ustd: use modulo value for first_subbuf

This prevented crash recovery when the buffer filled.

diff --git a/ustd/lowlevel.c b/ustd/lowlevel.c
index d8d4cfa32c80cc83c1f11d456d24016ac6365289..65657490d6044d13ce3aa31aa1797d7637aab3ef 100644 (file)
--- a/ustd/lowlevel.c
+++ b/ustd/lowlevel.c
@@ -91,7 +91,7 @@ void finish_consuming_dead_subbuffer(struct buffer_info *buf)
        }
 
        /* Iterate on subbuffers to recover. */
-       for(i_subbuf=first_subbuf; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
+       for(i_subbuf = first_subbuf % buf->n_subbufs; ; i_subbuf++, i_subbuf %= buf->n_subbufs) {
                void *tmp;
                /* commit_seq is the offset in the buffer of the end of the last sequential commit.
                 * Bytes beyond this limit cannot be recovered. This is a free-running counter. */