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Commit e8684c88 authored by Alexey Khoroshilov's avatar Alexey Khoroshilov Committed by David S. Miller
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irda: ali-ircc: Fix deadlock in ali_ircc_sir_change_speed() 



ali_ircc_sir_change_speed() is always called with self->lock held,
so acquiring the lock inside it leads to unavoidable deadlock.

Call graph:
ali_ircc_sir_change_speed() is called from ali_ircc_change_speed()
  ali_ircc_fir_hard_xmit() under spin_lock_irqsave(&self->lock, flags);
  ali_ircc_sir_hard_xmit() under spin_lock_irqsave(&self->lock, flags);
  ali_ircc_net_ioctl() under spin_lock_irqsave(&self->lock, flags);
  ali_ircc_dma_xmit_complete()
    ali_ircc_fir_interrupt()
      ali_ircc_interrupt() under spin_lock(&self->lock);
  ali_ircc_sir_write_wakeup()
    ali_ircc_sir_interrupt()
      ali_ircc_interrupt() under spin_lock(&self->lock);

The patch removes spin_lock/unlock from ali_ircc_sir_change_speed().

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: default avatarAlexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 38c089d1

drivers/net/irda/ali-ircc.c

+0 −6
Original line number Diff line number Diff line
@@ -1031,7 +1031,6 @@ static void ali_ircc_fir_change_speed(struct ali_ircc_cb *priv, __u32 baud) 
static void ali_ircc_sir_change_speed(struct ali_ircc_cb *priv, __u32 speed)

{

	struct ali_ircc_cb *self = priv;

	unsigned long flags;

	int iobase; 

	int fcr;    /* FIFO control reg */

	int lcr;    /* Line control reg */
@@ -1061,8 +1060,6 @@ static void ali_ircc_sir_change_speed(struct ali_ircc_cb *priv, __u32 speed) 
	/* Update accounting for new speed */

	self->io.speed = speed;



	spin_lock_irqsave(&self->lock, flags);



	divisor = 115200/speed;

	

	fcr = UART_FCR_ENABLE_FIFO;
@@ -1089,9 +1086,6 @@ static void ali_ircc_sir_change_speed(struct ali_ircc_cb *priv, __u32 speed) 
	/* without this, the connection will be broken after come back from FIR speed,

	   but with this, the SIR connection is harder to established */

	outb((UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2), iobase+UART_MCR);

	

	spin_unlock_irqrestore(&self->lock, flags);

	

}



static void ali_ircc_change_dongle_speed(struct ali_ircc_cb *priv, int speed)