lkml.org 
[lkml]   [2010]   [Jun]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 05/11] TTY/n_gsm: potential double lock
Date
From: Dan Carpenter <error27@gmail.com>

In gsm_dlci_data_kick() we call gsm_dlci_data_sweep() with the
"gsm->tx_lock" held so we can't lock it again inside
gsm_dlci_data_sweep(). I removed that lock from and added one to
gsmld_write_wakeup() instead. The sweep function is only called from
those two places.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/char/n_gsm.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/char/n_gsm.c b/drivers/char/n_gsm.c
index c4161d5..e4089c4 100644
--- a/drivers/char/n_gsm.c
+++ b/drivers/char/n_gsm.c
@@ -904,9 +904,7 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
int len;
/* Priority ordering: We should do priority with RR of the groups */
int i = 1;
- unsigned long flags;

- spin_lock_irqsave(&gsm->tx_lock, flags);
while (i < NUM_DLCI) {
struct gsm_dlci *dlci;

@@ -927,7 +925,6 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
if (len == 0)
i++;
}
- spin_unlock_irqrestore(&gsm->tx_lock, flags);
}

/**
@@ -2230,12 +2227,16 @@ static int gsmld_open(struct tty_struct *tty)
static void gsmld_write_wakeup(struct tty_struct *tty)
{
struct gsm_mux *gsm = tty->disc_data;
+ unsigned long flags;

/* Queue poll */
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
gsm_data_kick(gsm);
- if (gsm->tx_bytes < TX_THRESH_LO)
+ if (gsm->tx_bytes < TX_THRESH_LO) {
+ spin_lock_irqsave(&gsm->tx_lock, flags);
gsm_dlci_data_sweep(gsm);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ }
}

/**
--
1.7.1


\
 
 \ /
  Last update: 2010-06-04 22:53    [W:0.077 / U:0.628 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site