On Tue, 2012-02-28 at 16:15 +0100, Ronald Wahl wrote: > >> Currently I implemented a heuristic that checks if some minimum space > >> (currently 256 bytes) is still free _after_ adding a BSS and otherwise > >> return -E2BIG so the user space can provide a larger buffer but this is > >> a crappy hack. > >> > >> Can the code be changed in some way to more reliably detect if some data > >> did not fit into the buffer and report this to user space? > > > > Unfortunately not. The maximum buffer size userspace can provide is > > limited to 64k. In busy environments, this size can be exceeded. As a > > result, if we do this, you can't get *any* scan results in such > > environments. I believe the current code is almost the best we can do > > for wireless extensions, but it may be possible to implement never > > truncating a single BSS entry. > > My problem is not that the scan results are larger than 64k. The user > space is coded so that it provides a small buffer that is doubled in > size until the data fits into the buffer. But the kernel code does not > always detect the case that the buffer is almost full and just starts > skipping some data without notifying user space with E2BIG. Ok. Yes, this could be fixed by making sure that a single BSS is atomically written or not written -- probably simply by rolling back at the end of the function if it didn't fit and returning an error etc. If you wanted to work on this, I'd review & accept the patch, but I have no intention whatsoever to do this myself :-) johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
