kernel/drivers/tty/n_tty.c, branch linux-6.9.y

tty: n_tty: Fix buffer offsets when lookahead is used

2024-06-21T12:40:12Z

commit b19ab7ee2c4c1ec5f27c18413c3ab63907f7d55c upstream. When lookahead has "consumed" some characters (la_count > 0), n_tty_receive_buf_standard() and n_tty_receive_buf_closing() for characters beyond the la_count are given wrong cp/fp offsets which leads to duplicating and losing some characters. If la_count > 0, correct buffer pointers and make count consistent too (the latter is not strictly necessary to fix the issue but seems more logical to adjust all variables immediately to keep state consistent). Reported-by: Vadym Krevs Fixes: 6bb6fa6908eb ("tty: Implement lookahead to process XON/XOFF timely") Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218834 Tested-by: Vadym Krevs Cc: stable@vger.kernel.org Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20240514140429.12087-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

tty: invert return values of tty_{,un}throttle_safe()

2023-10-03T12:31:15Z

If tty_{,un}throttle_safe() returned true on success (similar to *_trylock()), it would make the conditions in callers more obvious. So perform the switch to these inverted values (and fix the callers). Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230919085156.1578-8-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: use do-while in n_tty_check_{,un}throttle()

2023-10-03T12:31:15Z

This change gets rid of the complicated exit from the loops. It can be done much easier using do-while loops. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230919085156.1578-6-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: invert the condition in copy_from_read_buf()

2023-10-03T12:31:15Z

Make "no numbers available" a fast quit from the function. And do the heavy work outside the 'if'. This makes the code more understandable and conforming to the common kernel coding style. Signed-off-by: "Jiri Slaby (SUSE)" Reviewed-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20230919085156.1578-5-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: use min3() in copy_from_read_buf()

2023-10-03T12:31:15Z

n is a minimum of: * available chars in the ring buffer * available chars in the ring buffer till the end of the ring buffer * requested number (*nr) We can use min3() for that instead of two min()s. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230919085156.1578-4-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: rename and retype 'retval' in n_tty_ioctl()

2023-10-03T12:31:15Z

The value stored to the current 'retval' is number of characters. It is both obtained and put to user as unsigned. So make its type unsigned. And provided it's not a "return value" per se, rename it to 'num'. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230919085156.1578-3-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: use 'retval' instead of 'c'

2023-10-03T12:31:15Z

In n_tty_read(), there is a separate int variable 'c' and is used only to hold an int value returned from job_control(). There is also a 'retval' variable typed ssize_t. So drop this single occurrence of 'c' and reuse 'retval' which is used on all other places to hold the value returned from n_tty_read(). Note that 'retval' needs not be initialized now. Drop that. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230919085156.1578-2-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: deduplicate copy code in n_tty_receive_buf_real_raw()

2023-08-27T09:46:52Z

The code is duplicated to perform the copy twice -- to handle buffer wrap-around. Instead of the duplication, roll this into the loop. (And add some blank lines around to have the code a bit more readable.) Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230827074147.2287-15-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: extract ECHO_OP processing to a separate function

2023-08-27T09:46:52Z

__process_echoes() contains ECHO_OPs processing. It is stuffed in a while loop and the whole function is barely readable. Separate it to a new function: n_tty_process_echo_ops(). Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230827074147.2287-14-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: n_tty: unify counts to size_t

2023-08-27T09:46:52Z

Some count types are already 'size_t' for a long time. Some were switched to 'size_t' recently. Unify the rest with those now. This allows for some min_t()s to become min()s. And make one min() an explicit min_t() as we are comparing signed 'room' to unsigned 'count'. Signed-off-by: "Jiri Slaby (SUSE)" Link: https://lore.kernel.org/r/20230827074147.2287-13-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman