[DLM] fix requestqueue race
Red Hat BZ 211914 There's a race between dlm_recoverd (1) enabling locking and (2) clearing out the requestqueue, and dlm_recvd (1) checking if locking is enabled and (2) adding a message to the requestqueue. An order of recoverd(1), recvd(1), recvd(2), recoverd(2) will result in a message being left on the requestqueue. The fix is to have dlm_recvd check if dlm_recoverd has enabled locking after taking the mutex for the requestqueue and if it has processing the message instead of queueing it. Signed-off-by: David Teigland <teigland@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
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@ -3028,10 +3028,17 @@ int dlm_receive_message(struct dlm_header *hd, int nodeid, int recovery)
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while (1) {
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if (dlm_locking_stopped(ls)) {
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if (!recovery)
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dlm_add_requestqueue(ls, nodeid, hd);
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error = -EINTR;
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goto out;
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if (recovery) {
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error = -EINTR;
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goto out;
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}
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error = dlm_add_requestqueue(ls, nodeid, hd);
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if (error == -EAGAIN)
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continue;
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else {
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error = -EINTR;
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goto out;
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}
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}
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if (lock_recovery_try(ls))
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@ -30,26 +30,39 @@ struct rq_entry {
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* lockspace is enabled on some while still suspended on others.
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*/
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void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd)
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int dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd)
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{
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struct rq_entry *e;
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int length = hd->h_length;
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int rv = 0;
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if (dlm_is_removed(ls, nodeid))
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return;
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return 0;
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e = kmalloc(sizeof(struct rq_entry) + length, GFP_KERNEL);
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if (!e) {
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log_print("dlm_add_requestqueue: out of memory\n");
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return;
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return 0;
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}
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e->nodeid = nodeid;
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memcpy(e->request, hd, length);
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/* We need to check dlm_locking_stopped() after taking the mutex to
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avoid a race where dlm_recoverd enables locking and runs
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process_requestqueue between our earlier dlm_locking_stopped check
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and this addition to the requestqueue. */
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mutex_lock(&ls->ls_requestqueue_mutex);
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list_add_tail(&e->list, &ls->ls_requestqueue);
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if (dlm_locking_stopped(ls))
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list_add_tail(&e->list, &ls->ls_requestqueue);
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else {
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log_debug(ls, "dlm_add_requestqueue skip from %d", nodeid);
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kfree(e);
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rv = -EAGAIN;
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}
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mutex_unlock(&ls->ls_requestqueue_mutex);
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return rv;
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}
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int dlm_process_requestqueue(struct dlm_ls *ls)
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@ -13,7 +13,7 @@
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#ifndef __REQUESTQUEUE_DOT_H__
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#define __REQUESTQUEUE_DOT_H__
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void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd);
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int dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_header *hd);
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int dlm_process_requestqueue(struct dlm_ls *ls);
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void dlm_wait_requestqueue(struct dlm_ls *ls);
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void dlm_purge_requestqueue(struct dlm_ls *ls);
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