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Subject[GIT PULL v2] Preparation for BKL'ed ioctl removal
Date
Linus,

In this v2, I've removed the declaration of default_llseek
from smp_lock.h, as this export can be made later (we
want to make any use of default_llseek() depend on
CONFIG_BKL as well, but that can wait).

Please pull the bkl/ioctl-v2 branch that can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
bkl/ioctl-v2

Thanks,
Frederic
---

Arnd Bergmann (1):
vfs: Introduce CONFIG_BKL and deprecated_ioctl


fs/ioctl.c | 22 ++++++++++++++++++++++
include/linux/fs.h | 3 +++
include/linux/smp_lock.h | 3 +++
kernel/Kconfig.locks | 10 ++++++++++
4 files changed, 38 insertions(+), 0 deletions(-)

---
commit 333f5fb46d15d057f0d69da0dd8b0a3db89bf34f
Author: Arnd Bergmann <arnd@arndb.de>
Date: Thu Apr 1 14:42:38 2010 +0200

vfs: Introduce CONFIG_BKL and deprecated_ioctl

This is a preparation for the removal of the big kernel lock that
introduces new interfaces for device drivers still using it.

We can start marking those device drivers as 'depends on CONFIG_BKL'
now, and make that symbol optional later, when the point has come
at which we are able to build a kernel without the BKL.

Similarly, device drivers that currently make use of the implicit
BKL locking around the ioctl function can now get annotated by
changing

.ioctl = foo_ioctl,

to

.locked_ioctl = foo_ioctl,
.unlocked_ioctl = deprecated_ioctl,

As soon as no driver remains using the old ioctl callback, it can
get removed.

[fweisbec: move config bkl from Kconfig.debug to Kconfig.locks,
rename default_ioctl to deprecated_ioctl]

v2: Remove default_llseek() declaration from smp_lock.h, we
don't need to prepare it to be modularized right now.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --git a/fs/ioctl.c b/fs/ioctl.c
index 6c75110..e6d6a75 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -58,6 +58,28 @@ static long vfs_ioctl(struct file *filp, unsigned int cmd,
return error;
}

+#ifdef CONFIG_BKL
+/*
+ * deprecated_ioctl - call locked_ioctl with BKL held
+ *
+ * Setting only the ioctl operation but not unlocked_ioctl will become
+ * invalid in the future, all drivers that are not converted to unlocked_ioctl
+ * should set .unlocked_ioctl = deprecated_ioctl now.
+ */
+long deprecated_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
+{
+ int error = -ENOTTY;
+ if (filp->f_op->locked_ioctl) {
+ lock_kernel();
+ error = filp->f_op->locked_ioctl(filp->f_path.dentry->d_inode,
+ filp, cmd, arg);
+ unlock_kernel();
+ }
+ return error;
+}
+EXPORT_SYMBOL_GPL(default_ioctl);
+#endif
+
static int ioctl_fibmap(struct file *filp, int __user *p)
{
struct address_space *mapping = filp->f_mapping;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 39d57bc..6b65b26 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1492,6 +1492,9 @@ struct file_operations {
int (*readdir) (struct file *, void *, filldir_t);
unsigned int (*poll) (struct file *, struct poll_table_struct *);
int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
+#ifdef CONFIG_BKL
+ int (*locked_ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
+#endif
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
diff --git a/include/linux/smp_lock.h b/include/linux/smp_lock.h
index 2ea1dd1..3ed34da 100644
--- a/include/linux/smp_lock.h
+++ b/include/linux/smp_lock.h
@@ -62,4 +62,7 @@ static inline void cycle_kernel_lock(void)
#define kernel_locked() 1

#endif /* CONFIG_LOCK_KERNEL */
+
+long deprecated_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
+
#endif /* __LINUX_SMPLOCK_H */
diff --git a/kernel/Kconfig.locks b/kernel/Kconfig.locks
index 88c92fb..9a80413 100644
--- a/kernel/Kconfig.locks
+++ b/kernel/Kconfig.locks
@@ -200,3 +200,13 @@ config INLINE_WRITE_UNLOCK_IRQRESTORE

config MUTEX_SPIN_ON_OWNER
def_bool SMP && !DEBUG_MUTEXES && !HAVE_DEFAULT_NO_SPIN_MUTEXES
+
+config BKL
+ def_bool y
+ help
+ This is the traditional lock that is used in old code instead
+ of proper locking. All drivers that use the BKL should depend
+ on this symbol.
+ This configuration option will become user-selectable in the
+ future, as soon as it is possible to build a kernel without
+ it.

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