From: Milan Broz <mbroz@redhat.com>
Date: Fri, 10 Oct 2008 12:37:07 +0000 (+0100)
Subject: dm crypt: fix async inc_pending
X-Git-Tag: v2.6.28-rc1~729^2~7
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=4e59409891c9cc30cb4d5d73250b0c968af8e39b;p=linux-2.6-omap-h63xx.git

dm crypt: fix async inc_pending

The pending reference count must be incremented *before* the async work is
queued to another thread, not after.  Otherwise there's a race if the
work completes and decrements the reference count before it gets incremented.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index d8126ac8296..262ed181669 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -719,16 +719,15 @@ static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
 
 		remaining -= clone->bi_size;
 
+		crypt_inc_pending(io);
 		r = crypt_convert(cc, &io->ctx);
 
 		if (atomic_dec_and_test(&io->ctx.pending)) {
 			/* processed, no running async crypto  */
-			crypt_inc_pending(io);
 			kcryptd_crypt_write_io_submit(io, r, 0);
 			if (unlikely(r < 0))
 				break;
-		} else
-			crypt_inc_pending(io);
+		}
 
 		/* out of memory -> run queues */
 		if (unlikely(remaining)) {