Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH] generic_nvram: Turn nvram_ioctl into an unlocked ioctl | Date | Mon, 12 Oct 2009 00:25:05 +0200 |
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On Monday 12 October 2009, Frederic Weisbecker wrote: > nvram_ioctl is a bkl locked ioctl, but it can be an unlocked ioctl. > > - part is provided by the user > - offset is provided by pmac_get_partition() which is safe as it only > touches nvram_partitions, an array inistialized on __init time and > read-only the rest of the time. > - nvram_sync() only relies on core99_nvram_sync() which checks > is_core_99, nvram_data, nvram_image. Those are variables initialized > on __init time only and their direct values are not touched further. > The rest modifies the nvram image header, protected by nv_lock > already. > > So it's safe to call nvram_ioctl without the big kernel lock held. > > Reported-by: Arnd Bergmann <arndbergmann@googlemail.com> > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: John Kacur <jkacur@redhat.com> > Cc: Sven-Thorsten Dietrich <sven@thebigcorporation.com> > Cc: Jonathan Corbet <corbet@lwn.net> > Cc: Alessio Igor Bogani <abogani@texware.it> > Cc: Arnd Bergmann <arndbergmann@googlemail.com> > Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Hmm, I wish I had not started using the gmail MTA for sending out mail, not that address is public forever.
> drivers/char/generic_nvram.c | 10 +++++----- > 1 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/drivers/char/generic_nvram.c b/drivers/char/generic_nvram.c > index c49200e..fd448aa 100644 > --- a/drivers/char/generic_nvram.c > +++ b/drivers/char/generic_nvram.c > @@ -118,11 +118,11 @@ static int nvram_ioctl(struct inode *inode, struct file *file, > } > > const struct file_operations nvram_fops = { > - .owner = THIS_MODULE, > - .llseek = nvram_llseek, > - .read = read_nvram, > - .write = write_nvram, > - .ioctl = nvram_ioctl, > + .owner = THIS_MODULE, > + .llseek = nvram_llseek, > + .read = read_nvram, > + .write = write_nvram, > + .unlocked_ioctl = nvram_ioctl, > }; > > static struct miscdevice nvram_dev = {
The ioctl and unlocked_ioctl functions have a different signature, so you need to adapt that, not just rename it.
Not sure if we should do it in the same patch, but this driver should also have a compat_ioctl method pointing to the same function. The ioctl numbers in this driver are all 32/64 bit clean, but are not listed in fs/compat_ioctl.c, so adding a .compat_ioctl pointer is the easiest way to fix 32 bit userland accessing the device.
Arnd <><
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