svn commit: r315442 - head/sys/compat/linuxkpi/common/include/linux
Hans Petter Selasky
hselasky at FreeBSD.org
Fri Mar 17 08:02:48 UTC 2017
Author: hselasky
Date: Fri Mar 17 08:02:46 2017
New Revision: 315442
URL: https://svnweb.freebsd.org/changeset/base/315442
Log:
Add comment describing the use of pagefault_disable() and
pagefault_enable() in the LinuxKPI.
Suggested by: rpokala@
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/sys/compat/linuxkpi/common/include/linux/uaccess.h
Modified: head/sys/compat/linuxkpi/common/include/linux/uaccess.h
==============================================================================
--- head/sys/compat/linuxkpi/common/include/linux/uaccess.h Fri Mar 17 07:56:20 2017 (r315441)
+++ head/sys/compat/linuxkpi/common/include/linux/uaccess.h Fri Mar 17 08:02:46 2017 (r315442)
@@ -67,6 +67,13 @@ extern int linux_copyout(const void *kad
extern size_t linux_clear_user(void *uaddr, size_t len);
extern int linux_access_ok(int rw, const void *uaddr, size_t len);
+/*
+ * NOTE: Each pagefault_disable() call must have a corresponding
+ * pagefault_enable() call in the same scope. The former creates a new
+ * block and defines a temporary variable, and the latter uses the
+ * temporary variable and closes the block. Failure to balance the
+ * calls will result in a compile-time error.
+ */
#define pagefault_disable(void) do { \
int __saved_pflags = \
vm_fault_disable_pagefaults()
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