ALSA: seq: Remove arbitrary prioq insertion limit

The sequencer priority queue insertion path uses a hardcoded traversal
limit of 10000 entries.  The value is intended to catch a corrupted list,
but it also becomes a real limit for valid queues.

The event pool limit is per client, while a sequencer queue can be shared
by multiple clients.  A queue can therefore legitimately contain more than
10000 events.  In that case, inserting an event that has to be placed past
the arbitrary limit fails with -EINVAL.

Use the queue's own cell count as the traversal bound instead.  This keeps
the protection against inconsistent list accounting or cyclic lists without
rejecting valid large queues.

Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260525-alsa-seq-prioq-limit-v1-1-16c348df5ff7@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/seq/seq_prioq.c b/sound/core/seq/seq_prioq.c
index 25c0ed8f9f0f81865e607b2850cc2aae85cfbda9..d5bad1c585f64d9b0f92a1a0010684c1e6774ba3 100644 (file)
--- a/sound/core/seq/seq_prioq.c
+++ b/sound/core/seq/seq_prioq.c
@@ -132,7 +132,7 @@ int snd_seq_prioq_cell_in(struct snd_seq_prioq * f,
                          struct snd_seq_event_cell * cell)
 {
        struct snd_seq_event_cell *cur, *prev;
-       int count;
+       int remaining;
        int prior;
 
        if (snd_BUG_ON(!f || !cell))
@@ -162,10 +162,16 @@ int snd_seq_prioq_cell_in(struct snd_seq_prioq * f,
        prev = NULL;            /* previous cell */
        cur = f->head;          /* cursor */
 
-       count = 10000; /* FIXME: enough big, isn't it? */
+       remaining = f->cells;
        while (cur != NULL) {
                /* compare timestamps */
                int rel = compare_timestamp_rel(&cell->event, &cur->event);
+
+               if (remaining-- <= 0) {
+                       pr_err("ALSA: seq: inconsistent prioq cell count\n");
+                       return -EINVAL;
+               }
+
                if (rel < 0)
                        /* new cell has earlier schedule time, */
                        break;
@@ -176,10 +182,6 @@ int snd_seq_prioq_cell_in(struct snd_seq_prioq * f,
                /* move cursor to next cell */
                prev = cur;
                cur = cur->next;
-               if (! --count) {
-                       pr_err("ALSA: seq: cannot find a pointer.. infinite loop?\n");
-                       return -EINVAL;
-               }
        }
 
        /* insert it before cursor */