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Jia-Ju Bai fe8e7acea2 tty/isicom: Fix a possible sleep-in-atomic bug in WaitTillCardIsFree ...

The driver may sleep under a spinlock.
The function call paths are:
isicom_activate (acquire the spinlock)
  isicom_setup_board
    drop_dtr_rts
      WaitTillCardIsFree
        msleep --> may sleep

isicom_set_termios
  isicom_config_port
    drop_dtr
      WaitTillCardIsFree
        msleep --> may sleep

isicom_tiocmset
  drop_dtr
    WaitTillCardIsFree
      msleep --> may sleep

Though "in_atomic" is used to check atomic context,
but it is not recommended to use in driver code (see include/linux/preempt.h).

To fix it, only using mdelay instead.

This bug is found by my static analysis tool(DSAC) and checked by my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2017-12-15 20:24:14 +01:00

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