4e7f640dfb
obtaining and releasing shared and exclusive locks. The algorithms for manipulating the lock cookie are very similar to that rwlocks. This patch also adds support for exclusive locks using the same algorithm as mutexes. A new sx_init_flags() function has been added so that optional flags can be specified to alter a given locks behavior. The flags include SX_DUPOK, SX_NOWITNESS, SX_NOPROFILE, and SX_QUITE which are all identical in nature to the similar flags for mutexes. Adaptive spinning on select locks may be enabled by enabling the ADAPTIVE_SX kernel option. Only locks initialized with the SX_ADAPTIVESPIN flag via sx_init_flags() will adaptively spin. The common cases for sx_slock(), sx_sunlock(), sx_xlock(), and sx_xunlock() are now performed inline in non-debug kernels. As a result, <sys/sx.h> now requires <sys/lock.h> to be included prior to <sys/sx.h>. The new kernel option SX_NOINLINE can be used to disable the aforementioned inlining in non-debug kernels. The size of struct sx has changed, so the kernel ABI is probably greatly disturbed. MFC after: 1 month Submitted by: attilio Tested by: kris, pjd
42 lines
967 B
C
42 lines
967 B
C
#ifndef __XFS_SUPPORT_MRLOCK_H__
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#define __XFS_SUPPORT_MRLOCK_H__
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#include <sys/types.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/sx.h>
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/*
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* Implement mrlocks on FreeBSD that work for XFS.
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* Map mrlock functions to corresponding equivalents in
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* sx.
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*/
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typedef struct sx mrlock_t;
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#define MR_ACCESS 1
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#define MR_UPDATE 2
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/*
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* Compatibility defines, not really used
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*/
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#define MRLOCK_BARRIER 0x1
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#define MRLOCK_ALLOW_EQUAL_PRI 0x8
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#define mrlock_init(lock, type, name, seq) sx_init(lock, name)
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#define mrtryaccess(lock) sx_try_slock(lock)
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#define mrtryupdate(lock) sx_try_xlock(lock)
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#define mraccess(lock) sx_slock(lock)
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#define mrupdate(lock) sx_xlock(lock)
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#define mrdemote(lock) sx_downgrade(lock)
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#define mrunlock(lock) sx_unlock(lock)
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#define mrfree(lock) do { \
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if (sx_xlocked(lock)) \
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sx_xunlock(lock); \
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sx_destroy(lock); \
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} while (0)
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int ismrlocked(mrlock_t *mrp, int type);
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#endif /* __XFS_SUPPORT_MRLOCK_H__ */
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