Messages in this thread | | | Subject | Re: [PATCH 4.4 16/30] [media] pvrusb2: reduce stack usage pvr2_eeprom_analyze() | From | Ben Hutchings <> | Date | Mon, 03 Jul 2017 14:37:46 +0100 |
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On Mon, 2017-07-03 at 09:47 +0200, Arnd Bergmann wrote: > On Mon, Jul 3, 2017 at 9:31 AM, Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > On Thu, Jun 29, 2017 at 05:15:17PM +0100, Ben Hutchings wrote: > >> On Mon, 2017-06-19 at 23:20 +0800, Greg Kroah-Hartman wrote: > >> > 4.4-stable review patch. If anyone has any objections, please let me know. > >> > > >> > From: Arnd Bergmann <arnd@arndb.de> > >> > > >> > commit 6830733d53a4517588e56227b9c8538633f0c496 upstream. [...] > >> > Further analysis shows that putting an 'i2c_client' structure on > >> > the stack is not really supported, as the embedded 'struct device' > >> > is not initialized here, and we are only saved by the fact that > >> > the function that is called here does not use the pointer at all. > >> [...] > >> > >> That is not true in 4.4-stable. This commit depends on: > >> > >> commit 6037b3ca28f4258d913dbe77248fd77827702ae3 > >> Author: Mauro Carvalho Chehab <mchehab@s-opensource.com> > >> Date: Wed Nov 16 14:21:48 2016 -0200 > >> > >> [media] tveeprom: print log messages using pr_foo() > > > > It does? I don't understand how the two are connected. Removing > > i2c_client off of the stack is a good thing. Ah, I see how the pointer > > is used in tveeprom_hauppauge_analog(), but this shouldn't matter here, > > right? > > My reading of the two patches is that we actually need at least one > of them to avoid interpreting uninitialized dev->class/bus: With just my > 6830733d53a patch, we replace the uninitialized data with a NULL > pointer, which is handled gracefully in __dev_printk(), while the > 6037b3ca28 patch by itself will avoid using the 'dev' pointer completely, > and give a saner output (no "(NULL device)" string or worse). > > I think we probably want both of them backported to 4.4, but I don't see a > dependency between them.
Sorry, I mixed up two commits. The one actually needed to avoid a null dereference is:
commit 7cda4c5bae46ffca3abeadc4c1882d9325ee3102 Author: Mauro Carvalho Chehab <mchehab@s-opensource.com> Date: Thu Oct 13 10:51:20 2016 -0300
[media] tveeprom: use dev_foo() for printk messages
Then "[media] tveeprom: print log messages using pr_foo()" is cleanup on top of that.
Ben.
-- Ben Hutchings Software Developer, Codethink Ltd.
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