The patch below does not apply to the 5.15-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.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From af9fb41ed315ce95f659f0b10b4d59a71975381d Mon Sep 17 00:00:00 2001 From: Johannes Berg johannes.berg@intel.com Date: Tue, 17 May 2022 22:52:50 +0200 Subject: [PATCH] um: virtio_uml: Fix broken device handling in time-travel
If a device implementation crashes, virtio_uml will mark it as dead by calling virtio_break_device() and scheduling the work that will remove it.
This still seems like the right thing to do, but it's done directly while reading the message, and if time-travel is used, this is in the time-travel handler, outside of the normal Linux machinery. Therefore, we cannot acquire locks or do normal "linux-y" things because e.g. lockdep will be confused about the context.
Move handling this situation out of the read function and into the actual IRQ handler and response handling instead, so that in the case of time-travel we don't call it in the wrong context.
Chances are the system will still crash immediately, since the device implementation crashing may also cause the time- travel controller to go down, but at least all of that now happens without strange warnings from lockdep.
Fixes: c8177aba37ca ("um: time-travel: rework interrupt handling in ext mode") Cc: stable@vger.kernel.org Signed-off-by: Johannes Berg johannes.berg@intel.com Signed-off-by: Richard Weinberger richard@nod.at
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c index ba562d68dc04..82ff3785bf69 100644 --- a/arch/um/drivers/virtio_uml.c +++ b/arch/um/drivers/virtio_uml.c @@ -63,6 +63,7 @@ struct virtio_uml_device {
u8 config_changed_irq:1; uint64_t vq_irq_vq_map; + int recv_rc; };
struct virtio_uml_vq_info { @@ -148,14 +149,6 @@ static int vhost_user_recv(struct virtio_uml_device *vu_dev,
rc = vhost_user_recv_header(fd, msg);
- if (rc == -ECONNRESET && vu_dev->registered) { - struct virtio_uml_platform_data *pdata; - - pdata = vu_dev->pdata; - - virtio_break_device(&vu_dev->vdev); - schedule_work(&pdata->conn_broken_wk); - } if (rc) return rc; size = msg->header.size; @@ -164,6 +157,21 @@ static int vhost_user_recv(struct virtio_uml_device *vu_dev, return full_read(fd, &msg->payload, size, false); }
+static void vhost_user_check_reset(struct virtio_uml_device *vu_dev, + int rc) +{ + struct virtio_uml_platform_data *pdata = vu_dev->pdata; + + if (rc != -ECONNRESET) + return; + + if (!vu_dev->registered) + return; + + virtio_break_device(&vu_dev->vdev); + schedule_work(&pdata->conn_broken_wk); +} + static int vhost_user_recv_resp(struct virtio_uml_device *vu_dev, struct vhost_user_msg *msg, size_t max_payload_size) @@ -171,8 +179,10 @@ static int vhost_user_recv_resp(struct virtio_uml_device *vu_dev, int rc = vhost_user_recv(vu_dev, vu_dev->sock, msg, max_payload_size, true);
- if (rc) + if (rc) { + vhost_user_check_reset(vu_dev, rc); return rc; + }
if (msg->header.flags != (VHOST_USER_FLAG_REPLY | VHOST_USER_VERSION)) return -EPROTO; @@ -369,6 +379,7 @@ static irqreturn_t vu_req_read_message(struct virtio_uml_device *vu_dev, sizeof(msg.msg.payload) + sizeof(msg.extra_payload));
+ vu_dev->recv_rc = rc; if (rc) return IRQ_NONE;
@@ -412,7 +423,9 @@ static irqreturn_t vu_req_interrupt(int irq, void *data) if (!um_irq_timetravel_handler_used()) ret = vu_req_read_message(vu_dev, NULL);
- if (vu_dev->vq_irq_vq_map) { + if (vu_dev->recv_rc) { + vhost_user_check_reset(vu_dev, vu_dev->recv_rc); + } else if (vu_dev->vq_irq_vq_map) { struct virtqueue *vq;
virtio_device_for_each_vq((&vu_dev->vdev), vq) {