29bcde7ad8ee7b1ae4595f85fdfb03065f433089

There had been a race condition in there for a rather long while,
I've finaly tracked it down to a small idiotic change of trying to
flush a buffer from the wrong thread.
Removing that flush makes it works properly as intended, without the
mutex.

Signed-off-by: Michel Pollet <buserror@gmail.com>

diff --git a/examples/parts/uart_pty.c b/examples/parts/uart_pty.c
index cbdedbc3f6914adf34a27af2a1661dab2e145350..ef881275acf971d57c970039da3e044b84e2200f 100644 (file)
--- a/examples/parts/uart_pty.c
+++ b/examples/parts/uart_pty.c
@@ -71,8 +71,9 @@ uart_pty_flush_incoming(
                uart_pty_t * p)
 {
        while (p->xon && !uart_pty_fifo_isempty(&p->pty.out)) {
+               TRACE(int r = p->pty.out.read;)
                uint8_t byte = uart_pty_fifo_read(&p->pty.out);
-               TRACE(printf("uart_pty_flush_incoming send %02x\n", byte);)
+               TRACE(printf("uart_pty_flush_incoming send r %03d:%02x\n", r, byte);)
                avr_raise_irq(p->irq + IRQ_UART_PTY_BYTE_OUT, byte);
 
                if (p->tap.s) {
@@ -159,17 +160,22 @@ uart_pty_thread(
 
                for (int ti = 0; ti < 2; ti++) if (p->port[ti].s) {
                        if (FD_ISSET(p->port[ti].s, &read_set)) {
-                               ssize_t r = read(p->port[ti].s, p->port[ti].buffer, sizeof(p->port[ti].buffer)-1);
+                               ssize_t r = read(p->port[ti].s, p->port[ti].buffer,
+                                                                       sizeof(p->port[ti].buffer)-1);
                                p->port[ti].buffer_len = r;
                                p->port[ti].buffer_done = 0;
-                               TRACE(hdump("pty recv", p->port[ti].buffer, r);)
+                               TRACE(if (!p->port[ti].tap) hdump("pty recv", p->port[ti].buffer, r);)
                        }
                        if (p->port[ti].buffer_done < p->port[ti].buffer_len) {
                                // write them in fifo
                                while (p->port[ti].buffer_done < p->port[ti].buffer_len &&
-                                               !uart_pty_fifo_isfull(&p->port[ti].out))
+                                               !uart_pty_fifo_isfull(&p->port[ti].out)) {
+                                       int index = p->port[ti].buffer_done++;
+                                       TRACE(int wi = p->port[ti].out.write;)
                                        uart_pty_fifo_write(&p->port[ti].out,
-                                                       p->port[ti].buffer[p->port[ti].buffer_done++]);
+                                                       p->port[ti].buffer[index]);
+                                       TRACE(printf("w %3d:%02x\n", wi, p->port[ti].buffer[index]);)
+                               }
                        }
                        if (FD_ISSET(p->port[ti].s, &write_set)) {
                                uint8_t buffer[512];
@@ -180,10 +186,13 @@ uart_pty_thread(
                                        *dst++ = uart_pty_fifo_read(&p->port[ti].in);
                                size_t len = dst - buffer;
                                TRACE(size_t r =) write(p->port[ti].s, buffer, len);
-                               TRACE(hdump("pty send", buffer, r);)
+                               TRACE(if (!p->port[ti].tap) hdump("pty send", buffer, r);)
                        }
                }
-               uart_pty_flush_incoming(p);
+               /* DO NOT call this, this create a concurency issue with the
+                * FIFO that can't be solved cleanly with a memory barrier
+                       uart_pty_flush_incoming(p);
+                 */
        }
        return NULL;
 }