[PATCH] Removal of the deprecated cli() sti() functions.

[PATCH] Removal of the deprecated cli() sti() functions.

[Mark Asselstine]

These functions have been deprecated for some time now
but remained until all legacy callers could be removed.
With a few commits in 2.6.26 this has happened so now
we can remove these deprecated functions.

Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
---
 Documentation/00-INDEX            |    2 -
 Documentation/cli-sti-removal.txt |  133 -------------------------------------
 include/linux/interrupt.h         |   29 --------
 3 files changed, 0 insertions(+), 164 deletions(-)
 delete mode 100644 Documentation/cli-sti-removal.txt

diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index 6de7130..5b5aba4 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -89,8 +89,6 @@ cciss.txt
 	- info, major/minor #'s for Compaq's SMART Array Controllers.
 cdrom/
 	- directory with information on the CD-ROM drivers that Linux has.
-cli-sti-removal.txt
-	- cli()/sti() removal guide.
 computone.txt
 	- info on Computone Intelliport II/Plus Multiport Serial Driver.
 connector/
diff --git a/Documentation/cli-sti-removal.txt b/Documentation/cli-sti-removal.txt
deleted file mode 100644
index 60932b0..0000000
--- a/Documentation/cli-sti-removal.txt
+++ /dev/null
@@ -1,133 +0,0 @@
-
-#### cli()/sti() removal guide, started by Ingo Molnar <mingo@redhat.com>
-
-
-as of 2.5.28, five popular macros have been removed on SMP, and
-are being phased out on UP:
-
- cli(), sti(), save_flags(flags), save_flags_cli(flags), restore_flags(flags)
-
-until now it was possible to protect driver code against interrupt
-handlers via a cli(), but from now on other, more lightweight methods
-have to be used for synchronization, such as spinlocks or semaphores.
-
-for example, driver code that used to do something like:
-
-	struct driver_data;
-
-	irq_handler (...)
-	{
-		....
-		driver_data.finish = 1;
-		driver_data.new_work = 0;
-		....
-	}
-
-	...
-
-	ioctl_func (...)
-	{
-		...
-		cli();
-		...
-		driver_data.finish = 0;
-		driver_data.new_work = 2;
-		...
-		sti();
-		...
-	}
-
-was SMP-correct because the cli() function ensured that no
-interrupt handler (amongst them the above irq_handler()) function
-would execute while the cli()-ed section is executing.
-
-but from now on a more direct method of locking has to be used:
-
-	DEFINE_SPINLOCK(driver_lock);
-	struct driver_data;
-
-	irq_handler (...)
-	{
-		unsigned long flags;
-		....
-		spin_lock_irqsave(&driver_lock, flags);
-		....
-		driver_data.finish = 1;
-		driver_data.new_work = 0;
-		....
-		spin_unlock_irqrestore(&driver_lock, flags);
-		....
-	}
-
-	...
-
-	ioctl_func (...)
-	{
-		...
-		spin_lock_irq(&driver_lock);
-		...
-		driver_data.finish = 0;
-		driver_data.new_work = 2;
-		...
-		spin_unlock_irq(&driver_lock);
-		...
-	}
-
-the above code has a number of advantages:
-
-- the locking relation is easier to understand - actual lock usage
-  pinpoints the critical sections. cli() usage is too opaque.
-  Easier to understand means it's easier to debug.
-
-- it's faster, because spinlocks are faster to acquire than the
-  potentially heavily-used IRQ lock. Furthermore, your driver does
-  not have to wait eg. for a big heavy SCSI interrupt to finish,
-  because the driver_lock spinlock is only used by your driver.
-  cli() on the other hand was used by many drivers, and extended
-  the critical section to the whole IRQ handler function - creating
-  serious lock contention.
-
- 
-to make the transition easier, we've still kept the cli(), sti(),
-save_flags(), save_flags_cli() and restore_flags() macros defined
-on UP systems - but their usage will be phased out until 2.6 is
-released.
-
-drivers that want to disable local interrupts (interrupts on the
-current CPU), can use the following five macros:
-
-  local_irq_disable(), local_irq_enable(), local_save_flags(flags),
-  local_irq_save(flags), local_irq_restore(flags)
-
-but beware, their meaning and semantics are much simpler, far from
-that of the old cli(), sti(), save_flags(flags) and restore_flags(flags)
-SMP meaning:
-
-    local_irq_disable()       => turn local IRQs off
-
-    local_irq_enable()        => turn local IRQs on
-
-    local_save_flags(flags)   => save the current IRQ state into flags. The
-                                 state can be on or off. (on some
-                                 architectures there's even more bits in it.)
-
-    local_irq_save(flags)     => save the current IRQ state into flags and
-                                 disable interrupts.
-
-    local_irq_restore(flags)  => restore the IRQ state from flags.
-
-(local_irq_save can save both irqs on and irqs off state, and
-local_irq_restore can restore into both irqs on and irqs off state.)
-
-another related change is that synchronize_irq() now takes a parameter:
-synchronize_irq(irq). This change too has the purpose of making SMP
-synchronization more lightweight - this way you can wait for your own
-interrupt handler to finish, no need to wait for other IRQ sources.
-
-
-why were these changes done? The main reason was the architectural burden
-of maintaining the cli()/sti() interface - it became a real problem. The
-new interrupt system is much more streamlined, easier to understand, debug,
-and it's also a bit faster - the same happened to it that will happen to
-cli()/sti() using drivers once they convert to spinlocks :-)
-
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 62aa4f8..58ff4e7 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -223,35 +223,6 @@ static inline int disable_irq_wake(unsigned int irq)
 #define or_softirq_pending(x)  (local_softirq_pending() |= (x))
 #endif
 
-/*
- * Temporary defines for UP kernels, until all code gets fixed.
- */
-#ifndef CONFIG_SMP
-static inline void __deprecated cli(void)
-{
-	local_irq_disable();
-}
-static inline void __deprecated sti(void)
-{
-	local_irq_enable();
-}
-static inline void __deprecated save_flags(unsigned long *x)
-{
-	local_save_flags(*x);
-}
-#define save_flags(x) save_flags(&x)
-static inline void __deprecated restore_flags(unsigned long x)
-{
-	local_irq_restore(x);
-}
-
-static inline void __deprecated save_and_cli(unsigned long *x)
-{
-	local_irq_save(*x);
-}
-#define save_and_cli(x)	save_and_cli(&x)
-#endif /* CONFIG_SMP */
-
 /* Some architectures might implement lazy enabling/disabling of
  * interrupts. In some cases, such as stop_machine, we might want
  * to ensure that after a local_irq_disable(), interrupts have
-- 
1.5.5.1

Re: [PATCH] Removal of the deprecated cli() sti() functions.

[Matthew Wilcox]

On Tue, Jul 29, 2008 at 10:46:03AM -0400, Mark Asselstine wrote:
> These functions have been deprecated for some time now
> but remained until all legacy callers could be removed.
> With a few commits in 2.6.26 this has happened so now
> we can remove these deprecated functions.
> 
> Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>

Yay!

Reviewed-by: Matthew Wilcox <willy@linux.intel.com>

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."