A user reported a crash in cifs_demultiplex_thread() caused by an
incorrectly set mid_q_entry->callback() function. It appears that the
callback assignment made in cifs_call_async() was not flushed back to
memory suggesting that a memory barrier was required here. Changing the
code to make sure that the mid_q_entry structure was completely
initialised before it was added to the pending queue fixes the problem.
Signed-off-by: Sachin Prabhu <sprabhu@xxxxxxxxxx>
---
fs/cifs/transport.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 3097ee5..f25d4ea 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -365,16 +365,14 @@ cifs_setup_async_request(struct TCP_Server_Info *server, struct kvec *iov,
if (mid == NULL)
return -ENOMEM;
- /* put it on the pending_mid_q */
- spin_lock(&GlobalMid_Lock);
- list_add_tail(&mid->qhead, &server->pending_mid_q);
- spin_unlock(&GlobalMid_Lock);
-
rc = cifs_sign_smb2(iov, nvec, server, &mid->sequence_number);
- if (rc)
- delete_mid(mid);
+ if (rc) {
+ DeleteMidQEntry(mid);
+ return rc;
+ }
+
*ret_mid = mid;
- return rc;
+ return 0;
}
/*
@@ -407,17 +405,21 @@ cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
mid->callback_data = cbdata;
mid->mid_state = MID_REQUEST_SUBMITTED;
+ /* put it on the pending_mid_q */
+ spin_lock(&GlobalMid_Lock);
+ list_add_tail(&mid->qhead, &server->pending_mid_q);
+ spin_unlock(&GlobalMid_Lock);
+
+
cifs_in_send_inc(server);
rc = smb_sendv(server, iov, nvec);
cifs_in_send_dec(server);
cifs_save_when_sent(mid);
mutex_unlock(&server->srv_mutex);
- if (rc)
- goto out_err;
+ if (rc == 0)
+ return 0;
- return rc;
-out_err:
delete_mid(mid);
add_credits(server, 1);
wake_up(&server->request_q);
--
1.7.10.4
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