lkml.org 
[lkml]   [2008]   [Mar]   [30]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSun, 30 Mar 2008 13:16:52 +0100
FromAlan Cox <>
SubjectRe: [PATCH] ptmx: adding handshake support
On Sun, 30 Mar 2008 14:09:48 +0200
postmaster@van-ginkel.eu wrote:

> This weekend I upgraded my kernel to 2.6.22.5 and tried my patch.
> Unfortunately pty.c seems to be a slightly different, so generated a new
> patch:

Really you want to be working against 2.6.25-rc5-mm1 or later as there
are big changes in the tty layer pending, some of which affect the
locking on stuff like this.

> +struct pty_mcrmsr {> +> +	struct semaphore        sem;            /* locks this structure */

You create a lock but don't use it. Also btw the -mm tty layer has a
ctrl_lock you could use instead.

> +	/* for tiocmget and tiocmset functions */> +> +	int                     msr;            /* MSR shadow */
> +	int                     mcr;            /* MCR shadow */

Could be one value using the existing bit masks.

> +	mcrmsr = kmalloc(sizeof(*mcrmsr), GFP_KERNEL);> +> +	init_MUTEX(&mcrmsr->sem);

Crashes on allocation failure

> +	if (tty->driver_data != NULL) {> +		msr = mcrmsr->msr;> +		mcr = mcrmsr->mcr;> +	}

Always true

> +> +	result = ((mcr & 0x01)  ? TIOCM_DTR  : 0) |  /* DTR is set */
> +		((mcr & 0x02)  ? TIOCM_RTS  : 0) |  /* RTS is set */
> +		((mcr & 0x04)  ? TIOCM_LOOP : 0) |  /* LOOP is set */
> +		((msr & 0x08)  ? TIOCM_CTS  : 0) |  /* CTS is set */
> +		((msr & 0x10)  ? TIOCM_CAR  : 0) |  /* Carrier detect is set*/
> +		((msr & 0x20)  ? TIOCM_RI   : 0) |  /* Ring Indicator is set */
> +		((msr & 0x40)  ? TIOCM_DSR  : 0);   /* DSR is set */

Use the mcr/msr bits as is and you don't need this mess

> +	if (set & TIOCM_DTR)
> +		mcr |= 0x01;
> +	if (set & TIOCM_RTS)
> +		mcr |= 0x02;
> +	if (set & TIOCM_LOOP)

Ditto

> +	/* set the new MCR value in the device */> +> +	if (tty->driver_data != NULL)> +		mcrmsr->mcr=mcr;

That may cause wakeups, open, hangup etc to occur - does that need to be
considered here.

> +	case 0x5426: /* Set all of the handshake line, even the normally  
> read only */

Use a proper value as I said before.





\
 
 \ /
  Last update: 2008-03-30 14:37    [from the cache]
©2003-2008