diff options
| author | Mike Belopuhov <mikeb@cvs.openbsd.org> | 2017-01-05 11:47:03 +0000 |
|---|---|---|
| committer | Mike Belopuhov <mikeb@cvs.openbsd.org> | 2017-01-05 11:47:03 +0000 |
| commit | 004d74ddb0a738c454c384dbf32e51fa3fa4f386 (patch) | |
| tree | 1a069d4af8a11640de119f75ac1e65807aa8d9a3 /sys/dev | |
| parent | 1197886a3ec36e59181c881b0b35834155919d8f (diff) | |
Don't let producer index become equal with the consumer when writing
A nod to the re.c commit by dlg@, perhaps pure paranoia, but works
nevertheless. While here replace a more expensive modulo operation
with a subtraction.
Diffstat (limited to 'sys/dev')
| -rw-r--r-- | sys/dev/pv/hyperv.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/sys/dev/pv/hyperv.c b/sys/dev/pv/hyperv.c index 985b5949d14..d77fa7ecb6d 100644 --- a/sys/dev/pv/hyperv.c +++ b/sys/dev/pv/hyperv.c @@ -1242,7 +1242,8 @@ hv_ring_put(struct hv_ring_data *wrd, uint8_t *data, uint32_t datalen) memcpy(&wrd->rd_ring->br_data[wrd->rd_prod], data, left); memcpy(&wrd->rd_ring->br_data[0], data + left, datalen - left); wrd->rd_prod += datalen; - wrd->rd_prod %= wrd->rd_dsize; + if (wrd->rd_prod >= wrd->rd_dsize) + wrd->rd_prod -= wrd->rd_dsize; } static inline void @@ -1255,7 +1256,8 @@ hv_ring_get(struct hv_ring_data *rrd, uint8_t *data, uint32_t datalen, memcpy(data + left, &rrd->rd_ring->br_data[0], datalen - left); if (!peek) { rrd->rd_cons += datalen; - rrd->rd_cons %= rrd->rd_dsize; + if (rrd->rd_cons >= rrd->rd_dsize) + rrd->rd_cons -= rrd->rd_dsize; } } @@ -1291,7 +1293,7 @@ hv_ring_write(struct hv_ring_data *wrd, struct iovec *iov, int iov_cnt, KASSERT(datalen <= wrd->rd_dsize); hv_ring_avail(wrd, &avail, NULL); - if (avail < datalen) { + if (avail <= datalen) { DPRINTF("%s: avail %u datalen %u\n", __func__, avail, datalen); return (EAGAIN); } @@ -1432,7 +1434,8 @@ hv_ring_read(struct hv_ring_data *rrd, void *data, uint32_t datalen, if (offset) { rrd->rd_cons += offset; - rrd->rd_cons %= rrd->rd_dsize; + if (rrd->rd_cons >= rrd->rd_dsize) + rrd->rd_cons -= rrd->rd_dsize; } hv_ring_get(rrd, (uint8_t *)data, datalen, 0); |