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e144c58cad
While closing, new rx data may be received after the input buffers
have been flushed but before stop_rx() halts receiving [1]. The
new data might not be processed by flush_to_ldisc() until after
uart_shutdown() and normal input processing is re-enabled (ie.,
tty->closing = 0). The race is outlined below:
CPU 0 | CPU 1
|
uart_close() |
tty_port_close_start() |
tty->closing = 1 |
tty_ldisc_flush() |
| => IRQ
| while (LSR & data ready)
| uart_insert_char()
| tty_flip_buffer_push()
| <= EOI
stop_rx() | .
uart_shutdown() | .
free xmit.buf | .
tty_port_tty_set(NULL) | .
tty->closing = 0 | .
| flush_to_ldisc()
| n_tty_receive_buf_common()
| __receive_buf()
| ...
| commit_echoes()
| uart_flush_chars()
| __uart_start()
| ** OOPS on port.tty deref **
tty_ldisc_flush() |
Input processing must be prevented from echoing (tty->closing = 1)
until _after_ the input buffers have been flushed again at the end
of uart_close().
[1] In fact, some input may actually be buffered _after_ stop_rx()
since the rx interrupt may have already triggered but not yet been
handled when stop_rx() disables rx interrupts.
Fixes:
|
||
---|---|---|
.. | ||
hvc | ||
ipwireless | ||
serial | ||
vt | ||
amiserial.c | ||
bfin_jtag_comm.c | ||
cyclades.c | ||
ehv_bytechan.c | ||
goldfish.c | ||
isicom.c | ||
Kconfig | ||
Makefile | ||
metag_da.c | ||
mips_ejtag_fdc.c | ||
moxa.c | ||
moxa.h | ||
mxser.c | ||
mxser.h | ||
n_gsm.c | ||
n_hdlc.c | ||
n_r3964.c | ||
n_tracerouter.c | ||
n_tracesink.c | ||
n_tracesink.h | ||
n_tty.c | ||
nozomi.c | ||
pty.c | ||
rocket.c | ||
rocket.h | ||
rocket_int.h | ||
synclink.c | ||
synclink_gt.c | ||
synclinkmp.c | ||
sysrq.c | ||
tty_audit.c | ||
tty_buffer.c | ||
tty_io.c | ||
tty_ioctl.c | ||
tty_ldisc.c | ||
tty_ldsem.c | ||
tty_mutex.c | ||
tty_port.c |