diff options
29 files changed, 30 insertions, 68 deletions
diff --git a/Documentation/DocBook/kernel-locking.tmpl b/Documentation/DocBook/kernel-locking.tmpl index 2510763295d..084f6ad7b7a 100644 --- a/Documentation/DocBook/kernel-locking.tmpl +++ b/Documentation/DocBook/kernel-locking.tmpl @@ -219,10 +219,10 @@ </para> <sect1 id="lock-intro"> - <title>Three Main Types of Kernel Locks: Spinlocks, Mutexes and Semaphores</title> + <title>Two Main Types of Kernel Locks: Spinlocks and Mutexes</title> <para> - 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 (<filename class="headerfile">include/asm/spinlock.h</filename>), which is a very simple single-holder lock: if you can't get the @@ -240,14 +240,6 @@ use a spinlock instead. </para> <para> - The third type is a semaphore - (<filename class="headerfile">include/linux/semaphore.h</filename>): 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. - </para> - <para> Neither type of lock is recursive: see <xref linkend="deadlock"/>. </para> @@ -278,7 +270,7 @@ </para> <para> - Semaphores still exist, because they are required for + Mutexes still exist, because they are required for synchronization between <firstterm linkend="gloss-usercontext">user contexts</firstterm>, as we will see below. </para> @@ -289,18 +281,17 @@ <para> If you have a data structure which is only ever accessed from - user context, then you can use a simple semaphore - (<filename>linux/linux/semaphore.h</filename>) to protect it. This - is the most trivial case: you initialize the semaphore to the number - of resources available (usually 1), and call - <function>down_interruptible()</function> to grab the semaphore, and - <function>up()</function> to release it. There is also a - <function>down()</function>, which should be avoided, because it + user context, then you can use a simple mutex + (<filename>include/linux/mutex.h</filename>) to protect it. This + is the most trivial case: you initialize the mutex. Then you can + call <function>mutex_lock_interruptible()</function> to grab the mutex, + and <function>mutex_unlock()</function> to release it. There is also a + <function>mutex_lock()</function>, which should be avoided, because it will not return if a signal is received. </para> <para> - Example: <filename>linux/net/core/netfilter.c</filename> allows + Example: <filename>net/netfilter/nf_sockopt.c</filename> allows registration of new <function>setsockopt()</function> and <function>getsockopt()</function> calls, with <function>nf_register_sockopt()</function>. Registration and @@ -515,7 +506,7 @@ <listitem> <para> 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 (<function>copy_from_user*(</function> or <function>kmalloc(x,GFP_KERNEL)</function>). </para> @@ -662,7 +653,7 @@ <entry>SLBH</entry> <entry>SLBH</entry> <entry>SLBH</entry> -<entry>DI</entry> +<entry>MLI</entry> <entry>None</entry> </row> @@ -692,8 +683,8 @@ <entry>spin_lock_bh</entry> </row> <row> -<entry>DI</entry> -<entry>down_interruptible</entry> +<entry>MLI</entry> +<entry>mutex_lock_interruptible</entry> </row> </tbody> @@ -1310,7 +1301,7 @@ as Alan Cox says, <quote>Lock data, not code</quote>. <para> 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, <quote>Lock data, not code</quote>. <para> This complete lockup is easy to diagnose: on SMP boxes the - watchdog timer or compiling with <symbol>DEBUG_SPINLOCKS</symbol> set + watchdog timer or compiling with <symbol>DEBUG_SPINLOCK</symbol> set (<filename>include/linux/spinlock.h</filename>) will show this up immediately when it happens. </para> @@ -1558,7 +1549,7 @@ the amount of locking which needs to be done. <title>Read/Write Lock Variants</title> <para> - Both spinlocks and semaphores have read/write variants: + Both spinlocks and mutexes have read/write variants: <type>rwlock_t</type> and <structname>struct rw_semaphore</structname>. 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. </listitem> <listitem> <para> - <function> put_user()</function> + <function>put_user()</function> </para> </listitem> </itemizedlist> @@ -1927,13 +1918,13 @@ machines due to caching. <listitem> <para> - <function>down_interruptible()</function> and - <function>down()</function> + <function>mutex_lock_interruptible()</function> and + <function>mutex_lock()</function> </para> <para> - There is a <function>down_trylock()</function> which can be + There is a <function>mutex_trylock()</function> which can be used inside interrupt context, as it will not sleep. - <function>up()</function> will also never sleep. + <function>mutex_unlock()</function> will also never sleep. </para> </listitem> </itemizedlist> @@ -2023,7 +2014,7 @@ machines due to caching. <para> Prior to 2.5, or when <symbol>CONFIG_PREEMPT</symbol> 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 <symbol>CONFIG_PREEMPT</symbol> 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 9f73587219e..09c4a1efb8e 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 <willy@linux.intel.com> - ---------------------------- - 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 f8639161068..44ed20d4a38 100644 --- a/arch/arm/mach-ns9xxx/clock.c +++ b/arch/arm/mach-ns9xxx/clock.c @@ -14,8 +14,8 @@ #include <linux/clk.h> #include <linux/string.h> #include <linux/platform_device.h> +#include <linux/semaphore.h> -#include <asm/semaphore.h> #include "clock.h" static LIST_HEAD(clocks); diff --git a/drivers/input/keyboard/hil_kbd.c b/drivers/input/keyboard/hil_kbd.c index adbf29f0169..71c1971abf8 100644 --- a/drivers/input/keyboard/hil_kbd.c +++ b/drivers/input/keyboard/hil_kbd.c @@ -37,6 +37,7 @@ #include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> +#include <linux/semaphore.h> #include <linux/slab.h> #include <linux/pci_ids.h> diff --git a/drivers/input/misc/hp_sdc_rtc.c b/drivers/input/misc/hp_sdc_rtc.c index 49d8abfe38f..daa9d422033 100644 --- a/drivers/input/misc/hp_sdc_rtc.c +++ b/drivers/input/misc/hp_sdc_rtc.c @@ -44,6 +44,7 @@ #include <linux/proc_fs.h> #include <linux/poll.h> #include <linux/rtc.h> +#include <linux/semaphore.h> MODULE_AUTHOR("Brian S. Julin <bri@calyx.com>"); 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 7b233a492ad..aad664d5259 100644 --- a/drivers/input/serio/hp_sdc.c +++ b/drivers/input/serio/hp_sdc.c @@ -67,6 +67,7 @@ #include <linux/module.h> #include <linux/ioport.h> #include <linux/time.h> +#include <linux/semaphore.h> #include <linux/slab.h> #include <linux/hil.h> #include <linux/semaphore.h> diff --git a/include/asm-alpha/semaphore.h b/include/asm-alpha/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-alpha/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-arm/semaphore.h b/include/asm-arm/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-arm/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-avr32/semaphore.h b/include/asm-avr32/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-avr32/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-blackfin/semaphore.h b/include/asm-blackfin/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-blackfin/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-cris/semaphore.h b/include/asm-cris/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-cris/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-frv/semaphore.h b/include/asm-frv/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-frv/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-h8300/semaphore.h b/include/asm-h8300/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-h8300/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-ia64/semaphore.h b/include/asm-ia64/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-ia64/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-m32r/semaphore.h b/include/asm-m32r/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-m32r/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-m68k/semaphore.h b/include/asm-m68k/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-m68k/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-m68knommu/semaphore.h b/include/asm-m68knommu/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-m68knommu/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-mips/semaphore.h b/include/asm-mips/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-mips/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-mn10300/semaphore.h b/include/asm-mn10300/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-mn10300/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-parisc/semaphore.h b/include/asm-parisc/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-parisc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-powerpc/semaphore.h b/include/asm-powerpc/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-powerpc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-s390/semaphore.h b/include/asm-s390/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-s390/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-sh/semaphore.h b/include/asm-sh/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-sh/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-sparc/semaphore.h b/include/asm-sparc/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-sparc/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-sparc64/semaphore.h b/include/asm-sparc64/semaphore.h deleted file mode 100644 index 39362afde5f..00000000000 --- a/include/asm-sparc64/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <asm-sparc/semaphore.h> diff --git a/include/asm-um/semaphore.h b/include/asm-um/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-um/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-x86/semaphore.h b/include/asm-x86/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-x86/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/asm-xtensa/semaphore.h b/include/asm-xtensa/semaphore.h deleted file mode 100644 index d9b2034ed1d..00000000000 --- a/include/asm-xtensa/semaphore.h +++ /dev/null @@ -1 +0,0 @@ -#include <linux/semaphore.h> diff --git a/include/linux/semaphore.h b/include/linux/semaphore.h index 9cae64b00d6..7415839ac89 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) { |