With Alfred's permission, remove vm_mtx in favor of a fine-grained approach

(this commit is just the first stage).  Also add various GIANT_ macros to
formalize the removal of Giant, making it easy to test in a more piecemeal
fashion. These macros will allow us to test fine-grained locks to a degree
before removing Giant, and also after, and to remove Giant in a piecemeal
fashion via sysctl's on those subsystems which the authors believe can
operate without Giant.

1 files changed, 3 insertions, 8 deletions

diff --git a/sys/fs/procfs/procfs_mem.c b/sys/fs/procfs/procfs_mem.c
index b8c60d6..e109146 100644
--- a/sys/fs/procfs/procfs_mem.c
+++ b/sys/fs/procfs/procfs_mem.c
@@ -83,6 +83,8 @@ procfs_rwmem(curp, p, uio)
 	vm_prot_t reqprot;
 	vm_offset_t kva;
 
+	GIANT_REQUIRED;
+
 	/*
 	 * if the vmspace is in the midst of being deallocated or the
 	 * process is exiting, don't try to grab anything.  The page table
@@ -91,12 +93,8 @@ procfs_rwmem(curp, p, uio)
 	vm = p->p_vmspace;
 	if ((p->p_flag & P_WEXIT))
 		return EFAULT;
-
-	mtx_lock(&vm_mtx);
-	if (vm->vm_refcnt < 1) {
-		mtx_unlock(&vm_mtx);
+	if (vm->vm_refcnt < 1)
 		return EFAULT;
-	}
 	++vm->vm_refcnt;
 	/*
 	 * The map we want...
@@ -214,9 +212,7 @@ procfs_rwmem(curp, p, uio)
 		/*
 		 * Now do the i/o move.
 		 */
-		mtx_unlock(&vm_mtx);
 		error = uiomove((caddr_t)(kva + page_offset), len, uio);
-		mtx_lock(&vm_mtx);
 
 		pmap_kremove(kva);
 
@@ -235,7 +231,6 @@ procfs_rwmem(curp, p, uio)
 
 	kmem_free(kernel_map, kva, PAGE_SIZE);
 	vmspace_free(vm);
-	mtx_unlock(&vm_mtx);
 	return (error);
 }