Author: hselasky
Date: Wed Jan 14 22:07:13 2015
New Revision: 277199
URL: https://svnweb.freebsd.org/changeset/base/277199
Log:
Avoid race with "dev_rel()" when using the recently added
"delist_dev()" function. Make sure the character device structure
doesn't go away until the end of the "destroy_dev()" function due to
concurrently running cleanup code inside "devfs_populate()".
MFC after: 1 week
Reported by: dchagin@
Modified:
head/sys/fs/devfs/devfs_devs.c
head/sys/kern/kern_conf.c
Modified: head/sys/fs/devfs/devfs_devs.c
==============================================================================
--- head/sys/fs/devfs/devfs_devs.c Wed Jan 14 22:05:57 2015
(r277198)
+++ head/sys/fs/devfs/devfs_devs.c Wed Jan 14 22:07:13 2015
(r277199)
@@ -137,6 +137,12 @@ devfs_alloc(int flags)
vfs_timestamp(&ts);
cdev->si_atime = cdev->si_mtime = cdev->si_ctime = ts;
cdev->si_cred = NULL;
+ /*
+ * Avoid race with dev_rel() by setting the initial
+ * reference count to 1. This last reference is taken
+ * by the destroy_dev() function.
+ */
+ cdev->si_refcount = 1;
return (cdev);
}
Modified: head/sys/kern/kern_conf.c
==============================================================================
--- head/sys/kern/kern_conf.c Wed Jan 14 22:05:57 2015 (r277198)
+++ head/sys/kern/kern_conf.c Wed Jan 14 22:07:13 2015 (r277199)
@@ -1048,8 +1048,6 @@ destroy_devl(struct cdev *dev)
/* Remove name marking */
dev->si_flags &= ~SI_NAMED;
- dev->si_refcount++; /* Avoid race with dev_rel() */
-
/* If we are a child, remove us from the parents list */
if (dev->si_flags & SI_CHILD) {
LIST_REMOVE(dev, si_siblings);
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
