On Jan 18, 2008 7:26 AM, Jarek Poplawski <[EMAIL PROTECTED]> wrote: > > On Thu, Jan 17, 2008 at 09:31:55PM +0100, Jarek Poplawski wrote: > > On Thu, Jan 17, 2008 at 02:57:36PM -0500, Alan Stern wrote: > > > On Thu, 17 Jan 2008, Jarek Poplawski wrote: > > > > > > > On Thu, Jan 17, 2008 at 10:16:30AM -0500, Alan Stern wrote: > > > > > On Thu, 17 Jan 2008, Dave Young wrote: > > > > > > > > > > > > Your meaning isn't clear. Do you mean that your patch doesn't > > > > > > > generate > > > > > > > any lockdep warnings at all? Or do you mean that it generates a > > > > > > > single > > > > > > > lockdep warning at boot time and then no more warnings afterward? > > > > > > > > > > > > I means the latter one. > > > > > > > > > > That's very bad. > > > > > > > > > > For each type of violation, lockdep only gives one error message. So > > > > > the fact that you get one message at boot time and then no more > > > > > doesn't > > > > > mean the code is almost right -- it probably means the code has lots > > > > > of > > > > > errors and you're seeing only the first one. > > > > > > > > I hope it's better than this: lockdep really stops checking after first > > > > warning, but I've understood from David's description that after fixing > > > > this one place lockdep seems to be pleased. > > > > > > That isn't what Dave said above; he said that lockdep produces a single > > > warning at bootup. If he did mention anything about one place being > > > fixed up or lockdep being pleased, it was a while back and I've lost > > > track of it. > > > > > > If I recall correctly the nature of the warning was that a method > > > routine for one class (called with the class's mutex held) was creating > > > a second class and locking that class's mutex. In principle this is > > > perfectly legal and should be allowed for arbitrary depths of nesting, > > > even though it is the sort of thing lockdep is currently unable to > > > handle. > > > > You are definitely right! After first reading Dave's description I got > > it the same way, but after re-reading I probably was misled with this > > "thus"! Only now I've had a look at this warning and there is really > > mutex_lock_nested(). Sorry Alan! > > But, on the other hand, mutex_lock() is really mutex_lock_nested(), and > after second checking this lockdep warning from Jan. 3, it seems > impossible it was get after this patch... > > Dave, could you please answer with full sentence if there is any lockdep > warning possible after applying these 1-7/7 patches, and if so, attach > current warning? Otherwise, I'll have apologized for this everybody from > the list soon!
After digging the class usage code again, I found that the only possible double lock place is the class_interface_register/unregister in which the class_device api could be called. The scsi and pcmcia use the class_interface api, I just found the warning above caused by scsi part then. So I think I will need to use mutex_lock_nesting for the class_device_* functions. Thank you a lot. > > Jarek P. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
