n_tty: Remove overflow tests from receive_buf() path

Always pre-figure the space available in the read_buf and limit
the inbound receive request to that amount.

For compatibility reasons with the non-flow-controlled interface,
n_tty_receive_buf() will continue filling read_buf until all data
has been received or receive_room() returns 0.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index adc06af3a0754f3f3546b7b31d3559e13e4c30b2..f66d95f949d198acc6f251e25a4562adbe494503 100644 (file)
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -316,12 +316,9 @@ static inline void n_tty_check_unthrottle(struct tty_struct *tty)
  *     not active.
  */
 
-static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
+static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)
 {
-       if (read_cnt(ldata) < N_TTY_BUF_SIZE) {
-               *read_buf_addr(ldata, ldata->read_head) = c;
-               ldata->read_head++;
-       }
+       *read_buf_addr(ldata, ldata->read_head++) = c;
 }
 
 /**
@@ -1333,11 +1330,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
                        return;
                }
                if (c == '\n') {
-                       if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {
-                               if (L_ECHO(tty))
-                                       process_output('\a', tty);
-                               return;
-                       }
                        if (L_ECHO(tty) || L_ECHONL(tty)) {
                                echo_char_raw('\n', ldata);
                                commit_echoes(tty);
@@ -1345,8 +1337,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
                        goto handle_newline;
                }
                if (c == EOF_CHAR(tty)) {
-                       if (read_cnt(ldata) >= N_TTY_BUF_SIZE)
-                               return;
                        c = __DISABLED_CHAR;
                        goto handle_newline;
                }
@@ -1354,11 +1344,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
                    (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
                        parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
                                 ? 1 : 0;
-                       if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {
-                               if (L_ECHO(tty))
-                                       process_output('\a', tty);
-                               return;
-                       }
                        /*
                         * XXX are EOL_CHAR and EOL2_CHAR echoed?!?
                         */
@@ -1388,12 +1373,6 @@ handle_newline:
        }
 
        parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-       if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
-               /* beep if no space */
-               if (L_ECHO(tty))
-                       process_output('\a', tty);
-               return;
-       }
        if (L_ECHO(tty)) {
                finish_erasing(ldata);
                if (c == '\n')
@@ -1432,14 +1411,6 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
                        start_tty(tty);
                        process_echoes(tty);
                }
-
-               parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
-               if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {
-                       /* beep if no space */
-                       if (L_ECHO(tty))
-                               process_output('\a', tty);
-                       return;
-               }
                if (L_ECHO(tty)) {
                        finish_erasing(ldata);
                        /* Record the column of first canon char. */
@@ -1448,6 +1419,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
                        echo_char(c, tty);
                        commit_echoes(tty);
                }
+               parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
                if (parmrk)
                        put_tty_queue(c, ldata);
                put_tty_queue(c, ldata);
@@ -1476,13 +1448,6 @@ n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
                        start_tty(tty);
                        process_echoes(tty);
                }
-
-               if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - 1)) {
-                       /* beep if no space */
-                       if (L_ECHO(tty))
-                               process_output('\a', tty);
-                       return;
-               }
                if (L_ECHO(tty)) {
                        finish_erasing(ldata);
                        /* Record the column of first canon char. */
@@ -1691,8 +1656,23 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
 static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
                              char *fp, int count)
 {
+       int room, n;
+
        down_read(&tty->termios_rwsem);
-       __receive_buf(tty, cp, fp, count);
+
+       while (1) {
+               room = receive_room(tty);
+               n = min(count, room);
+               if (!n)
+                       break;
+               __receive_buf(tty, cp, fp, n);
+               cp += n;
+               if (fp)
+                       fp += n;
+               count -= n;
+       }
+
+       tty->receive_room = room;
        n_tty_check_throttle(tty);
        up_read(&tty->termios_rwsem);
 }
@@ -1701,22 +1681,31 @@ static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp,
                              char *fp, int count)
 {
        struct n_tty_data *ldata = tty->disc_data;
-       int room;
+       int room, n, rcvd = 0;
 
        down_read(&tty->termios_rwsem);
 
-       tty->receive_room = room = receive_room(tty);
-       if (!room)
-               ldata->no_room = 1;
-       count = min(count, room);
-       if (count) {
-               __receive_buf(tty, cp, fp, count);
-               n_tty_check_throttle(tty);
+       while (1) {
+               room = receive_room(tty);
+               n = min(count, room);
+               if (!n) {
+                       if (!room)
+                               ldata->no_room = 1;
+                       break;
+               }
+               __receive_buf(tty, cp, fp, n);
+               cp += n;
+               if (fp)
+                       fp += n;
+               count -= n;
+               rcvd += n;
        }
 
+       tty->receive_room = room;
+       n_tty_check_throttle(tty);
        up_read(&tty->termios_rwsem);
 
-       return count;
+       return rcvd;
 }
 
 int is_ignored(int sig)