On 29/06/15 09:14, Johannes Berg wrote: > On Sat, 2015-06-27 at 16:34 +0100, Tom Hughes wrote: >> >> Interestingly from what I can see this is trying to create a file >> for the station at a path something like: >> >> ieee80211/phy0/netdev:XXXX/stations/XXXXXX > > indeed. > >> but in my (currently working) boot under 4.0.4 there is no netdev >> directory under phy0 in debugfs... but then maybe that is the problem >> as well if the inode pointer was null? >> > > This is pretty strange - if the dentry pointer (sdata > ->debugfs.subdir_stations) was NULL or an ERR_PTR(), the code would > return pretty much immediately. > > So it looks like that pointer is valid, but it's ->d_inode was NULL? > > I'm not really sure how that could happen. Indeed I'm a bit puzzled... I can't see anything obvious in the kernel logs indicating a problem, but here's a listing of the phy0 directory: [root@gosford]/home/tom# uname -a Linux gosford.compton.nu 4.0.4-301.fc22.i686+PAE #1 SMP Thu May 21 13:27:48 UTC 2015 i686 i686 i386 GNU/Linux [root@gosford]/home/tom# ls /sys/kernel/debug/ieee80211/phy0 ath9k keys rc statistics fragmentation_threshold long_retry_limit reset total_ps_buffered ht40allow_map power rts_threshold user_power hwflags queues short_retry_limit wep_iv with no netdev directory at all. Interestingly I just tried a different machine running on more or less the same kernel with a USB wireless stick and that did get a netdev directory... > Since 4.0.4 was stable, and 4.0.5 crashes, you'd think there's > something wrong between those two kernels and there were no changes to > mac80211 related to these code paths in there. Well 4.0.4 did hit it eventually, but it had been running stably for a month first. I then rebooted (because networking is basically wedged after this happens) and got 4.0.5 which hit it immediately as did several more reboots before I went back to the older kernel. Tom -- Tom Hughes (tom@xxxxxxxxxx) http://compton.nu/ -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html