Messages in this thread | | | Date | Wed, 14 Nov 2018 21:46:54 +0100 | From | Andrew Lunn <> | Subject | Re: [PATCH v2] net: phy: mdio-gpio: fix access that may sleep |
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On Wed, Nov 14, 2018 at 08:43:49AM +0100, Martin Schiller wrote: > On 2018-11-14 08:05, Andrew Lunn wrote: > >On Wed, Nov 14, 2018 at 07:37:03AM +0100, Martin Schiller wrote: > >>This commit re-enables support for slow GPIO pins. It was initially > >>introduced by commit > >> 2d6c9091ab7630dfcf34417c6683ce4764d7d40a > >>and got lost by commit > >> 7e5fbd1e0700f1bdb94508f84ec2aeb01eed7b12 > > > >Hi Martin > > > >Was it really lost? It looks like _cansleep() just adds an extra check > >might_sleep_if(extra_checks), but it does not change any > >functionality. > > Well, you are right, the functionality itself is not broken, but using > the NON _cansleep() functions on GPIOs that have the cansleep flag set, > this leads to a lot of kernel warnings/backtraces which makes the system > in fact useless. > > Thats the WARN_ON() here: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n2992 > > and here: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpio/gpiolib.c?h=v4.20-rc2#n3304
Hi Martin
Right, this is really what you are fixing. So the commit message should talk about these WARN_ON being hit.
> > > >So the change itself is O.K, i'm just not too sure about the commit > >message. > > > > Andrew > > Hmm, ok. What would you suggest for a better commit message?
Up until commit XXX, the _cansleep variants of the gpio_ API was used. After that commit and the change to gpiod_ API, the _cansleep() was dropped. This then results in WARN_ON() when used with GPIO devices which do sleep. Add back the _cansleep() to avoid this.
This is something which is useful in stable. So please base this fix on DaveM net tree, not net-next, and include a Fixes: tag for the patch which broke it.
Thanks Andrew
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