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SubjectRe: [PATCH 2/5] use mutex instead of semaphore in the USB gadget serial driver
Date
On Friday 13 July 2007, Matthias Kaehlcke wrote:
> The USB gadget serial driver uses a semaphore as mutex. Use the
> mutex API instead of the (binary) semaphore.
>
> Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>

ACK (and thanks)

>
> --
>
> diff --git a/drivers/usb/gadget/serial.c b/drivers/usb/gadget/serial.c
> index dd33ff0..4192d24 100644
> --- a/drivers/usb/gadget/serial.c
> +++ b/drivers/usb/gadget/serial.c
> @@ -33,6 +33,7 @@
> #include <linux/device.h>
> #include <linux/tty.h>
> #include <linux/tty_flip.h>
> +#include <linux/mutex.h>
>
> #include <asm/byteorder.h>
> #include <asm/io.h>
> @@ -258,7 +259,7 @@ static const char *EP_IN_NAME;
> static const char *EP_OUT_NAME;
> static const char *EP_NOTIFY_NAME;
>
> -static struct semaphore gs_open_close_sem[GS_NUM_PORTS];
> +static struct mutex gs_open_close_lock[GS_NUM_PORTS];
>
> static unsigned int read_q_size = GS_DEFAULT_READ_Q_SIZE;
> static unsigned int write_q_size = GS_DEFAULT_WRITE_Q_SIZE;
> @@ -595,7 +596,7 @@ static int __init gs_module_init(void)
> tty_set_operations(gs_tty_driver, &gs_tty_ops);
>
> for (i=0; i < GS_NUM_PORTS; i++)
> - sema_init(&gs_open_close_sem[i], 1);
> + mutex_init(&gs_open_close_lock[i]);
>
> retval = tty_register_driver(gs_tty_driver);
> if (retval) {
> @@ -635,7 +636,7 @@ static int gs_open(struct tty_struct *tty, struct file *file)
> struct gs_port *port;
> struct gs_dev *dev;
> struct gs_buf *buf;
> - struct semaphore *sem;
> + struct mutex *mtx;
> int ret;
>
> port_num = tty->index;
> @@ -656,10 +657,10 @@ static int gs_open(struct tty_struct *tty, struct file *file)
> return -ENODEV;
> }
>
> - sem = &gs_open_close_sem[port_num];
> - if (down_interruptible(sem)) {
> + mtx = &gs_open_close_lock[port_num];
> + if (mutex_lock_interruptible(mtx)) {
> printk(KERN_ERR
> - "gs_open: (%d,%p,%p) interrupted waiting for semaphore\n",
> + "gs_open: (%d,%p,%p) interrupted waiting for mutex\n",
> port_num, tty, file);
> return -ERESTARTSYS;
> }
> @@ -754,12 +755,12 @@ static int gs_open(struct tty_struct *tty, struct file *file)
>
> exit_unlock_port:
> spin_unlock_irqrestore(&port->port_lock, flags);
> - up(sem);
> + mutex_unlock(mtx);
> return ret;
>
> exit_unlock_dev:
> spin_unlock_irqrestore(&dev->dev_lock, flags);
> - up(sem);
> + mutex_unlock(mtx);
> return ret;
>
> }
> @@ -781,7 +782,7 @@ exit_unlock_dev:
> static void gs_close(struct tty_struct *tty, struct file *file)
> {
> struct gs_port *port = tty->driver_data;
> - struct semaphore *sem;
> + struct mutex *mtx;
>
> if (port == NULL) {
> printk(KERN_ERR "gs_close: NULL port pointer\n");
> @@ -790,8 +791,8 @@ static void gs_close(struct tty_struct *tty, struct file *file)
>
> gs_debug("gs_close: (%d,%p,%p)\n", port->port_num, tty, file);
>
> - sem = &gs_open_close_sem[port->port_num];
> - down(sem);
> + mtx = &gs_open_close_lock[port->port_num];
> + mutex_lock(mtx);
>
> spin_lock_irq(&port->port_lock);
>
> @@ -846,7 +847,7 @@ static void gs_close(struct tty_struct *tty, struct file *file)
>
> exit:
> spin_unlock_irq(&port->port_lock);
> - up(sem);
> + mutex_unlock(mtx);
> }
>
> /*
>
> --
> Matthias Kaehlcke
> Linux Application Developer
> Barcelona
>
> If liberty means anything at all, it means the
> right to tell people what they do not want to hear
> (George Orwell)
> .''`.
> using free software / Debian GNU/Linux | http://debian.org : :' :
> `. `'`
> gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `-
>


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