suspend mode
Hi all, I have a HWMON driver which is using simple pm options. So, I have a suspend() and resume() where I try to lock a mutex before suspending/resuming. This mutex is shared with the read/write path of the hwmon attributes. I also have a flag which is set when suspend() is done so that, if someone tries to read some attribute, will get an error since doing a read/write on the device bus will wake it up. Im starting to think that this does not make any sense. Is there any way that a userland process runs during suspend? As I understand, all tasks should be frozen before starting to suspend the HW devices. Is this right? Furthermore, now that I think about this, trying to lock the mutex on the PM callbacks seems dangerous since it can lead to deadlock (if some frozen task is helding the lock?). However, I definitely saw drivers trying to lock shared mutexes in the PM callbacks. Aren't these callbacks atomic? Is there any scenario where it makes to sense to care about concurrency in these functions? Thanks for the help! - Nuno Sá ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Contribute
On 22.07.2017 11:56, Greg KH wrote: > On Sat, Jul 22, 2017 at 11:39:45AM +0200, nunojsa wrote: >> Hi all, >> >> Im fairly new to linux kernel and would like to start with some staging work >> (seems like the best way to start). >> Basically what i would like to know is which tree should i clone for this? >> My understanding is that one should never work directly on top of the >> mainline tree, instead (for this case) on top of the linux staging tree. The >> same goes, for example, for USB subsystem development in which case i should >> just clone the usb development tree (and the same for all subsystems). >> >> Is my understanding correct? > > Yes it is, make sure you work off of the correct branch as well. For> the > staging tree, working off of the staging-next is best. This would be my next question. Regarding the linux-next tree, the same as i wrote before also applies? So, I should not work directly in the linux-next tree but instead in the correspondent branch (subsystem-next) of the specific subsystem I'm working on? > > thanks and good luck! > > greg k-h > Thanks for your help! ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Contribute
Hi all, Im fairly new to linux kernel and would like to start with some staging work (seems like the best way to start). Basically what i would like to know is which tree should i clone for this? My understanding is that one should never work directly on top of the mainline tree, instead (for this case) on top of the linux staging tree. The same goes, for example, for USB subsystem development in which case i should just clone the usb development tree (and the same for all subsystems). Is my understanding correct? Thank you in advance! ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
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