vm_map_lock_read() does not increment map->timestamp, so we should

compare map->timestamp with saved timestamp after map read lock is
reacquired, not with saved timestamp + 1. The only consequence of the +1
was unconditional lookup of the next map entry, though.

Tested by:	pho
Approved by:	des
MFC after:	2 weeks

3 files changed, 4 insertions, 4 deletions

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index 09c22e3..fc2eacb 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -980,7 +980,7 @@ linprocfs_doprocmaps(PFS_FILL_ARGS)
 			error = 0;
 			break;
 		}
-		if (last_timestamp + 1 != map->timestamp) {
+		if (last_timestamp != map->timestamp) {
 			/*
 			 * Look again for the entry because the map was
 			 * modified while it was unlocked.  Specifically,
diff --git a/sys/fs/procfs/procfs_map.c b/sys/fs/procfs/procfs_map.c
index 2d3c17e..ed04d38 100644
--- a/sys/fs/procfs/procfs_map.c
+++ b/sys/fs/procfs/procfs_map.c
@@ -224,7 +224,7 @@ procfs_doprocmap(PFS_FILL_ARGS)
 			error = 0;
 			break;
 		}
-		if (last_timestamp + 1 != map->timestamp) {
+		if (last_timestamp != map->timestamp) {
 			/*
 			 * Look again for the entry because the map was
 			 * modified while it was unlocked.  Specifically,
diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index 9c6225f..3d994ba 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -1500,7 +1500,7 @@ sysctl_kern_proc_ovmmap(SYSCTL_HANDLER_ARGS)
 		vm_map_lock_read(map);
 		if (error)
 			break;
-		if (last_timestamp + 1 != map->timestamp) {
+		if (last_timestamp != map->timestamp) {
 			vm_map_lookup_entry(map, addr - 1, &tmp_entry);
 			entry = tmp_entry;
 		}
@@ -1677,7 +1677,7 @@ sysctl_kern_proc_vmmap(SYSCTL_HANDLER_ARGS)
 		vm_map_lock_read(map);
 		if (error)
 			break;
-		if (last_timestamp + 1 != map->timestamp) {
+		if (last_timestamp != map->timestamp) {
 			vm_map_lookup_entry(map, addr - 1, &tmp_entry);
 			entry = tmp_entry;
 		}