Re: [PATCH] vhost: Use mutex to protect vq_irq setup
From: Jason Wang <jasowang@redhat.com>
Date: 2020-10-29 07:22:09
Also in:
virtualization
On 2020/10/28 下午10:20, Eli Cohen wrote:
Both irq_bypass_register_producer() and irq_bypass_unregister_producer()
require process context to run. Change the call context lock from
spinlock to mutex to protect the setup process to avoid deadlocks.
Fixes: 265a0ad8731d ("vhost: introduce vhost_vring_call")
Signed-off-by: Eli Cohen <redacted>Hi Eli: During review we spot that the spinlock is not necessary. And it was already protected by vq mutex. So it was removed in this commit: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=86e182fe12ee5869022614457037097c70fe2ed1 Thanks
quoted hunk ↗ jump to hunk
--- drivers/vhost/vdpa.c | 10 +++++----- drivers/vhost/vhost.c | 6 +++--- drivers/vhost/vhost.h | 3 ++- 3 files changed, 10 insertions(+), 9 deletions(-)diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index be783592fe58..0a744f2b6e76 100644 --- a/drivers/vhost/vdpa.c +++ b/drivers/vhost/vdpa.c@@ -98,26 +98,26 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid) return; irq = ops->get_vq_irq(vdpa, qid); - spin_lock(&vq->call_ctx.ctx_lock); + mutex_lock(&vq->call_ctx.ctx_lock); irq_bypass_unregister_producer(&vq->call_ctx.producer); if (!vq->call_ctx.ctx || irq < 0) { - spin_unlock(&vq->call_ctx.ctx_lock); + mutex_unlock(&vq->call_ctx.ctx_lock); return; } vq->call_ctx.producer.token = vq->call_ctx.ctx; vq->call_ctx.producer.irq = irq; ret = irq_bypass_register_producer(&vq->call_ctx.producer); - spin_unlock(&vq->call_ctx.ctx_lock); + mutex_unlock(&vq->call_ctx.ctx_lock); } static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid) { struct vhost_virtqueue *vq = &v->vqs[qid]; - spin_lock(&vq->call_ctx.ctx_lock); + mutex_lock(&vq->call_ctx.ctx_lock); irq_bypass_unregister_producer(&vq->call_ctx.producer); - spin_unlock(&vq->call_ctx.ctx_lock); + mutex_unlock(&vq->call_ctx.ctx_lock); } static void vhost_vdpa_reset(struct vhost_vdpa *v)diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 9ad45e1d27f0..938239e11455 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -302,7 +302,7 @@ static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx) { call_ctx->ctx = NULL; memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer)); - spin_lock_init(&call_ctx->ctx_lock); + mutex_init(&call_ctx->ctx_lock); } static void vhost_vq_reset(struct vhost_dev *dev,@@ -1650,9 +1650,9 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg break; } - spin_lock(&vq->call_ctx.ctx_lock); + mutex_lock(&vq->call_ctx.ctx_lock); swap(ctx, vq->call_ctx.ctx); - spin_unlock(&vq->call_ctx.ctx_lock); + mutex_unlock(&vq->call_ctx.ctx_lock); break; case VHOST_SET_VRING_ERR: if (copy_from_user(&f, argp, sizeof f)) {diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 9032d3c2a9f4..e8855ea04205 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h@@ -64,7 +64,8 @@ enum vhost_uaddr_type { struct vhost_vring_call { struct eventfd_ctx *ctx; struct irq_bypass_producer producer; - spinlock_t ctx_lock; + /* protect vq irq setup */ + struct mutex ctx_lock; }; /* The virtqueue structure describes a queue attached to a device. */