Commit 72250d44 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by David S. Miller
Browse files

i4l: kill big kernel lock 



The isdn4linux driver uses the big kernel lock only
to serialize access to a few fields in its own
modem_info structure.

The easiest replacement is a driver-wide mutex.
More fine-grained locking would be more appropriate
here, but likely harder to implement.

Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: netdev@vger.kernel.org
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0a5f1d47

drivers/isdn/i4l/isdn_tty.c

+6 −5
Original line number Diff line number Diff line
@@ -14,7 +14,7 @@ 
#include <linux/isdn.h>

#include <linux/slab.h>

#include <linux/delay.h>

#include <linux/smp_lock.h>

#include <linux/mutex.h>

#include "isdn_common.h"

#include "isdn_tty.h"

#ifdef CONFIG_ISDN_AUDIO
@@ -28,6 +28,7 @@ 


/* Prototypes */



static DEFINE_MUTEX(modem_info_mutex);

static int isdn_tty_edit_at(const char *, int, modem_info *);

static void isdn_tty_check_esc(const u_char *, u_char, int, int *, u_long *);

static void isdn_tty_modem_reset_regs(modem_info *, int);
@@ -1354,14 +1355,14 @@ isdn_tty_tiocmget(struct tty_struct *tty, struct file *file) 
	if (tty->flags & (1 << TTY_IO_ERROR))

		return -EIO;



	lock_kernel();

	mutex_lock(&modem_info_mutex);

#ifdef ISDN_DEBUG_MODEM_IOCTL

	printk(KERN_DEBUG "ttyI%d ioctl TIOCMGET\n", info->line);

#endif



	control = info->mcr;

	status = info->msr;

	unlock_kernel();

	mutex_unlock(&modem_info_mutex);

	return ((control & UART_MCR_RTS) ? TIOCM_RTS : 0)

	    | ((control & UART_MCR_DTR) ? TIOCM_DTR : 0)

	    | ((status & UART_MSR_DCD) ? TIOCM_CAR : 0)
@@ -1385,7 +1386,7 @@ isdn_tty_tiocmset(struct tty_struct *tty, struct file *file, 
	printk(KERN_DEBUG "ttyI%d ioctl TIOCMxxx: %x %x\n", info->line, set, clear);

#endif



	lock_kernel();

	mutex_lock(&modem_info_mutex);

	if (set & TIOCM_RTS)

		info->mcr |= UART_MCR_RTS;

	if (set & TIOCM_DTR) {
@@ -1407,7 +1408,7 @@ isdn_tty_tiocmset(struct tty_struct *tty, struct file *file, 
			isdn_tty_modem_hup(info, 1);

		}

	}

	unlock_kernel();

	mutex_unlock(&modem_info_mutex);

	return 0;

}

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