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authorPeter Hurley <peter@hurleysoftware.com>2014-09-02 23:39:13 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-09-09 01:22:42 +0200
commitc235ccc1c4d6fd8b7d48b976b87416230ffd5149 (patch)
tree57121108b002bd0f74c4f8efce18dbf823564d2a /Documentation/serial
parentserial: imx: Fix x_char handling and tx flow control (diff)
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serial: core: Fix x_char race
The UART driver is expected to clear port->x_char after transmission while holding the port->lock. However, the serial core fails to take the port->lock before assigning port->xchar. This allows for the following race CPU 0 | CPU 1 | | serial8250_handle_irq | ... | serial8250_tx_chars | if (port->x_char) | serial_out(up, UART_TX, port->x_char) uart_send_xchar | port->x_char = ch | | port->x_char = 0 port->ops->start_tx() | | The x_char on CPU 0 will never be sent. Take the port->lock in uart_send_xchar() before assigning port->x_char. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/serial')
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