Messages in this thread | | | Date | Fri, 9 Oct 2009 20:34:32 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH] mem_class: Drop the bkl from memory_open() |
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On Fri, 9 Oct 2009, Frederic Weisbecker wrote:
> The generic open callback for the mem class devices is "protected" by > the bkl. > > Let's look at the datas manipulated inside memory_open: > > - inode and file: safe > - the devlist: safe because it is constant > - the memdev classes inside this array are safe too (constant) > > After we find out which memdev file operation we need to use, we call > its open callback. Depending on the targeted memdev, we call either > open_port() that doesn't manipulate any racy data (just a capable() > check), or we call nothing. > > So it's safe to remove the big kernel lock there.
Thanks, queued.
tglx
> 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> > --- > drivers/char/mem.c | 16 +++++----------- > 1 files changed, 5 insertions(+), 11 deletions(-) > > diff --git a/drivers/char/mem.c b/drivers/char/mem.c > index a074fce..599846a 100644 > --- a/drivers/char/mem.c > +++ b/drivers/char/mem.c > @@ -892,29 +892,23 @@ static int memory_open(struct inode *inode, struct file *filp) > { > int minor; > const struct memdev *dev; > - int ret = -ENXIO; > - > - lock_kernel(); > > minor = iminor(inode); > if (minor >= ARRAY_SIZE(devlist)) > - goto out; > + return -ENXIO; > > dev = &devlist[minor]; > if (!dev->fops) > - goto out; > + return -ENXIO; > > filp->f_op = dev->fops; > if (dev->dev_info) > filp->f_mapping->backing_dev_info = dev->dev_info; > > if (dev->fops->open) > - ret = dev->fops->open(inode, filp); > - else > - ret = 0; > -out: > - unlock_kernel(); > - return ret; > + return dev->fops->open(inode, filp); > + > + return 0; > } > > static const struct file_operations memory_fops = { > -- > 1.6.2.3 >
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