Hi, On Sun, Sep 13, 2009 at 3:53 PM, Mark Ryden <[email protected]> wrote: > Hello, > > I have a question about spinlocks and copy_to_user(): > copy_to_user() can sleep > so it should not be called when a spin_lock is held. > > However, I have data (a structure, not atomic variable) which can be > changed in interrupt context > in my module; so this data is protected by spinlocks. > > I use ioctl to pass this data to user space; this ioctl() calls > copy_to_user(); when I call spin_lock_bh() > before cp[y_to_user() in this ioctl , I get: > Use a local variable in ioctl: In the critical section copy your data into this variable using memcpy. Outside the critical section call copy_to_user.
> "kernel: BUG: sleeping function called from invalid > context at include/linux/kernel.h:155". > > How should I call copy_to_user() so that it won't pass wrong data to > user space ? If I remove the > spin_lock_bh() before the call to copy_to_user() , I have a chance to > copy wrong data (to copy data while it is changing in my module ). > > Regards, > Mark > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to [email protected] > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
