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Avoid race with "dev_rel()" when using the recently added

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"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@
This commit is contained in:
Hans Petter Selasky 2015-01-14 22:07:13 +00:00
parent 38feff972b
commit d2955419cd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=277199
2 changed files with 6 additions and 2 deletions
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6
sys/fs/devfs/devfs_devs.c
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@ -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);
}

2
sys/kern/kern_conf.c
View File

@ -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);