From 2a016de1a5abdf87ae6e00f879a3600d157a8ca2 Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Mon, 20 Mar 2017 05:15:55 +0000
Subject: [PATCH] Use IDX_TO_OFF(), not ptoa(), when converting the difference
between two vm_pindex_t's into a vm_ooffset_t.
The length given to shm_dotruncate() must never be negative. Assert this.
Tidy up a comment.
Reviewed by: kib
MFC after: 1 week
---
sys/kern/uipc_shm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c
index cd1bf0b7142c..55362c5ad704 100644
--- a/sys/kern/uipc_shm.c
+++ b/sys/kern/uipc_shm.c
@@ -418,6 +418,7 @@ shm_dotruncate(struct shmfd *shmfd, off_t length)
vm_ooffset_t delta;
int base, rv;
+ KASSERT(length >= 0, ("shm_dotruncate: length < 0"));
object = shmfd->shm_object;
VM_OBJECT_WLOCK(object);
if (length == shmfd->shm_size) {
@@ -486,7 +487,7 @@ retry:
vm_pager_page_unswapped(m);
}
}
- delta = ptoa(object->size - nobjsize);
+ delta = IDX_TO_OFF(object->size - nobjsize);
/* Toss in memory pages. */
if (nobjsize < object->size)
@@ -501,8 +502,8 @@ retry:
swap_release_by_cred(delta, object->cred);
object->charge -= delta;
} else {
- /* Attempt to reserve the swap */
- delta = ptoa(nobjsize - object->size);
+ /* Try to reserve additional swap space. */
+ delta = IDX_TO_OFF(nobjsize - object->size);
if (!swap_reserve_by_cred(delta, object->cred)) {
VM_OBJECT_WUNLOCK(object);
return (ENOMEM);