Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759923AbYG2Oqd (ORCPT ); Tue, 29 Jul 2008 10:46:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758801AbYG2OqJ (ORCPT ); Tue, 29 Jul 2008 10:46:09 -0400 Received: from mail.windriver.com ([147.11.1.11]:60961 "EHLO mail.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758655AbYG2OqG (ORCPT ); Tue, 29 Jul 2008 10:46:06 -0400 From: Mark Asselstine To: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [PATCH] Removal of the deprecated cli() sti() functions. Date: Tue, 29 Jul 2008 10:46:03 -0400 Message-Id: <1217342763-19568-1-git-send-email-mark.asselstine@windriver.com> X-Mailer: git-send-email 1.5.5.1 X-OriginalArrivalTime: 29 Jul 2008 14:46:05.0007 (UTC) FILETIME=[D40685F0:01C8F189] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6734 Lines: 213 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 --- 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 - - -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 -- 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/