Hi - To clarify, more specifically select() returns a positive value, and a subsequent call to FD_ISSET() returns TRUE for one of the sockets the app is listening on. Then, app calls recvfrom() which returns (sometimes) -1. Problem occurs sporadically...I'm seeing it every hundred or so packets at the moment, but it varies. Thanks, Gill -----Original Message----- From: linux-mips-bounce@xxxxxxxxxxxxxx [mailto:linux-mips-bounce@xxxxxxxxxxxxxx] On Behalf Of Jan-Benedict Glaw Sent: 22 May 2004 17:07 To: linux-mips@xxxxxxxxxxxxxx Subject: Re: Socket problem? On Sat, 2004-05-22 09:02:48 +0100, Gill <gill.robles@xxxxxxxxxxxxxx> wrote in message <000001c43fd3$2c25a350$2000a8c0@gillpc>: > Hi - > > Has anyone come across a socket problem where the user app calls > select() on a set of sockets, which returns, indicating that data is > waiting...then subsequent recvfrom() call returns -1 indicating that > there's nothing there?? Read the select() manpage again. Upon successful return, it's guaranteed that the very next read() on a file descriptor contained in the result set won't block. Typically, it's the case after data arrived, but returning -1 *immediately* (with no blocking) is okay, too. > I'm using linux v2.4.2, IPv4, and the ethernet driver is pcnet32. > We're receiving a UDP stream. Quite aged version, though perfectly correct on select() behaviour. > I'm trying to check for dropped packets. /proc/net/snmp indicates a > number of UDP InErrors (~1 per second). However, not yet sure whether > this is a consequence of the problem above, or cause of it. Neither - nor. You've got a small thinko in your application. Albeit that: update your kernel version... It most probably contains a number of known root exploits. MfG, JBG -- Jan-Benedict Glaw jbglaw@xxxxxxxxxx . +49-172-7608481 "Eine Freie Meinung in einem Freien Kopf | Gegen Zensur | Gegen Krieg fuer einen Freien Staat voll Freier Bürger" | im Internet! | im Irak! ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));
