From: Igor Mammedov Date: Tue, 14 May 2013 14:46:07 +0000 (+0200) Subject: cpu: make sure that cpu/online file created before KOBJ_ADD is emitted X-Git-Tag: omap-for-v3.11/fixes-for-merge-window~74^2~26 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1c4e2d70afb132058bfe979f6854c1d0a732b556;p=pandora-kernel.git cpu: make sure that cpu/online file created before KOBJ_ADD is emitted It fixes race between udev and hotplugged CPU registration by defining "online" attribute statically, so that device_add() would create it before notifying udev about new CPU. Original issue report is at https://lkml.org/lkml/2012/4/30/198 " > On Mon, Apr 30, 2012 at 11:36:23AM -0400, Konrad Rzeszutek Wilk wrote: > > Hey Greg, > > > > Hoping you can help with some guidance on how to fix this. > > > > The issue is with CPU hotplug is that when a CPU goes up > > it calls 'arch_register_cpu' which eventually calls > > register_cpu. That function does these two things: > > > > 251 error = device_register(&cpu->dev); > > 252 if (!error && cpu->hotpluggable) > > 253 register_cpu_control(cpu); > > > > and the device_register creates a nice little SysFS directory: > > > > /sys/devices/system/cpu/cpu2/ which at line 251 has the 'add' attribute > > but no 'online' attribute. udev then tries to echo 1 to the 'online' > > and it we get: > > udevd-work[2421]: error opening ATTR{/sys/devices/system/cpu/cpu2/online} for writing: No such file or directory > > > > Line 253 creates said 'online' and at that time udev [or the system admin] > > can write 1 to 'online' and the CPU goes up. > > > > So .. any thoughts? Is there some way to inhibit from uevent being sent > > until line 253 has run? " Signed-off-by: Igor Mammedov Tested-by: Konrad Rzeszutek Wilk Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed