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serial-uartlite: fix missing locking in isr 

The uartlite driver suffers from missing/duplicate/corrupted character
data when the interrupt handler runs concurrently with access to the
device from another cpu. Take the port spinlock to exclude concurrent
access.

Signed-off-by: Rich Felker <dalias@libc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rich Felker 2016-01-08 15:33:50 -05:00 committed by Greg Kroah-Hartman
parent 7cdcc29e49
commit 9e370d2c9f
1 changed files with 4 additions and 0 deletions
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4
drivers/tty/serial/uartlite.c
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@ -194,7 +194,9 @@ static irqreturn_t ulite_isr(int irq, void *dev_id)
{
struct uart_port *port = dev_id;
int busy, n = 0;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
do {
int stat = uart_in32(ULITE_STATUS, port);
busy = ulite_receive(port, stat);
@ -202,6 +204,8 @@ static irqreturn_t ulite_isr(int irq, void *dev_id)
n++;
} while (busy);
spin_unlock_irqrestore(&port->lock, flags);
/* work done? */
if (n > 1) {
tty_flip_buffer_push(&port->state->port);