Skip to content

Commit

Permalink
irda: ali-ircc: Fix deadlock in ali_ircc_sir_change_speed()
Browse files Browse the repository at this point in the history
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>
  • Loading branch information
Alexey Khoroshilov authored and David S. Miller committed Sep 11, 2015
1 parent 38c089d commit e8684c8
Showing 1 changed file with 0 additions and 6 deletions.
6 changes: 0 additions & 6 deletions drivers/net/irda/ali-ircc.c
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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;
Expand All @@ -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)
Expand Down

0 comments on commit e8684c8

Please sign in to comment.