diff options
authorMatt Redfearn <matt.redfearn@imgtec.com>2016-10-11 12:05:15 +0100
committerSasha Levin <alexander.levin@verizon.com>2016-11-23 23:09:12 -0500
commitcc30a01ae404cbf0ef1f419cbfab2af77f3c411c (patch)
parent919224dcf46262156e9c90dd4858a2097730d074 (diff)
virtio: console: Unlock vqs while freeing buffers
[ Upstream commit 34563769e438d2881f62cf4d9badc4e589ac0ec0 ] Commit c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") added locking around the freeing of buffers in the vq. However, when free_buf() is called with can_sleep = true and rproc is enabled, it calls dma_free_coherent() directly, requiring interrupts to be enabled. Currently a WARNING is triggered due to the spin locking around free_buf, with a call stack like this: WARNING: CPU: 3 PID: 121 at ./include/linux/dma-mapping.h:433 free_buf+0x1a8/0x288 Call Trace: [<8040c538>] show_stack+0x74/0xc0 [<80757240>] dump_stack+0xd0/0x110 [<80430d98>] __warn+0xfc/0x130 [<80430ee0>] warn_slowpath_null+0x2c/0x3c [<807e7c6c>] free_buf+0x1a8/0x288 [<807ea590>] remove_port_data+0x50/0xac [<807ea6a0>] unplug_port+0xb4/0x1bc [<807ea858>] virtcons_remove+0xb0/0xfc [<807b6734>] virtio_dev_remove+0x58/0xc0 [<807f918c>] __device_release_driver+0xac/0x134 [<807f924c>] device_release_driver+0x38/0x50 [<807f7edc>] bus_remove_device+0xfc/0x130 [<807f4b74>] device_del+0x17c/0x21c [<807f4c38>] device_unregister+0x24/0x38 [<807b6b50>] unregister_virtio_device+0x28/0x44 Fix this by restructuring the loops to allow the locks to only be taken where it is necessary to protect the vqs, and release it while the buffer is being freed. Fixes: c6017e793b93 ("virtio: console: add locks around buffer removal in port unplug path") Cc: stable@vger.kernel.org Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
1 files changed, 16 insertions, 6 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 6e09c1dac2b7..2453a9f20d01 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1532,19 +1532,29 @@ static void remove_port_data(struct port *port)
/* Remove unused data this port might have received. */
+ spin_unlock_irq(&port->inbuf_lock);
/* Remove buffers we queued up for the Host to send us data in. */
- while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
- free_buf(buf, true);
- spin_unlock_irq(&port->inbuf_lock);
+ do {
+ spin_lock_irq(&port->inbuf_lock);
+ buf = virtqueue_detach_unused_buf(port->in_vq);
+ spin_unlock_irq(&port->inbuf_lock);
+ if (buf)
+ free_buf(buf, true);
+ } while (buf);
+ spin_unlock_irq(&port->outvq_lock);
/* Free pending buffers from the out-queue. */
- while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
- free_buf(buf, true);
- spin_unlock_irq(&port->outvq_lock);
+ do {
+ spin_lock_irq(&port->outvq_lock);
+ buf = virtqueue_detach_unused_buf(port->out_vq);
+ spin_unlock_irq(&port->outvq_lock);
+ if (buf)
+ free_buf(buf, true);
+ } while (buf);