Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-25 21:51:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

genericserial: remove bogus optimisation check and dead code paths

Browse Source 
We've been using the 'new locking' for a long time now so it seems
pointless keeping the old one around.  Remove it and undo the macros it
uses back into real code for readability.  Remove the bogus 'no termios
change' checks.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Morten Helgesen <morten@sourcepoet.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alan Cox 2007-07-15 23:41:47 -07:00 committed by Linus Torvalds
parent db0ef08efa
commit 35426128ad
1 changed files with 3 additions and 117 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

120
drivers/char/generic_serial.c
View File

@ -43,16 +43,6 @@ static int gs_debug;
#define func_enter() gs_dprintk (GS_DEBUG_FLOW, "gs: enter %s\n", __FUNCTION__)
#define func_exit() gs_dprintk (GS_DEBUG_FLOW, "gs: exit %s\n", __FUNCTION__)
#define NEW_WRITE_LOCKING 1
#if NEW_WRITE_LOCKING
#define DECL /* Nothing */
#define LOCKIT mutex_lock(& port->port_write_mutex);
#define RELEASEIT mutex_unlock(&port->port_write_mutex);
#else
#define DECL unsigned long flags;
#define LOCKIT save_flags (flags);cli ()
#define RELEASEIT restore_flags (flags)
#endif
#define RS_EVENT_WRITE_WAKEUP 1
@ -62,7 +52,6 @@ module_param(gs_debug, int, 0644);
void gs_put_char(struct tty_struct * tty, unsigned char ch)
{
struct gs_port *port;
DECL
func_enter ();
@ -75,11 +64,11 @@ void gs_put_char(struct tty_struct * tty, unsigned char ch)
if (! (port->flags & ASYNC_INITIALIZED)) return;
/* Take a lock on the serial tranmit buffer! */
LOCKIT;
mutex_lock(& port->port_write_mutex);
if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
/* Sorry, buffer is full, drop character. Update statistics???? -- REW */
RELEASEIT;
mutex_unlock(&port->port_write_mutex);
return;
}
@ -87,13 +76,11 @@ void gs_put_char(struct tty_struct * tty, unsigned char ch)
port->xmit_head &= SERIAL_XMIT_SIZE - 1;
port->xmit_cnt++; /* Characters in buffer */
RELEASEIT;
mutex_unlock(&port->port_write_mutex);
func_exit ();
}
#ifdef NEW_WRITE_LOCKING
/*
> Problems to take into account are:
> -1- Interrupts that empty part of the buffer.
@ -166,90 +153,6 @@ int gs_write(struct tty_struct * tty,
func_exit ();
return total;
}
#else
/*
> Problems to take into account are:
> -1- Interrupts that empty part of the buffer.
> -2- page faults on the access to userspace.
> -3- Other processes that are also trying to do a "write".
*/
int gs_write(struct tty_struct * tty,
const unsigned char *buf, int count)
{
struct gs_port *port;
int c, total = 0;
int t;
unsigned long flags;
func_enter ();
/* The standard serial driver returns 0 in this case.
That sounds to me as "No error, I just didn't get to writing any
bytes. Feel free to try again."
The "official" way to write n bytes from buf is:
for (nwritten = 0;nwritten < n;nwritten += rv) {
rv = write (fd, buf+nwritten, n-nwritten);
if (rv < 0) break; // Error: bail out. //
}
which will loop endlessly in this case. The manual page for write
agrees with me. In practise almost everybody writes
"write (fd, buf,n);" but some people might have had to deal with
incomplete writes in the past and correctly implemented it by now...
*/
if (!tty) return -EIO;
port = tty->driver_data;
if (!port || !port->xmit_buf)
return -EIO;
local_save_flags(flags);
while (1) {
cli();
c = count;
/* This is safe because we "OWN" the "head". Noone else can
change the "head": we own the port_write_mutex. */
/* Don't overrun the end of the buffer */
t = SERIAL_XMIT_SIZE - port->xmit_head;
if (t < c) c = t;
/* This is safe because the xmit_cnt can only decrease. This
would increase "t", so we might copy too little chars. */
/* Don't copy past the "head" of the buffer */
t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
if (t < c) c = t;
/* Can't copy more? break out! */
if (c <= 0) {
local_restore_flags(flags);
break;
}
memcpy(port->xmit_buf + port->xmit_head, buf, c);
port->xmit_head = ((port->xmit_head + c) &
(SERIAL_XMIT_SIZE-1));
port->xmit_cnt += c;
local_restore_flags(flags);
buf += c;
count -= c;
total += c;
}
if (port->xmit_cnt &&
!tty->stopped &&
!tty->hw_stopped &&
!(port->flags & GS_TX_INTEN)) {
port->flags |= GS_TX_INTEN;
port->rd->enable_tx_interrupts (port);
}
func_exit ();
return total;
}
#endif
@ -737,23 +640,6 @@ void gs_set_termios (struct tty_struct * tty,
gs_dprintk (GS_DEBUG_TERMIOS, "termios structure (%p):\n", tiosp);
}
/* This is an optimization that is only allowed for dumb cards */
/* Smart cards require knowledge of iflags and oflags too: that
might change hardware cooking mode.... */
if (old_termios) {
if( (tiosp->c_iflag == old_termios->c_iflag)
&& (tiosp->c_oflag == old_termios->c_oflag)
&& (tiosp->c_cflag == old_termios->c_cflag)
&& (tiosp->c_lflag == old_termios->c_lflag)
&& (tiosp->c_line == old_termios->c_line)
&& (memcmp(tiosp->c_cc, old_termios->c_cc, NCC) == 0)) {
gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: optimized away\n");
return /* 0 */;
}
} else
gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: no old_termios: "
"no optimization\n");
if(old_termios && (gs_debug & GS_DEBUG_TERMIOS)) {
if(tiosp->c_iflag != old_termios->c_iflag) printk("c_iflag changed\n");
if(tiosp->c_oflag != old_termios->c_oflag) printk("c_oflag changed\n");