diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 2510763295d09..084f6ad7b7a0a 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -219,10 +219,10 @@ - Three Main Types of Kernel Locks: Spinlocks, Mutexes and Semaphores + Two Main Types of Kernel Locks: Spinlocks and Mutexes - There are three main types of kernel locks. The fundamental type + There are two main types of kernel locks. The fundamental type is the spinlock (include/asm/spinlock.h), which is a very simple single-holder lock: if you can't get the @@ -239,14 +239,6 @@ can't sleep (see ), and so have to use a spinlock instead. - - The third type is a semaphore - (include/linux/semaphore.h): it - can have more than one holder at any time (the number decided at - initialization time), although it is most commonly used as a - single-holder lock (a mutex). If you can't get a semaphore, your - task will be suspended and later on woken up - just like for mutexes. - Neither type of lock is recursive: see . @@ -278,7 +270,7 @@ - Semaphores still exist, because they are required for + Mutexes still exist, because they are required for synchronization between user contexts, as we will see below. @@ -289,18 +281,17 @@ If you have a data structure which is only ever accessed from - user context, then you can use a simple semaphore - (linux/linux/semaphore.h) to protect it. This - is the most trivial case: you initialize the semaphore to the number - of resources available (usually 1), and call - down_interruptible() to grab the semaphore, and - up() to release it. There is also a - down(), which should be avoided, because it + user context, then you can use a simple mutex + (include/linux/mutex.h) to protect it. This + is the most trivial case: you initialize the mutex. Then you can + call mutex_lock_interruptible() to grab the mutex, + and mutex_unlock() to release it. There is also a + mutex_lock(), which should be avoided, because it will not return if a signal is received. - Example: linux/net/core/netfilter.c allows + Example: net/netfilter/nf_sockopt.c allows registration of new setsockopt() and getsockopt() calls, with nf_register_sockopt(). Registration and @@ -515,7 +506,7 @@ If you are in a process context (any syscall) and want to - lock other process out, use a semaphore. You can take a semaphore + lock other process out, use a mutex. You can take a mutex and sleep (copy_from_user*( or kmalloc(x,GFP_KERNEL)). @@ -662,7 +653,7 @@ SLBH SLBH SLBH -DI +MLI None @@ -692,8 +683,8 @@ spin_lock_bh -DI -down_interruptible +MLI +mutex_lock_interruptible @@ -1310,7 +1301,7 @@ as Alan Cox says, Lock data, not code. There is a coding bug where a piece of code tries to grab a spinlock twice: it will spin forever, waiting for the lock to - be released (spinlocks, rwlocks and semaphores are not + be released (spinlocks, rwlocks and mutexes are not recursive in Linux). This is trivial to diagnose: not a stay-up-five-nights-talk-to-fluffy-code-bunnies kind of problem. @@ -1335,7 +1326,7 @@ as Alan Cox says, Lock data, not code. This complete lockup is easy to diagnose: on SMP boxes the - watchdog timer or compiling with DEBUG_SPINLOCKS set + watchdog timer or compiling with DEBUG_SPINLOCK set (include/linux/spinlock.h) will show this up immediately when it happens. @@ -1558,7 +1549,7 @@ the amount of locking which needs to be done. Read/Write Lock Variants - Both spinlocks and semaphores have read/write variants: + Both spinlocks and mutexes have read/write variants: rwlock_t and struct rw_semaphore. These divide users into two classes: the readers and the writers. If you are only reading the data, you can get a read lock, but to write to @@ -1681,7 +1672,7 @@ the amount of locking which needs to be done. #include <linux/slab.h> #include <linux/string.h> +#include <linux/rcupdate.h> - #include <linux/semaphore.h> + #include <linux/mutex.h> #include <asm/errno.h> struct object @@ -1913,7 +1904,7 @@ machines due to caching. - put_user() + put_user() @@ -1927,13 +1918,13 @@ machines due to caching. - down_interruptible() and - down() + mutex_lock_interruptible() and + mutex_lock() - There is a down_trylock() which can be + There is a mutex_trylock() which can be used inside interrupt context, as it will not sleep. - up() will also never sleep. + mutex_unlock() will also never sleep. @@ -2023,7 +2014,7 @@ machines due to caching. Prior to 2.5, or when CONFIG_PREEMPT is unset, processes in user context inside the kernel would not - preempt each other (ie. you had that CPU until you have it up, + preempt each other (ie. you had that CPU until you gave it up, except for interrupts). With the addition of CONFIG_PREEMPT in 2.5.4, this changed: when in user context, higher priority tasks can "cut in": spinlocks diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 9f73587219e87..09c4a1efb8e3c 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -300,14 +300,6 @@ Who: ocfs2-devel@oss.oracle.com --------------------------- -What: asm/semaphore.h -When: 2.6.26 -Why: Implementation became generic; users should now include - linux/semaphore.h instead. -Who: Matthew Wilcox - ---------------------------- - What: SCTP_GET_PEER_ADDRS_NUM_OLD, SCTP_GET_PEER_ADDRS_OLD, SCTP_GET_LOCAL_ADDRS_NUM_OLD, SCTP_GET_LOCAL_ADDRS_OLD When: June 2009 diff --git a/arch/arm/mach-ns9xxx/clock.c b/arch/arm/mach-ns9xxx/clock.c index f8639161068f2..44ed20d4a388a 100644 --- a/arch/arm/mach-ns9xxx/clock.c +++ b/arch/arm/mach-ns9xxx/clock.c @@ -14,8 +14,8 @@ #include #include #include +#include -#include #include "clock.h" static LIST_HEAD(clocks); diff --git a/drivers/input/keyboard/hil_kbd.c b/drivers/input/keyboard/hil_kbd.c index adbf29f0169d8..71c1971abf808 100644 --- a/drivers/input/keyboard/hil_kbd.c +++ b/drivers/input/keyboard/hil_kbd.c @@ -37,6 +37,7 @@ #include #include #include +#include #include #include diff --git a/drivers/input/misc/hp_sdc_rtc.c b/drivers/input/misc/hp_sdc_rtc.c index 49d8abfe38fe0..daa9d4220331b 100644 --- a/drivers/input/misc/hp_sdc_rtc.c +++ b/drivers/input/misc/hp_sdc_rtc.c @@ -44,6 +44,7 @@ #include #include #include +#include MODULE_AUTHOR("Brian S. Julin "); MODULE_DESCRIPTION("HP i8042 SDC + MSM-58321 RTC Driver"); diff --git a/drivers/input/serio/hp_sdc.c b/drivers/input/serio/hp_sdc.c index 7b233a492ad51..aad664d5259fd 100644 --- a/drivers/input/serio/hp_sdc.c +++ b/drivers/input/serio/hp_sdc.c @@ -67,6 +67,7 @@ #include #include #include +#include #include #include #include diff --git a/include/asm-alpha/semaphore.h b/include/asm-alpha/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-alpha/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-arm/semaphore.h b/include/asm-arm/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-arm/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-avr32/semaphore.h b/include/asm-avr32/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-avr32/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-blackfin/semaphore.h b/include/asm-blackfin/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-blackfin/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-cris/semaphore.h b/include/asm-cris/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-cris/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-frv/semaphore.h b/include/asm-frv/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-frv/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-h8300/semaphore.h b/include/asm-h8300/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-h8300/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-ia64/semaphore.h b/include/asm-ia64/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-ia64/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-m32r/semaphore.h b/include/asm-m32r/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-m32r/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-m68k/semaphore.h b/include/asm-m68k/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-m68k/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-m68knommu/semaphore.h b/include/asm-m68knommu/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-m68knommu/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-mips/semaphore.h b/include/asm-mips/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-mips/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-mn10300/semaphore.h b/include/asm-mn10300/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-mn10300/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-parisc/semaphore.h b/include/asm-parisc/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-parisc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-powerpc/semaphore.h b/include/asm-powerpc/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-powerpc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-s390/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-sh/semaphore.h b/include/asm-sh/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-sh/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-sparc/semaphore.h b/include/asm-sparc/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-sparc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-sparc64/semaphore.h b/include/asm-sparc64/semaphore.h deleted file mode 100644 index 39362afde5fe2..0000000000000 --- a/include/asm-sparc64/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-um/semaphore.h b/include/asm-um/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-um/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-x86/semaphore.h b/include/asm-x86/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-x86/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/asm-xtensa/semaphore.h b/include/asm-xtensa/semaphore.h deleted file mode 100644 index d9b2034ed1d2e..0000000000000 --- a/include/asm-xtensa/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h index 9cae64b00d6bb..7415839ac890f 100644 --- a/include/linux/semaphore.h +++ b/include/linux/semaphore.h @@ -26,10 +26,8 @@ struct semaphore { .wait_list = LIST_HEAD_INIT((name).wait_list), \ } -#define __DECLARE_SEMAPHORE_GENERIC(name, count) \ - struct semaphore name = __SEMAPHORE_INITIALIZER(name, count) - -#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name, 1) +#define DECLARE_MUTEX(name) \ + struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1) static inline void sema_init(struct semaphore *sem, int val) {