa_device(vq->vdev);
+ read_lock_irqsave(&vd_dev->callback_lock, flags);
+ ret = vring_interrupt(0, vq);
+ read_unlock_irqrestore(&vd_dev->callback_lock, flags);
+
+ return ret;
+}
+
+static void virtio_vdpa_synchronize_cbs(struct virtio_device *vdev)
+{
+ struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);
+
+ write_lock_irq(&vd_dev->callback_lock);
+ write_unlock_irq(&vd_dev->callback_lock);
}
static struct virtqueue *
@@ -439,6 +456,7 @@ static const struct virtio_config_ops virtio_vdpa_config_ops = {
.reset = virtio_vdpa_reset,
.find_vqs = virtio_vdpa_find_vqs,
.del_vqs = virtio_vdpa_del_vqs,
+ .synchronize_cbs = virtio_vdpa_synchronize_cbs,
.get_features = virtio_vdpa_get_features,
.finalize_features = virtio_vdpa_finalize_features,
.bus_name = virtio_vdpa_bus_name,
@@ -472,6 +490,7 @@ static int virtio_vdpa_probe(struct vdpa_device *vdpa)
vd_dev->vdev.config = &virtio_vdpa_config_ops;
vd_dev->vdev.map = vdpa->map;
vd_dev->vdpa = vdpa;
+ rwlock_init(&vd_dev->callback_lock);
vd_dev->vdev.id.device = ops->get_device_id(vdpa);
if (vd_dev->vdev.id.device == 0)
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index a44368737b39..ad6bccbdfabc 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -11,6 +11,7 @@
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
+#include <linux/srcu.h>
#include <linux/virtio.h>
#include <linux/cdev.h>
#include <linux/completion.h>
@@ -230,6 +231,7 @@ enum rproc_features {
* @rvdevs: list of remote virtio devices
* @subdevs: list of subdevices, to following the running state
* @notifyids: idr for dynamically assigning rproc-wide unique notify ids
+ * @vq_srcu: SRCU domain for virtqueue callbacks
* @index: index of this rproc device
* @attach_work: workqueue for attaching rproc
* @crash_handler: workqueue for handling a crash
@@ -276,6 +278,7 @@ struct rproc {
struct list_head rvdevs;
struct list_head subdevs;
struct idr notifyids;
+ struct srcu_struct vq_srcu;
int index;
struct work_struct attach_work;
struct work_struct crash_handler;
--
2.39.5 (Apple Git-154)
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