lkml.org 
[lkml]   [2015]   [Sep]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] irda: ali-ircc: Fix deadlock in ali_ircc_sir_change_speed()
Date
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>
---
drivers/net/irda/ali-ircc.c | 6 ------
1 file changed, 6 deletions(-)

diff --git a/drivers/net/irda/ali-ircc.c b/drivers/net/irda/ali-ircc.c
index 58ae11a14bb6..64bb44d5d867 100644
--- a/drivers/net/irda/ali-ircc.c
+++ b/drivers/net/irda/ali-ircc.c
@@ -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)
--
1.9.1


\
 
 \ /
  Last update: 2015-09-11 23:41    [W:0.097 / U:1.308 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site