linux-kernel - [PATCH v2] cifs: Do not modify mid entry after submitting I/O in cifs_call

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Message-Id: <1498676163-31746-1-git-send-email-longli@exchange.microsoft.com>
Date:   Wed, 28 Jun 2017 11:56:03 -0700
From:   Long Li <longli@...hange.microsoft.com>
To:     Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org, linux-kernel@...r.kernel.org
Cc:     Long Li <longli@...rosoft.com>
Subject: [PATCH v2] cifs: Do not modify mid entry after submitting I/O in cifs_call_async

From: Long Li <longli@...rosoft.com>

In cifs_call_async, server may respond as soon as I/O is submitted. Because 
mid entry is freed on the return path, it should not be modified after I/O 
is submitted.

cifs_save_when_sent modifies the sent timestamp in mid entry, and should not
be called after I/O. Call it before I/O.

Signed-off-by: Long Li <longli@...rosoft.com>
---
 fs/cifs/transport.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 47a125e..ba62aaf 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -537,10 +537,10 @@ cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
 	spin_unlock(&GlobalMid_Lock);
 
 
+	cifs_save_when_sent(mid);
 	cifs_in_send_inc(server);
 	rc = smb_send_rqst(server, rqst, flags);
 	cifs_in_send_dec(server);
-	cifs_save_when_sent(mid);
 
 	if (rc < 0) {
 		server->sequence_number -= 2;
-- 
2.7.4