git: 7a0c23da4eaa - main - vmm: Destroy character devices synchronously.

The branch main has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=7a0c23da4eaa63f00e53aa18f3ab1f2bb32f593a

commit 7a0c23da4eaa63f00e53aa18f3ab1f2bb32f593a
Author:     John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2022-05-20 16:53:43 +0000
Commit:     John Baldwin <jhb@FreeBSD.org>
CommitDate: 2022-05-20 16:53:43 +0000

    vmm: Destroy character devices synchronously.
    
    This fixes a userland race where bhyveload or bhyve can fail to reuse
    a VM name after bhyvectl --destroy has returned.
    
    Reported by:    Michael Dexter
    Reviewed by:    markj
    Differential Revision:  https://reviews.freebsd.org/D35186
---
 sys/amd64/vmm/vmm_dev.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/sys/amd64/vmm/vmm_dev.c b/sys/amd64/vmm/vmm_dev.c
index f5973ef5b6a7..db8563c91830 100644
--- a/sys/amd64/vmm/vmm_dev.c
+++ b/sys/amd64/vmm/vmm_dev.c
@@ -1052,10 +1052,7 @@ sysctl_vmm_destroy(SYSCTL_HANDLER_ARGS)
 	}
 
 	/*
-	 * The 'cdev' will be destroyed asynchronously when 'si_threadcount'
-	 * goes down to 0 so we should not do it again in the callback.
-	 *
-	 * Setting 'sc->cdev' to NULL is also used to indicate that the VM
+	 * Setting 'sc->cdev' to NULL is used to indicate that the VM
 	 * is scheduled for destruction.
 	 */
 	cdev = sc->cdev;
@@ -1063,21 +1060,19 @@ sysctl_vmm_destroy(SYSCTL_HANDLER_ARGS)
 	mtx_unlock(&vmmdev_mtx);
 
 	/*
-	 * Schedule all cdevs to be destroyed:
+	 * Destroy all cdevs:
 	 *
 	 * - any new operations on the 'cdev' will return an error (ENXIO).
 	 *
-	 * - when the 'si_threadcount' dwindles down to zero the 'cdev' will
-	 *   be destroyed and the callback will be invoked in a taskqueue
-	 *   context.
-	 *
 	 * - the 'devmem' cdevs are destroyed before the virtual machine 'cdev'
 	 */
 	SLIST_FOREACH(dsc, &sc->devmem, link) {
 		KASSERT(dsc->cdev != NULL, ("devmem cdev already destroyed"));
-		destroy_dev_sched_cb(dsc->cdev, devmem_destroy, dsc);
+		destroy_dev(dsc->cdev);
+		devmem_destroy(dsc);
 	}
-	destroy_dev_sched_cb(cdev, vmmdev_destroy, sc);
+	destroy_dev(cdev);
+	vmmdev_destroy(sc);
 	error = 0;
 
 out: