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Update userref handling after discussion with submitter of previous

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patch.  lf can't be dereferenced after the unload attempt, in case it
was freed.  Instead, decrement first and back it out if the unload failed.
This should be relatively immune to races caused by the user since the
userref count will be zero for the duration of the actual unloading and
will stop further kldunload attempts.

Submitted by:   Ustimenko Semen <semen@iclub.nsu.ru>
This commit is contained in:
Peter Wemm 1999-01-23 03:45:22 +00:00
parent 2c9b3ec2ff
commit 461b36ab54
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=43084
1 changed files with 4 additions and 4 deletions
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8
sys/kern/kern_linker.c
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@ -23,7 +23,7 @@
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: kern_linker.c,v 1.20 1999/01/19 16:26:32 peter Exp $
* $Id: kern_linker.c,v 1.21 1999/01/19 22:26:46 peter Exp $
*/
#include "opt_ddb.h"
@ -680,14 +680,14 @@ kldunload(struct proc* p, struct kldunload_args* uap)
if (lf) {
KLD_DPF(FILE, ("kldunload: lf->userrefs=%d\n", lf->userrefs));
if (lf->userrefs == 0) {
printf("linkerunload: attempt to unload file which was not loaded by user\n");
printf("linkerunload: attempt to unload file that was loaded by the kernel\n");
error = EBUSY;
goto out;
}
lf->userrefs--;
error = linker_file_unload(lf);
if (error)
goto out;
lf->userrefs--;
lf->userrefs++;
} else
error = ENOENT;