register_fd() bugfix.

[lcr.git] / mISDN.cpp

diff --git a/mISDN.cpp b/mISDN.cpp
index 3e7751e..7be3d4f 100644 (file)
--- a/mISDN.cpp
+++ b/mISDN.cpp
@@ -82,7 +82,7 @@ int mISDN_initialize(void)
 
        if (pipe(upqueue_pipe) < 0)
                FATAL("Failed to open pipe\n");
-       memset(&upqueue_fd, 0, sizeof(upqueue_fd.fd));
+       memset(&upqueue_fd, 0, sizeof(upqueue_fd));
        upqueue_fd.fd = upqueue_pipe[0];
        register_fd(&upqueue_fd, LCR_FD_READ, mISDN_upqueue, NULL, 0);
 
@@ -1834,8 +1834,11 @@ static int mISDN_upqueue(struct lcr_fd *fd, unsigned int what, void *instance, i
        char byte;
 
        /* unset global semaphore */
-       read(fd->fd, &byte, 1);
        upqueue_avail = 0;
+       // with a very small incident, upqueue_avail may be set by mISDN thread and
+       // another byte may be sent to the pipe, which causes a call to this function
+       // again with nothing in the upqueue. this is no problem.
+       read(fd->fd, &byte, 1);
 
        /* process all ports */
        mISDNport = mISDNport_first;
@@ -2060,6 +2063,9 @@ int do_layer3(struct mlayer3 *ml3, unsigned int cmd, unsigned int pid, struct l3
        l3m->pid = pid;
        mqueue_tail(&mISDNport->upqueue, mb);
        if (!upqueue_avail) {
+               // multiple threads may cause multiple calls of this section, but this
+               // results only in multiple processing of the upqueue read.
+               // this is no problem.
                upqueue_avail = 1;
                char byte = 0;
                write(upqueue_pipe[1], &byte, 1);