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authorJoe Peterson <joe@skyrush.com>2009-01-02 13:43:32 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-02 10:19:37 -0800
commitacc71bbad33478973dbed68ebbc2d76dac9a51bd (patch)
tree6cf78a3f0de9811bdc30739ccd01a4db6c4b3baf /drivers/char/n_tty.c
parenta59c0d6f14315a3f300f6f3786137213727e4c47 (diff)
downloadlinux-linaro-stable-acc71bbad33478973dbed68ebbc2d76dac9a51bd.tar.gz
n_tty: Fix hanfling of buffer full corner cases
Fix the handling of input characters when the tty buffer is full or nearly full. This includes tests that are done in n_tty_receive_char() and handling of PARMRK. Problems with the buffer-full tests done in receive_char() caused characters to be lost at times when the buffer(s) filled. Also, these full conditions would often only be detected with echo on, and PARMRK was not accounted for properly in all cases. One symptom of these problems, in addition to lost characters, was early termination from unix commands like tr and cat when ^Q was used to break from a stopped tty with full buffers (note that breaking out was often previously not possible, due to the pty getting in "gridlock", which will be addressed in another patch). Note space is always reserved at the end of the buffer for a newline (or EOF/EOL) in canonical mode. Signed-off-by: Joe Peterson <joe@skyrush.com> Signed-off-by: Alan Cox <alan@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/n_tty.c')
-rw-r--r--drivers/char/n_tty.c55
1 files changed, 38 insertions, 17 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 30b0426b3788..4b1e96b65ab0 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -1107,6 +1107,7 @@ static inline void n_tty_receive_parity_error(struct tty_struct *tty,
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
{
unsigned long flags;
+ int parmrk;
if (tty->raw) {
put_tty_queue(c, tty);
@@ -1144,21 +1145,24 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
*/
if (!test_bit(c, tty->process_char_map) || tty->lnext) {
tty->lnext = 0;
- if (L_ECHO(tty)) {
- finish_erasing(tty);
- if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
- /* beep if no space */
+ parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
+ if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
+ /* beep if no space */
+ if (L_ECHO(tty)) {
echo_char_raw('\a', tty);
process_echoes(tty);
- return;
}
+ return;
+ }
+ if (L_ECHO(tty)) {
+ finish_erasing(tty);
/* Record the column of first canon char. */
if (tty->canon_head == tty->read_head)
echo_set_canon_col(tty);
echo_char(c, tty);
process_echoes(tty);
}
- if (I_PARMRK(tty) && c == (unsigned char) '\377')
+ if (parmrk)
put_tty_queue(c, tty);
put_tty_queue(c, tty);
return;
@@ -1250,15 +1254,22 @@ send_signal:
return;
}
if (c == '\n') {
- if (L_ECHO(tty) || L_ECHONL(tty)) {
- if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
+ if (tty->read_cnt >= N_TTY_BUF_SIZE) {
+ if (L_ECHO(tty)) {
echo_char_raw('\a', tty);
+ process_echoes(tty);
+ }
+ return;
+ }
+ if (L_ECHO(tty) || L_ECHONL(tty)) {
echo_char_raw('\n', tty);
process_echoes(tty);
}
goto handle_newline;
}
if (c == EOF_CHAR(tty)) {
+ if (tty->read_cnt >= N_TTY_BUF_SIZE)
+ return;
if (tty->canon_head != tty->read_head)
set_bit(TTY_PUSH, &tty->flags);
c = __DISABLED_CHAR;
@@ -1266,12 +1277,19 @@ send_signal:
}
if ((c == EOL_CHAR(tty)) ||
(c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {
+ parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))
+ ? 1 : 0;
+ if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk)) {
+ if (L_ECHO(tty)) {
+ echo_char_raw('\a', tty);
+ process_echoes(tty);
+ }
+ return;
+ }
/*
* XXX are EOL_CHAR and EOL2_CHAR echoed?!?
*/
if (L_ECHO(tty)) {
- if (tty->read_cnt >= N_TTY_BUF_SIZE-1)
- echo_char_raw('\a', tty);
/* Record the column of first canon char. */
if (tty->canon_head == tty->read_head)
echo_set_canon_col(tty);
@@ -1282,7 +1300,7 @@ send_signal:
* XXX does PARMRK doubling happen for
* EOL_CHAR and EOL2_CHAR?
*/
- if (I_PARMRK(tty) && c == (unsigned char) '\377')
+ if (parmrk)
put_tty_queue(c, tty);
handle_newline:
@@ -1299,14 +1317,17 @@ handle_newline:
}
}
- if (L_ECHO(tty)) {
- finish_erasing(tty);
- if (tty->read_cnt >= N_TTY_BUF_SIZE-1) {
- /* beep if no space */
+ parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;
+ if (tty->read_cnt >= (N_TTY_BUF_SIZE - parmrk - 1)) {
+ /* beep if no space */
+ if (L_ECHO(tty)) {
echo_char_raw('\a', tty);
process_echoes(tty);
- return;
}
+ return;
+ }
+ if (L_ECHO(tty)) {
+ finish_erasing(tty);
if (c == '\n')
echo_char_raw('\n', tty);
else {
@@ -1318,7 +1339,7 @@ handle_newline:
process_echoes(tty);
}
- if (I_PARMRK(tty) && c == (unsigned char) '\377')
+ if (parmrk)
put_tty_queue(c, tty);
put_tty_queue(c, tty);