diff options
Diffstat (limited to 'drivers/net/wireless')
| -rw-r--r-- | drivers/net/wireless/iwlwifi/pcie/rx.c | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/drivers/net/wireless/iwlwifi/pcie/rx.c b/drivers/net/wireless/iwlwifi/pcie/rx.c index 5fdb4eea146d..8c9641b863f7 100644 --- a/drivers/net/wireless/iwlwifi/pcie/rx.c +++ b/drivers/net/wireless/iwlwifi/pcie/rx.c @@ -112,15 +112,16 @@ */ static int iwl_rxq_space(const struct iwl_rxq *rxq) { - int s = rxq->read - rxq->write; - - if (s <= 0) - s += RX_QUEUE_SIZE; - /* keep some buffer to not confuse full and empty queue */ - s -= 2; - if (s < 0) - s = 0; - return s; + /* Make sure RX_QUEUE_SIZE is a power of 2 */ + BUILD_BUG_ON(RX_QUEUE_SIZE & (RX_QUEUE_SIZE - 1)); + + /* + * There can be up to (RX_QUEUE_SIZE - 1) free slots, to avoid ambiguity + * between empty and completely full queues. + * The following is equivalent to modulo by RX_QUEUE_SIZE and is well + * defined for negative dividends. + */ + return (rxq->read - rxq->write - 1) & (RX_QUEUE_SIZE - 1); } /* |