Date: Sun, 08 Jul 2007 22:18:31 -0600 From: Scott Long <scottl@samsco.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: Tai-hwa Liang <avatar@mmlab.cse.yzu.edu.tw>, current@freebsd.org Subject: Re: HEADS UP: destroy_dev_sched() KPI in the tree Message-ID: <4691B717.502@samsco.org> In-Reply-To: <20070708191928.GM2200@deviant.kiev.zoral.com.ua> References: <20070703180141.GJ2200@deviant.kiev.zoral.com.ua> <E1I6SAN-0000by-Bt@cs1.cs.huji.ac.il> <20070705144443.GV2200@deviant.kiev.zoral.com.ua> <c21e92e20707070536x6c8053c0l7ecad5a5bfa6de15@mail.gmail.com> <20070707160042.GJ2200@deviant.kiev.zoral.com.ua> <07070809441413.59322@www.mmlab.cse.yzu.edu.tw> <20070708024815.GK2200@deviant.kiev.zoral.com.ua> <0707082155317.77206@www.mmlab.cse.yzu.edu.tw> <20070708191928.GM2200@deviant.kiev.zoral.com.ua>
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Kostik Belousov wrote: > On Sun, Jul 08, 2007 at 10:00:14PM +0800, Tai-hwa Liang wrote: > >>On Sun, 8 Jul 2007, Kostik Belousov wrote: >> >>>On Sun, Jul 08, 2007 at 09:47:41AM +0800, Tai-hwa Liang wrote: >> >>[...] >> >>>> Though it was reviewed before destroy_dev_sched() KPI enters to the >>>> tree, >>>>I'd be appreciate it if you can reviewed the attached patch again. >>> >>>So, this is still the problem for scsi_targ ? >>> >>>It probably make sense to postpone free of softc until all threads >>>finished using it. You may use destroy_dev_sched_cb() to run the >>>function after the device is actually destroyed. It would just call >>>free(). >> >> Probably; however, I did not see any code inside scsi_target.c to >>detach or unregister the scsi_target device. Will this cause any >>cdev leakage? > > This is not about cdev linkage. Immediately after call to > destriy_dev_sched(), driver code frees dev' softc. Thus, if any thread > is still inside cdev method, it could access freed memory. Postponing > the call to free until all threads leave the cdev methods would eliminate > this bug. > Nate and I and the other SCSI guys can take a whack at scsi_targ, so don't worry too much about slaying the dragons in it. Scott
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