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    SubjectRe: [PATCH 7/8] soundcore_open: Reduce the area BKL coverage
    At Sun,  4 Jul 2010 00:02:31 +0200,
    Arnd Bergmann wrote:
    >
    > From: John Kacur <jkacur@redhat.com>
    >
    > Most of this function is protected by the sound_loader_lock.
    > We can push down the BKL to this call out err = file->f_op->open(inode,file);
    >
    > In order to build the sound core without the BKL, we
    > will need to push the lock_kernel() call into the ~20
    > device drivers that register their file operations.
    >
    > Signed-off-by: John Kacur <jkacur@redhat.com>
    > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    > Acked-by: Alan Cox <alan@linux.intel.com>
    > Cc: Takashi Iwai <tiwai@suse.de>

    I applied this one to sound git tree now. Thanks!


    Takashi

    > ---
    > sound/sound_core.c | 13 ++++++++-----
    > 1 files changed, 8 insertions(+), 5 deletions(-)
    >
    > diff --git a/sound/sound_core.c b/sound/sound_core.c
    > index 7c2d677..c8627fc 100644
    > --- a/sound/sound_core.c
    > +++ b/sound/sound_core.c
    > @@ -576,8 +576,6 @@ static int soundcore_open(struct inode *inode, struct file *file)
    > struct sound_unit *s;
    > const struct file_operations *new_fops = NULL;
    >
    > - lock_kernel ();
    > -
    > chain=unit&0x0F;
    > if(chain==4 || chain==5) /* dsp/audio/dsp16 */
    > {
    > @@ -630,18 +628,23 @@ static int soundcore_open(struct inode *inode, struct file *file)
    > const struct file_operations *old_fops = file->f_op;
    > file->f_op = new_fops;
    > spin_unlock(&sound_loader_lock);
    > - if(file->f_op->open)
    > +
    > + if (file->f_op->open) {
    > + /* TODO: push down BKL into indivial open functions */
    > + lock_kernel();
    > err = file->f_op->open(inode,file);
    > + unlock_kernel();
    > + }
    > +
    > if (err) {
    > fops_put(file->f_op);
    > file->f_op = fops_get(old_fops);
    > }
    > +
    > fops_put(old_fops);
    > - unlock_kernel();
    > return err;
    > }
    > spin_unlock(&sound_loader_lock);
    > - unlock_kernel();
    > return -ENODEV;
    > }
    >
    > --
    > 1.7.1
    >


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