tree e72b55a4e0ba457776d70c3cad7b7d98ec4dcaf2
parent 89a31bf85c7b99e8f501f5b8559577983017e27e
author Chuck Lever <chuck.lever@oracle.com> 1618855361 -0400
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1621411984 +0200

xprtrdma: Fix cwnd update ordering

[ Upstream commit 35d8b10a25884050bb3b0149b62c3818ec59f77c ]

After a reconnect, the reply handler is opening the cwnd (and thus
enabling more RPC Calls to be sent) /before/ rpcrdma_post_recvs()
can post enough Receive WRs to receive their replies. This causes an
RNR and the new connection is lost immediately.

The race is most clearly exposed when KASAN and disconnect injection
are enabled. This slows down rpcrdma_rep_create() enough to allow
the send side to post a bunch of RPC Calls before the Receive
completion handler can invoke ib_post_recv().

Fixes: 2ae50ad68cd7 ("xprtrdma: Close window between waking RPC senders and posting Receives")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>