Date: Fri, 1 Feb 2002 04:43:39 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: <alfred@freebsd.org> Cc: <current@freebsd.org> Subject: lock reversal in fdalloc() Message-ID: <20020201043751.O5590-100000@gamplex.bde.org>
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Jan 31 18:27:29 gamplex kernel: lock order reversal
Jan 31 18:27:29 gamplex kernel: 1st 0xc26ea034 filedesc structure @ ./@/kern/kern_descrip.c:925
Jan 31 18:27:29 gamplex kernel: 2nd 0xc031eca0 Giant @ ./@/kern/kern_descrip.c:959
%%%
Index: kern_descrip.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_descrip.c,v
retrieving revision 1.122
diff -u -2 -r1.122 kern_descrip.c
--- kern_descrip.c 29 Jan 2002 22:54:19 -0000 1.122
+++ kern_descrip.c 31 Jan 2002 07:32:43 -0000
@@ -957,7 +967,9 @@
fdexpand++;
if (oldofile != NULL) {
+ FILEDESC_UNLOCK(fdp);
mtx_lock(&Giant);
FREE(oldofile, M_FILEDESC);
mtx_unlock(&Giant);
+ FILEDESC_LOCK(fdp);
}
}
%%%
I'm not sure that releasing the lock here is safe, but other parts of
fdalloc() do this.
Bruce
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