Greg KH <greg@xxxxxxxxx> writes: > On Mon, Nov 30, 2009 at 01:33:37PM -0800, Greg KH wrote: >> On Sat, Nov 07, 2009 at 11:25:03PM -0800, Eric W. Biederman wrote: >> > >> > The sysfs code updates the vfs caches immediately when the sysfs data >> > structures change causing a lot of unnecessary complications. The >> > following patchset untangles that beast. Allowing for simpler >> > more straight forward code, the removal of a hack from the vfs >> > to support sysfs, and human comprehensible locking on sysfs. >> > >> > Most of these patches have already been reviewed and acked from the >> > last time I had time to work on sysfs. >> > >> > This acks have been folded in and the two small bugs found in the >> > previous review have been fixed in the trailing patches (they are >> > minor enough nits that even a bisect that happens to land in the >> > middle should not see sysfs problems). >> >> I've applied all of these to my tree now, and sorry, but something is >> broken pretty badly. >> >> When doing a simple 'ls /sys/class/input/' the process locks up. This >> means that X can't find any input devices, which makes for a bit of a >> problem when wanting to use your mouse or keyboard :( >> >> Attached is the state of my processes when this happens, if that helps >> out any. >> >> So I'm going to drop all of these from my tree again, as they are not >> ready for merging at this point :( > > In looking at the stuck processes, it seems your last patch was the > problem. Removing that caused things to work again, so I've only > dropped that one. > > Next time, please test your patches before submitting them :( Weird I thought I had tested this. That last patch to add locking that is only needed for vfs coherency has certainly seen less testing than the others. I also remember verify that nfs does the same thing, when in fact nfs takes inode->i_lock not inode->i_mutex in the same situation. generic_permission takes no locks so this is really about serializing writes to the inode. The vfs only takes inode->i_mutex, when calling notify_change. So it appears I have stepped into a murky corner of the vfs. I will take a look and do a bit more testing. At the moment it looks like a solution to serializing writes to the stat attributes on the inode is going to be simply holding sysfs_mutex over inode_setattr in sysfs_setattr. Assuming a solution is needed at all. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
