On Tue, Jul 25, 2017 at 11:56:01PM +0100, Ben Hutchings wrote: > On Wed, 2017-07-19 at 13:12 +0200, Greg Kroah-Hartman wrote: > > 4.4-stable review patch. If anyone has any objections, please let me know. > > > > ------------------ > > > > From: Jason Gunthorpe <[email protected]> > > > > commit 4e26195f240d73150e8308ae42874702e3df8d2c upstream. > > > > Add a read/write semaphore around the ops function pointers so > > ops can be set to null when the driver un-registers. > [...] > > @@ -49,10 +99,10 @@ struct tpm_chip *tpm_chip_find_get(int c > > if (chip_num != TPM_ANY_NUM && chip_num != pos->dev_num) > > continue; > > > > - if (try_module_get(pos->dev.parent->driver->owner)) { > > + /* rcu prevents chip from being free'd */ > > + if (!tpm_try_get_ops(pos)) > [...] > > But an RCU read-side critical section is an atomic context, and > semaphore operations can block! Fixed upstream by: > > commit 15516788e581eb32ec1c50e5f00aba3faf95d817 > Author: Stefan Berger <[email protected]> > Date: Mon Feb 29 08:53:02 2016 -0500 > > tpm: Replace device number bitmap with IDR
Ugh, that's a big patch. Jason, Stefan, and Jarkko, what do you think? Should I also take this for 4.4-stable? thanks, greg k-h
