From 8c22654d7e84fa0883058d9cb89b2b9c76556747 Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Fri, 17 Dec 2010 22:41:22 +0000
Subject: [PATCH] Implement and use a single optimized function for unholding a
 set of pages.

Reviewed by:	kib@
---
 sys/dev/cxgb/ulp/tom/cxgb_cpl_socket.c |  4 ++--
 sys/dev/cxgb/ulp/tom/cxgb_ddp.c        |  4 ++--
 sys/dev/cxgb/ulp/tom/cxgb_vm.c         | 13 ------------
 sys/dev/cxgb/ulp/tom/cxgb_vm.h         |  1 -
 sys/kern/sys_pipe.c                    | 15 +++----------
 sys/kern/vfs_bio.c                     |  7 +------
 sys/vm/vm_page.c                       | 29 ++++++++++++++++++++++++++
 sys/vm/vm_page.h                       |  1 +
 8 files changed, 38 insertions(+), 36 deletions(-)

diff --git a/sys/dev/cxgb/ulp/tom/cxgb_cpl_socket.c b/sys/dev/cxgb/ulp/tom/cxgb_cpl_socket.c
index bbb594ac2b2c..33f1dd15fb7e 100644
--- a/sys/dev/cxgb/ulp/tom/cxgb_cpl_socket.c
+++ b/sys/dev/cxgb/ulp/tom/cxgb_cpl_socket.c
@@ -454,7 +454,7 @@ sendmore:
 	while (uiotmp.uio_resid > 0) {
 		rv = cxgb_vm_page_to_miov(toep, &uiotmp, &m);
 		if (rv) {
-			vm_fault_unhold_pages(toep->tp_pages, count);
+			vm_page_unhold_pages(toep->tp_pages, count);
 			return (rv);
 		}
 		uio->uio_resid -= m->m_pkthdr.len;
@@ -469,7 +469,7 @@ sendmore:
 	 * 
 	 */
 	cxgb_wait_dma_completion(toep);
-	vm_fault_unhold_pages(toep->tp_pages, count);
+	vm_page_unhold_pages(toep->tp_pages, count);
 	/*
 	 * If there is more data to send adjust local copy of iov
 	 * to point to teh start
diff --git a/sys/dev/cxgb/ulp/tom/cxgb_ddp.c b/sys/dev/cxgb/ulp/tom/cxgb_ddp.c
index a54598c60672..a188f620afba 100644
--- a/sys/dev/cxgb/ulp/tom/cxgb_ddp.c
+++ b/sys/dev/cxgb/ulp/tom/cxgb_ddp.c
@@ -175,7 +175,7 @@ different_gl:
 	*newgl = p;
 	return (0);
 unpin:
-	vm_fault_unhold_pages(p->dgl_pages, npages);
+	vm_page_unhold_pages(p->dgl_pages, npages);
 
 free_gl:
 	
@@ -208,7 +208,7 @@ ddp_gl_free_pages(struct ddp_gather_list *gl, int dirty)
 	/*
 	 * XXX mark pages as dirty before unholding 
 	 */
-	vm_fault_unhold_pages(gl->dgl_pages, gl->dgl_nelem);
+	vm_page_unhold_pages(gl->dgl_pages, gl->dgl_nelem);
 }
 
 void
diff --git a/sys/dev/cxgb/ulp/tom/cxgb_vm.c b/sys/dev/cxgb/ulp/tom/cxgb_vm.c
index 4659788f0bb5..d7328b6a8eae 100644
--- a/sys/dev/cxgb/ulp/tom/cxgb_vm.c
+++ b/sys/dev/cxgb/ulp/tom/cxgb_vm.c
@@ -150,16 +150,3 @@ error:
 		}
 	return (EFAULT);
 }
-
-void
-vm_fault_unhold_pages(vm_page_t *mp, int count)
-{
-
-	KASSERT(count >= 0, ("negative count %d", count));
-	while (count--) {
-		vm_page_lock(*mp);
-		vm_page_unhold(*mp);
-		vm_page_unlock(*mp);
-		mp++;
-	}
-}
diff --git a/sys/dev/cxgb/ulp/tom/cxgb_vm.h b/sys/dev/cxgb/ulp/tom/cxgb_vm.h
index 7532e20ef78f..6647d553391c 100644
--- a/sys/dev/cxgb/ulp/tom/cxgb_vm.h
+++ b/sys/dev/cxgb/ulp/tom/cxgb_vm.h
@@ -34,6 +34,5 @@ $FreeBSD$
 
 int vm_fault_hold_user_pages(vm_map_t map, vm_offset_t addr,
     vm_page_t *mp, int count, vm_prot_t prot);
-void vm_fault_unhold_pages(vm_page_t *mp, int count);
 
 #endif
diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
index 22401a7a8a60..444b4240ba79 100644
--- a/sys/kern/sys_pipe.c
+++ b/sys/kern/sys_pipe.c
@@ -749,7 +749,7 @@ pipe_build_write_buffer(wpipe, uio)
 {
 	pmap_t pmap;
 	u_int size;
-	int i, j;
+	int i;
 	vm_offset_t addr, endaddr;
 
 	PIPE_LOCK_ASSERT(wpipe, MA_NOTOWNED);
@@ -771,11 +771,7 @@ pipe_build_write_buffer(wpipe, uio)
 		 */
 	race:
 		if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0) {
-			for (j = 0; j < i; j++) {
-				vm_page_lock(wpipe->pipe_map.ms[j]);
-				vm_page_unhold(wpipe->pipe_map.ms[j]);
-				vm_page_unlock(wpipe->pipe_map.ms[j]);
-			}
+			vm_page_unhold_pages(wpipe->pipe_map.ms, i);
 			return (EFAULT);
 		}
 		wpipe->pipe_map.ms[i] = pmap_extract_and_hold(pmap, addr,
@@ -812,14 +808,9 @@ static void
 pipe_destroy_write_buffer(wpipe)
 	struct pipe *wpipe;
 {
-	int i;
 
 	PIPE_LOCK_ASSERT(wpipe, MA_OWNED);
-	for (i = 0; i < wpipe->pipe_map.npages; i++) {
-		vm_page_lock(wpipe->pipe_map.ms[i]);
-		vm_page_unhold(wpipe->pipe_map.ms[i]);
-		vm_page_unlock(wpipe->pipe_map.ms[i]);
-	}
+	vm_page_unhold_pages(wpipe->pipe_map.ms, wpipe->pipe_map.npages);
 	wpipe->pipe_map.npages = 0;
 }
 
diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index ccde4b4ab4bc..7d04e3344ef6 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -3911,16 +3911,11 @@ retry:
 void
 vunmapbuf(struct buf *bp)
 {
-	int pidx;
 	int npages;
 
 	npages = bp->b_npages;
 	pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
-	for (pidx = 0; pidx < npages; pidx++) {
-		vm_page_lock(bp->b_pages[pidx]);
-		vm_page_unhold(bp->b_pages[pidx]);
-		vm_page_unlock(bp->b_pages[pidx]);
-	}
+	vm_page_unhold_pages(bp->b_pages, npages);
 	
 	bp->b_data = bp->b_saveaddr;
 }
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 1208ea07fb5c..e708a5706fcd 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -600,6 +600,35 @@ vm_page_unhold(vm_page_t mem)
 		vm_page_free_toq(mem);
 }
 
+/*
+ *	vm_page_unhold_pages:
+ *
+ *	Unhold each of the pages that is referenced by the given array.
+ */ 
+void
+vm_page_unhold_pages(vm_page_t *ma, int count)
+{
+	struct mtx *mtx, *new_mtx;
+
+	mtx = NULL;
+	for (; count != 0; count--) {
+		/*
+		 * Avoid releasing and reacquiring the same page lock.
+		 */
+		new_mtx = vm_page_lockptr(*ma);
+		if (mtx != new_mtx) {
+			if (mtx != NULL)
+				mtx_unlock(mtx);
+			mtx = new_mtx;
+			mtx_lock(mtx);
+		}
+		vm_page_unhold(*ma);
+		ma++;
+	}
+	if (mtx != NULL)
+		mtx_unlock(mtx);
+}
+
 /*
  *	vm_page_free:
  *
diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index e4183b38499e..54a15fb78c7a 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -364,6 +364,7 @@ void vm_page_set_valid(vm_page_t m, int base, int size);
 void vm_page_sleep(vm_page_t m, const char *msg);
 vm_page_t vm_page_splay(vm_pindex_t, vm_page_t);
 vm_offset_t vm_page_startup(vm_offset_t vaddr);
+void vm_page_unhold_pages(vm_page_t *ma, int count);
 void vm_page_unwire (vm_page_t, int);
 void vm_page_wire (vm_page_t);
 void vm_page_set_validclean (vm_page_t, int, int);