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    Subject[PATCH] spinlock.h cleanup
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    Linus,

    Ingo's IRQ rewrite cleaned up include/linux/spinlock.h a bit but it
    still resembles a dying albatross. Some of the defines are redundant,
    the coding style used by the remaining defines is likely drug induced,
    and there are a couple other issues...

    - cleanup #defines: I do not follow the rationale behind the odd
    line-wrapped defines at the beginning of the file. If we have to
    use multiple lines, then we might as well do so cleanly and
    according to normal practice...

    - we do not need to define the spin_lock functions twice, once
    for CONFIG_PREEMPT and once for !CONFIG_PREEMPT. Defining
    them once with the preempt macros will optimize away fine.

    - remove the egcs compiler workarounds: we do not need them

    - other misc. minor cleanup, improved comments, et cetera

    Tested on UP, SMP, and preempt. Object code is unchanged. Patch is
    against 2.5-bk but should apply to 2.5.29. Please, apply.

    Robert Love

    diff -urN linux-2.5.29-bk/include/linux/preempt.h linux/include/linux/preempt.h
    --- linux-2.5.29-bk/include/linux/preempt.h Mon Jul 29 15:59:01 2002
    +++ linux/include/linux/preempt.h Mon Jul 29 16:34:12 2002
    @@ -1,6 +1,11 @@
    #ifndef __LINUX_PREEMPT_H
    #define __LINUX_PREEMPT_H

    +/*
    + * include/linux/preempt.h - macros for accessing and manipulating
    + * preempt_count (used for kernel preemption, interrupt count, etc.)
    + */
    +
    #include <linux/config.h>

    #define preempt_count() (current_thread_info()->preempt_count)
    @@ -37,7 +42,7 @@
    #else

    #define preempt_disable() do { } while (0)
    -#define preempt_enable_no_resched() do {} while(0)
    +#define preempt_enable_no_resched() do { } while (0)
    #define preempt_enable() do { } while (0)
    #define preempt_check_resched() do { } while (0)

    diff -urN linux-2.5.29-bk/include/linux/spinlock.h linux/include/linux/spinlock.h
    --- linux-2.5.29-bk/include/linux/spinlock.h Mon Jul 29 15:59:01 2002
    +++ linux/include/linux/spinlock.h Mon Jul 29 16:34:33 2002
    @@ -11,39 +11,80 @@
    #include <asm/system.h>

    /*
    - * These are the generic versions of the spinlocks and read-write
    - * locks..
    + * These are the generic versions of the spinlocks and read-write locks..
    */
    -#define spin_lock_irqsave(lock, flags) do { local_irq_save(flags); spin_lock(lock); } while (0)
    -#define spin_lock_irq(lock) do { local_irq_disable(); spin_lock(lock); } while (0)
    -#define spin_lock_bh(lock) do { local_bh_disable(); spin_lock(lock); } while (0)
    -
    -#define read_lock_irqsave(lock, flags) do { local_irq_save(flags); read_lock(lock); } while (0)
    -#define read_lock_irq(lock) do { local_irq_disable(); read_lock(lock); } while (0)
    -#define read_lock_bh(lock) do { local_bh_disable(); read_lock(lock); } while (0)
    -
    -#define write_lock_irqsave(lock, flags) do { local_irq_save(flags); write_lock(lock); } while (0)
    -#define write_lock_irq(lock) do { local_irq_disable(); write_lock(lock); } while (0)
    -#define write_lock_bh(lock) do { local_bh_disable(); write_lock(lock); } while (0)
    -
    -#define spin_unlock_irqrestore(lock, flags) do { _raw_spin_unlock(lock); local_irq_restore(flags); preempt_enable(); } while (0)
    -#define _raw_spin_unlock_irqrestore(lock, flags) do { _raw_spin_unlock(lock); local_irq_restore(flags); } while (0)
    -#define spin_unlock_irq(lock) do { _raw_spin_unlock(lock); local_irq_enable(); preempt_enable(); } while (0)
    -#define spin_unlock_bh(lock) do { spin_unlock(lock); local_bh_enable(); } while (0)
    -
    -#define read_unlock_irqrestore(lock, flags) do { _raw_read_unlock(lock); local_irq_restore(flags); preempt_enable(); } while (0)
    -#define read_unlock_irq(lock) do { _raw_read_unlock(lock); local_irq_enable(); preempt_enable(); } while (0)
    -#define read_unlock_bh(lock) do { read_unlock(lock); local_bh_enable(); } while (0)
    -
    -#define write_unlock_irqrestore(lock, flags) do { _raw_write_unlock(lock); local_irq_restore(flags); preempt_enable(); } while (0)
    -#define write_unlock_irq(lock) do { _raw_write_unlock(lock); local_irq_enable(); preempt_enable(); } while (0)
    -#define write_unlock_bh(lock) do { write_unlock(lock); local_bh_enable(); } while (0)
    -#define spin_trylock_bh(lock) ({ int __r; local_bh_disable();\
    - __r = spin_trylock(lock); \
    - if (!__r) local_bh_enable(); \
    - __r; })
    +#define spin_lock_irqsave(lock, flags) \
    + do { local_irq_save(flags); spin_lock(lock); } while (0)

    -/* Must define these before including other files, inline functions need them */
    +#define spin_lock_irq(lock) \
    + do { local_irq_disable(); spin_lock(lock); } while (0)
    +
    +#define spin_lock_bh(lock) \
    + do { local_bh_disable(); spin_lock(lock); } while (0)
    +
    +#define read_lock_irqsave(lock, flags) \
    + do { local_irq_save(flags); read_lock(lock); } while (0)
    +
    +#define read_lock_irq(lock) \
    + do { local_irq_disable(); read_lock(lock); } while (0)
    +
    +#define read_lock_bh(lock) \
    + do { local_bh_disable(); read_lock(lock); } while (0)
    +
    +#define write_lock_irqsave(lock, flags) \
    + do { local_irq_save(flags); write_lock(lock); } while (0)
    +
    +#define write_lock_irq(lock) \
    + do { local_irq_disable(); write_lock(lock); } while (0)
    +
    +#define write_lock_bh(lock) \
    + do { local_bh_disable(); write_lock(lock); } while (0)
    +
    +#define spin_unlock_irqrestore(lock, flags) do { \
    + _raw_spin_unlock(lock); local_irq_restore(flags); preempt_enable(); \
    +} while (0)
    +
    +#define _raw_spin_unlock_irqrestore(lock, flags) \
    + do { _raw_spin_unlock(lock); local_irq_restore(flags); } while (0)
    +
    +#define spin_unlock_irq(lock) do { \
    + _raw_spin_unlock(lock); local_irq_enable(); preempt_enable(); \
    +} while (0)
    +
    +#define spin_unlock_bh(lock) \
    + do { spin_unlock(lock); local_bh_enable(); } while (0)
    +
    +#define read_unlock_irqrestore(lock, flags) do {\
    + _raw_read_unlock(lock); local_irq_restore(flags); preempt_enable(); \
    +} while (0)
    +
    +#define read_unlock_irq(lock) do { \
    + _raw_read_unlock(lock); local_irq_enable(); preempt_enable(); \
    +} while (0)
    +
    +#define read_unlock_bh(lock) do { \
    + read_unlock(lock); local_bh_enable(); \
    +} while (0)
    +
    +#define write_unlock_irqrestore(lock, flags) do { \
    + _raw_write_unlock(lock); local_irq_restore(flags); preempt_enable(); \
    +} while (0)
    +
    +#define write_unlock_irq(lock) do { \
    + _raw_write_unlock(lock); local_irq_enable(); preempt_enable(); \
    +} while (0)
    +
    +#define write_unlock_bh(lock) \
    + do { write_unlock(lock); local_bh_enable(); } while (0)
    +
    +#define spin_trylock_bh(lock) ({ int __r; local_bh_disable();\
    + __r = spin_trylock(lock); \
    + if (!__r) local_bh_enable(); \
    + __r; })
    +
    +/*
    + * Must define these before including other files, inline functions need them
    + */

    #include <linux/stringify.h>

    @@ -63,8 +104,11 @@
    #ifdef CONFIG_SMP
    #include <asm/spinlock.h>

    -#elif !defined(spin_lock_init) /* !SMP and spin_lock_init not previously
    - defined (e.g. by including asm/spinlock.h */
    +/*
    + * !CONFIG_SMP and spin_lock_init not previously defined
    + * (e.g. by including include/asm/spinlock.h)
    + */
    +#elif !defined(spin_lock_init)

    #ifndef CONFIG_PREEMPT
    # define atomic_dec_and_lock(atomic,lock) atomic_dec_and_test(atomic)
    @@ -73,16 +117,9 @@

    /*
    * Your basic spinlocks, allowing only a single CPU anywhere
    - *
    - * Most gcc versions have a nasty bug with empty initializers.
    */
    -#if (__GNUC__ > 2)
    - typedef struct { } spinlock_t;
    +typedef struct { } spinlock_t;
    # define SPIN_LOCK_UNLOCKED (spinlock_t) { }
    -#else
    - typedef struct { int gcc_is_buggy; } spinlock_t;
    -# define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
    -#endif

    #define spin_lock_init(lock) do { (void)(lock); } while(0)
    #define _raw_spin_lock(lock) (void)(lock) /* Not "unused variable". */
    @@ -100,16 +137,9 @@
    * can "mix" irq-safe locks - any writer needs to get a
    * irq-safe write-lock, but readers can get non-irqsafe
    * read-locks.
    - *
    - * Most gcc versions have a nasty bug with empty initializers.
    */
    -#if (__GNUC__ > 2)
    - typedef struct { } rwlock_t;
    - #define RW_LOCK_UNLOCKED (rwlock_t) { }
    -#else
    - typedef struct { int gcc_is_buggy; } rwlock_t;
    - #define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
    -#endif
    +typedef struct { } rwlock_t;
    +#define RW_LOCK_UNLOCKED (rwlock_t) { }

    #define rwlock_init(lock) do { } while(0)
    #define _raw_read_lock(lock) (void)(lock) /* Not "unused variable". */
    @@ -119,8 +149,6 @@

    #endif /* !SMP */

    -#ifdef CONFIG_PREEMPT
    -
    #define spin_lock(lock) \
    do { \
    preempt_disable(); \
    @@ -129,6 +157,7 @@

    #define spin_trylock(lock) ({preempt_disable(); _raw_spin_trylock(lock) ? \
    1 : ({preempt_enable(); 0;});})
    +
    #define spin_unlock(lock) \
    do { \
    _raw_spin_unlock(lock); \
    @@ -142,19 +171,6 @@
    #define write_trylock(lock) ({preempt_disable();_raw_write_trylock(lock) ? \
    1 : ({preempt_enable(); 0;});})

    -#else
    -
    -#define spin_lock(lock) _raw_spin_lock(lock)
    -#define spin_trylock(lock) _raw_spin_trylock(lock)
    -#define spin_unlock(lock) _raw_spin_unlock(lock)
    -
    -#define read_lock(lock) _raw_read_lock(lock)
    -#define read_unlock(lock) _raw_read_unlock(lock)
    -#define write_lock(lock) _raw_write_lock(lock)
    -#define write_unlock(lock) _raw_write_unlock(lock)
    -#define write_trylock(lock) _raw_write_trylock(lock)
    -#endif
    -
    /* "lock on reference count zero" */
    #ifndef ATOMIC_DEC_AND_LOCK
    #include <asm/atomic.h>
    -
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