[Bluez-devel] Rfcomm Use Count

Daryl Van Vorst
2004-09-17T00:10:50Z

Marcel,

I have a simple way to reproduce at least part of this bug. I don't have =
an
up-to-date x86 machine to try this on, but I suspect you'll see the same
behaviour:

1. Compile and run the attached code on one machine
2. Connect to it from another machine using: rctest -n -P1 <bd_addr>
3. Hit ctrl-c on rctest
4. Hit ctrl-c on bzt (or whatever you called the compiled code)
5. lsmod and look at the rfcomm use count.

I think the problem stems from rfcomm_cleanup_listen() and
bluez_accept_dequeue(). Bluez_accept_dequeue() won't return the socket =
if it
is in the closed state, and so rfcomm_cleanup_listen() can't fully =
cleanup.

And if accept is called before rfcomm_cleanup_listen(), then (I think) =
the
socket will be unlinked from the accept queue (by accept) but not =
killed,
and so also will not get cleaned up.

Things appear to work if you reverse the order of steps 3 and 4.

I'd send you a patch if I had a simple one, but I don't know what the =
best
approach is. On solution may be to make bluez_accept_dequeue() always =
return
the socket regardless of state and then fix anything that calls
bluez_accept_dequeue() to handle the possibility of a closed socket =
being
returned.

-Daryl.

--- test code below ---
// bzt.c

#include <stdio.h>
#include <errno.h>
#include <sys/socket.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/rfcomm.h>

int main(int argc, char *argv[])
{
struct sockaddr_rc loc_addr;
int s;
=09
if((s =3D socket(PF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM)) < 0) {
printf("Can't create server socket:
%s(%d)\n",strerror(errno), errno);
return -1;
}
=09
loc_addr.rc_family =3D AF_BLUETOOTH;
bacpy(&loc_addr.rc_bdaddr, BDADDR_ANY);
loc_addr.rc_channel =3D 1;
if(bind(s,(struct sockaddr *) &loc_addr, sizeof(loc_addr)) < 0) {
printf("Can't bind %s(%d)\n",strerror(errno), errno);
return -1;
}
=09
if(listen(s,10)) {
printf("Can't listen %s(%d)\n",strerror(errno),errno);
return -1;
}
=09
printf("Listening...\n");
while(1) sleep(999);
=09
return 0;
}

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