From owner-freebsd-current  Thu Jan 31  9:42:17 2002
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Date: Fri, 1 Feb 2002 04:43:39 +1100 (EST)
From: Bruce Evans <bde@zeta.org.au>
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To: <alfred@freebsd.org>
Cc: <current@freebsd.org>
Subject: lock reversal in fdalloc()
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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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