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Bluetooth: drivers/h4: Add support for discarding certain events

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If we are low on RX buffers and receive an LE Advertising Report or a
BR/EDR Inquiry response we should just discard this. If we don't
discard the event we increase the risk of deadlock where the RX
interrupt is enabled but bt_recv() is doing a synchronous HCI command
sending, i.e. waiting for a cmd_status/cmd_complete (which will never
come since the RX interrupt is disabled).

Change-Id: I6266625c9790d68bcf8e8718c8c36f127946c4c6
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
This commit is contained in:
Johan Hedberg 2017-01-31 11:24:37 +02:00
commit bbf389aae6
1 changed files with 50 additions and 15 deletions
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65
drivers/bluetooth/hci/h4.c
View file

@ -46,11 +46,15 @@ static struct {
uint16_t discard;
bool have_hdr;
bool discardable;
uint8_t hdr_len;
uint8_t type;
union {
struct bt_hci_evt_hdr evt;
struct bt_hci_acl_hdr acl;
uint8_t hdr[4];
};
} rx = {
.fifo = K_FIFO_INITIALIZER(rx.fifo),
@ -78,9 +82,11 @@ static inline void h4_get_type(void)
switch (rx.type) {
case H4_EVT:
rx.remaining = sizeof(rx.evt);
rx.hdr_len = rx.remaining;
break;
case H4_ACL:
rx.remaining = sizeof(rx.acl);
rx.hdr_len = rx.remaining;
break;
default:
BT_ERR("Unknown H:4 type 0x%02x", rx.type);
@ -105,13 +111,34 @@ static inline void get_acl_hdr(void)
static inline void get_evt_hdr(void)
{
struct bt_hci_evt_hdr *hdr = &rx.evt;
int to_read = sizeof(*hdr) - rx.remaining;
int to_read = rx.hdr_len - rx.remaining;
rx.remaining -= uart_fifo_read(h4_dev, (uint8_t *)hdr + to_read,
rx.remaining);
if (rx.hdr_len == sizeof(*hdr) && rx.remaining < sizeof(*hdr)) {
switch (rx.evt.evt) {
case BT_HCI_EVT_LE_META_EVENT:
rx.remaining++;
rx.hdr_len++;
break;
#if defined(CONFIG_BLUETOOTH_BREDR)
case BT_HCI_EVT_INQUIRY_RESULT_WITH_RSSI:
case BT_HCI_EVT_EXTENDED_INQUIRY_RESULT:
rx.discardable = true;
break;
#endif
}
}
if (!rx.remaining) {
rx.remaining = hdr->len;
BT_DBG("Got event header. Payload %u bytes", rx.remaining);
if (rx.evt.evt == BT_HCI_EVT_LE_META_EVENT &&
rx.hdr[sizeof(*hdr)] == BT_HCI_EVT_LE_ADVERTISING_REPORT) {
BT_DBG("Marking adv report as discardable");
rx.discardable = true;
}
rx.remaining = hdr->len - (rx.hdr_len - sizeof(*hdr));
BT_DBG("Got event header. Payload %u bytes", hdr->len);
rx.have_hdr = true;
}
}
@ -119,13 +146,7 @@ static inline void get_evt_hdr(void)
static inline void copy_hdr(struct net_buf *buf)
{
if (rx.type == H4_EVT) {
net_buf_add_mem(buf, &rx.evt, sizeof(rx.evt));
BT_DBG("buf %p EVT len %u", buf, sys_le16_to_cpu(rx.evt.len));
} else {
net_buf_add_mem(buf, &rx.acl, sizeof(rx.acl));
BT_DBG("buf %p ACL len %u", buf, sys_le16_to_cpu(rx.acl.len));
}
net_buf_add_mem(buf, rx.hdr, rx.hdr_len);
}
static void rx_thread(void *p1, void *p2, void *p3)
@ -183,6 +204,15 @@ static size_t h4_discard(struct device *uart, size_t len)
return uart_fifo_read(uart, buf, min(len, sizeof(buf)));
}
static void reset_rx(void)
{
rx.type = H4_NONE;
rx.remaining = 0;
rx.have_hdr = false;
rx.hdr_len = 0;
rx.discardable = false;
}
static inline void read_payload(void)
{
struct net_buf *buf;
@ -192,7 +222,14 @@ static inline void read_payload(void)
if (!rx.buf) {
rx.buf = bt_buf_get_rx(K_NO_WAIT);
if (!rx.buf) {
BT_DBG("Failed to allocate, deferring to rx_thread");
if (rx.discardable) {
BT_WARN("Discarding event 0x%02x", rx.evt.evt);
rx.discard = rx.remaining;
reset_rx();
return;
}
BT_WARN("Failed to allocate, deferring to rx_thread");
uart_irq_rx_disable(h4_dev);
return;
}
@ -202,8 +239,7 @@ static inline void read_payload(void)
if (rx.remaining > net_buf_tailroom(rx.buf)) {
BT_ERR("Not enough space in buffer");
rx.discard = rx.remaining;
rx.remaining = 0;
rx.have_hdr = false;
reset_rx();
return;
}
@ -233,8 +269,7 @@ static inline void read_payload(void)
bt_buf_set_type(buf, BT_BUF_ACL_IN);
}
rx.type = H4_NONE;
rx.have_hdr = false;
reset_rx();
if (prio) {
BT_DBG("Calling bt_recv_prio(%p)", buf);