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. Signed-off-by: Frederic Weisbecker Cc: John Kacur Cc: Sven-Thorsten Dietrich Cc: Jonathan Corbet Cc: Alessio Igor Bogani Cc: Greg Kroah-Hartman LKML-Reference: <1255113062-5835-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Thomas Gleixner --- drivers/char/mem.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) Index: linux-2.6-tip/drivers/char/mem.c =================================================================== --- linux-2.6-tip.orig/drivers/char/mem.c +++ linux-2.6-tip/drivers/char/mem.c @@ -26,7 +26,6 @@ #include #include #include -#include #include #include @@ -892,29 +891,23 @@ static int memory_open(struct inode *ino { 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 = { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/