Initialise mid_q_entry before putting it on the pending queue
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@redhat.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com> Signed-off-by: Steve French <smfrench@gmail.com>
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@ -365,16 +365,14 @@ cifs_setup_async_request(struct TCP_Server_Info *server, struct kvec *iov,
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if (mid == NULL)
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return -ENOMEM;
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/* put it on the pending_mid_q */
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spin_lock(&GlobalMid_Lock);
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list_add_tail(&mid->qhead, &server->pending_mid_q);
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spin_unlock(&GlobalMid_Lock);
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rc = cifs_sign_smb2(iov, nvec, server, &mid->sequence_number);
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if (rc)
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delete_mid(mid);
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if (rc) {
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DeleteMidQEntry(mid);
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return rc;
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}
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*ret_mid = mid;
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return rc;
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return 0;
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}
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/*
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@ -407,17 +405,21 @@ cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
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mid->callback_data = cbdata;
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mid->mid_state = MID_REQUEST_SUBMITTED;
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/* put it on the pending_mid_q */
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spin_lock(&GlobalMid_Lock);
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list_add_tail(&mid->qhead, &server->pending_mid_q);
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spin_unlock(&GlobalMid_Lock);
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cifs_in_send_inc(server);
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rc = smb_sendv(server, iov, nvec);
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cifs_in_send_dec(server);
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cifs_save_when_sent(mid);
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mutex_unlock(&server->srv_mutex);
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if (rc)
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goto out_err;
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if (rc == 0)
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return 0;
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return rc;
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out_err:
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delete_mid(mid);
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add_credits(server, 1);
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wake_up(&server->request_q);
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