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staging: dgnc: Fix a sleep-in-atomic-context bug in cls_assert_modem_signals()

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The driver may sleep with holding a spinlock.
The function call path (from bottom to top) in Linux-4.17 is:

[FUNC] usleep_range
drivers/staging/dgnc/dgnc_cls.c, 391:
	usleep_range in cls_assert_modem_signals
drivers/staging/dgnc/dgnc_cls.c, 449:
	cls_assert_modem_signals in cls_copy_data_from_queue_to_uart
drivers/staging/dgnc/dgnc_cls.c, 406:
	_raw_spin_lock_irqsave in cls_copy_data_from_queue_to_uart

To fix this bug, usleep_range() is replaced with udelay().

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jia-Ju Bai 2018-09-15 11:13:03 +08:00 committed by Greg Kroah-Hartman
parent 2051c6ae92
commit bffa9b1cc6
1 changed files with 1 additions and 1 deletions
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2
drivers/staging/dgnc/dgnc_cls.c
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@ -388,7 +388,7 @@ static void cls_assert_modem_signals(struct channel_t *ch)
writeb(out, &ch->ch_cls_uart->mcr);
/* Give time for the UART to actually drop the signals */
usleep_range(10, 20);
udelay(20);
}
static void cls_copy_data_from_queue_to_uart(struct channel_t *ch)