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authorGuoqing Jiang <gqjiang@suse.com>2015-07-10 12:01:15 +0300
committerNeilBrown <neilb@suse.com>2015-08-31 20:41:41 +0300
commit66099bb0ee6c20f91ace3fa5f82202fbceb67d8e (patch)
tree9b5be424509589322b12a9a6d1571e0b32111731 /Documentation/md-cluster.txt
parentdc737d7c3d62d2cd2b62c7739aaa7604330c3dd8 (diff)
downloadlinux-66099bb0ee6c20f91ace3fa5f82202fbceb67d8e.tar.xz
md-cluster: fix deadlock issue on message lock
There is problem with previous communication mechanism, and we got below deadlock scenario with cluster which has 3 nodes. Sender Receiver Receiver token(EX) message(EX) writes message downconverts message(CR) requests ack(EX) get message(CR) gets message(CR) reads message reads message requests EX on message requests EX on message To fix this problem, we do the following changes: 1. the sender downconverts MESSAGE to CW rather than CR. 2. and the receiver request PR lock not EX lock on message. And in case we failed to down-convert EX to CW on message, it is better to unlock message otherthan still hold the lock. Reviewed-by: Goldwyn Rodrigues <rgoldwyn@suse.com> Signed-off-by: Lidong Zhong <ldzhong@suse.com> Signed-off-by: Guoqing Jiang <gqjiang@suse.com> Signed-off-by: NeilBrown <neilb@suse.com>
Diffstat (limited to 'Documentation/md-cluster.txt')
-rw-r--r--Documentation/md-cluster.txt4
1 files changed, 2 insertions, 2 deletions
diff --git a/Documentation/md-cluster.txt b/Documentation/md-cluster.txt
index de1af7db3355..1b794369e03a 100644
--- a/Documentation/md-cluster.txt
+++ b/Documentation/md-cluster.txt
@@ -91,7 +91,7 @@ The algorithm is:
this message inappropriate or redundant.
3. sender write LVB.
- sender down-convert MESSAGE from EX to CR
+ sender down-convert MESSAGE from EX to CW
sender try to get EX of ACK
[ wait until all receiver has *processed* the MESSAGE ]
@@ -112,7 +112,7 @@ The algorithm is:
sender down-convert ACK from EX to CR
sender release MESSAGE
sender release TOKEN
- receiver upconvert to EX of MESSAGE
+ receiver upconvert to PR of MESSAGE
receiver get CR of ACK
receiver release MESSAGE