genericserial: remove bogus optimisation check and dead code paths (35426128) · Commits · 戴 / test

drivers/char/generic_serial.c

+3 −117

Original line number	Diff line number	Diff line
		@@ -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");

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