#include <infiniband/umad.h> int umad_poll(int portid, int timeout_ms);
umad_poll() waits up to timeout_ms milliseconds for a packet to be received from the port specified by portid. Once a packet is ready to be read, the function returns 0. After that the packet can be read using umad_recv(). Otherwise, -ETIMEDOUT is returned. Note that successfully polling a port does not guarantee that the subsequent umad_recv() will be non blocking when several threads are using the same port. Instead, use a timeout_ms parameter of zero to umad_recv() to ensure a non-blocking read.
umad_poll() returns 0 on success, and a negative value on error as follows:
-EINVAL invalid port handle or agentid
-ETIMEDOUT poll operation timed out
-EIO poll operation failed
Hal Rosenstock <email@example.com>