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authorClaire Chang <tientzu@chromium.org>2020-12-14 15:29:21 +0800
committerMarcel Holtmann <marcel@holtmann.org>2020-12-18 22:25:30 +0100
commitafe0b1c86458f121b085271e4f3034017a90d4a3 (patch)
treebae859cd58fa412d934a0d5b8571984ec25e65f4
parentc0187b0bd3e94c48050687d87b2c3c9fbae98ae9 (diff)
Bluetooth: hci_uart: Fix a race for write_work scheduling
In hci_uart_write_work, there is a loop/goto checking the value of HCI_UART_TX_WAKEUP. If HCI_UART_TX_WAKEUP is set again, it keeps trying hci_uart_dequeue; otherwise, it clears HCI_UART_SENDING and returns. In hci_uart_tx_wakeup, if HCI_UART_SENDING is already set, it sets HCI_UART_TX_WAKEUP, skips schedule_work and assumes the running/pending hci_uart_write_work worker will do hci_uart_dequeue properly. However, if the HCI_UART_SENDING check in hci_uart_tx_wakeup is done after the loop breaks, but before HCI_UART_SENDING is cleared in hci_uart_write_work, the schedule_work is skipped incorrectly. Fix this race by changing the order of HCI_UART_SENDING and HCI_UART_TX_WAKEUP modification. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 82f5169bf3d3 ("Bluetooth: hci_uart: add serdev driver support library") Signed-off-by: Claire Chang <tientzu@chromium.org> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
-rw-r--r--drivers/bluetooth/hci_ldisc.c7
-rw-r--r--drivers/bluetooth/hci_serdev.c4
2 files changed, 5 insertions, 6 deletions
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index f83d67eafc9f..8be4d807d137 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -127,10 +127,9 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
goto no_schedule;
- if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) {
- set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+ set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
+ if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state))
goto no_schedule;
- }
BT_DBG("");
@@ -174,10 +173,10 @@ restart:
kfree_skb(skb);
}
+ clear_bit(HCI_UART_SENDING, &hu->tx_state);
if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
goto restart;
- clear_bit(HCI_UART_SENDING, &hu->tx_state);
wake_up_bit(&hu->tx_state, HCI_UART_SENDING);
}
diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c
index ef96ad06fa54..9e03402ef1b3 100644
--- a/drivers/bluetooth/hci_serdev.c
+++ b/drivers/bluetooth/hci_serdev.c
@@ -83,9 +83,9 @@ static void hci_uart_write_work(struct work_struct *work)
hci_uart_tx_complete(hu, hci_skb_pkt_type(skb));
kfree_skb(skb);
}
- } while (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state));
- clear_bit(HCI_UART_SENDING, &hu->tx_state);
+ clear_bit(HCI_UART_SENDING, &hu->tx_state);
+ } while (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state));
}
/* ------- Interface to HCI layer ------ */