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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: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexey Khoroshilov 2015-09-12 00:34:48 +03:00 committed by David S. Miller
parent 38c089d1d8
commit e8684c8877
1 changed files with 0 additions and 6 deletions
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6
drivers/net/irda/ali-ircc.c
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@ -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)