From 9cf6c1d80c2f159dbb69967fbe934bf6de73c9e8 Mon Sep 17 00:00:00 2001 From: Max Krummenacher Date: Tue, 5 Aug 2025 09:35:06 +0200 Subject: [PATCH 2/2] linux-serial-test.c: fix potential hang in while loop process_read_data() assumes that we can always wait for reception of 1024 chars. However that is not true if one sets the number of chars with the '-w' cmdline parameter or chars are lost. Maybe there are other reasons. Replace the magic number of 1024 by calculating the number of expected chars from _cl_tx_bytes. Brake a possible infinite while loop by adding a timeout to the loop calculated from the expected chars times chartime. Upstream-Status: Submitted [https://github.com/cbrake/linux-serial-test/pull/61/] Fixes: 7fd1057f8a95 ("Add loop to read all data in rcv buffer") Signed-off-by: Max Krummenacher Signed-off-by: Emanuele Ghidoli --- linux-serial-test.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/linux-serial-test.c b/linux-serial-test.c index c2c8882d601b..294f53882570 100644 --- a/linux-serial-test.c +++ b/linux-serial-test.c @@ -543,8 +543,13 @@ static unsigned char next_count_value(unsigned char c) static void process_read_data(void) { unsigned char rb[1024]; + int loopcounter = 0; int actual_read_count = 0; - while (actual_read_count < 1024) { + int expected_read_count = _cl_tx_bytes == 0 ? 1024 : _cl_tx_bytes; + /* time for one char at current baudrate in us */ + int chartime = 1000000 * (8 + _cl_parity + 1 + _cl_2_stop_bit) / _cl_baud; + + while (actual_read_count < expected_read_count) { int c = read(_fd, &rb, sizeof(rb)); if (c > 0) { if (_cl_rx_dump) { @@ -577,7 +582,12 @@ static void process_read_data(void) if (errno != EAGAIN) { perror("read failed"); } - continue; // Retry the read + + if (loopcounter++ < expected_read_count) { + usleep(chartime); + continue; // Retry the read + } + break; } else { break; } -- 2.43.0