rm_rlock(9) manual page

`rm_init(struct rmlock rm, const char name)`
	Initialize the read-mostly lock rm. The name description is used solely for debugging purposes. This function must be called before any other operations on the lock.
`rm_init_flags(struct rmlock rm, const char name, int opts)`
	Similar to `rm_init()`, initialize the read-mostly lock rm with a set of optional flags. The opts arguments contains one or more of the following flags:

`RM_NOWITNESS`
	Instruct witness(4) to ignore this lock.
`RM_RECURSE`	Allow threads to recursively acquire shared locks for rm.
`RM_SLEEPABLE`
	Create a sleepable read-mostly lock.
`RM_NEW`	If the kernel has been compiled with option INVARIANTS, `rm_init_flags()` will assert that the rm has not been initialized multiple times without intervening calls to `rm_destroy()` unless this option is specified.
`RM_DUPOK`	witness(4) should not log messages about duplicate locks being acquired.

`rm_rlock(struct rmlock rm, struct rm_priotracker tracker)`
	Lock rm as a reader using tracker to track read owners of a lock for priority propagation. This data structure is only used internally by rmlock and must persist until `rm_runlock()` has been called. This data structure can be allocated on the stack since readers cannot sleep. If any thread holds this lock exclusively, the current thread blocks, and its priority is propagated to the exclusive holder. If the lock was initialized with the `RM_RECURSE` option the `rm_rlock()` function can be called when the current thread has already acquired reader access on rm.
`rm_try_rlock(struct rmlock rm, struct rm_priotracker tracker)`
	Try to lock rm as a reader. `rm_try_rlock()` will return 0 if the lock cannot be acquired immediately; otherwise, the lock will be acquired and a non-zero value will be returned. Note that `rm_try_rlock()` may fail even while the lock is not currently held by a writer. If the lock was initialized with the `RM_RECURSE` option, `rm_try_rlock()` will succeed if the current thread has already acquired reader access.
`rm_wlock(struct rmlock *rm)`
	Lock rm as a writer. If there are any shared owners of the lock, the current thread blocks. The `rm_wlock()` function cannot be called recursively.
`rm_runlock(struct rmlock rm, struct rm_priotracker tracker)`
	This function releases a shared lock previously acquired by `rm_rlock()`. The tracker argument must match the tracker argument used for acquiring the shared lock
`rm_wunlock(struct rmlock *rm)`
	This function releases an exclusive lock previously acquired by `rm_wlock()`.
`rm_destroy(struct rmlock *rm)`
	This functions destroys a lock previously initialized with `rm_init()`. The rm lock must be unlocked.
`rm_wowned(const struct rmlock *rm)`
	This function returns a non-zero value if the current thread owns an exclusive lock on rm.
`rm_sleep(void wchan, struct rmlock rm, int priority, const char *wmesg, int timo)`
	This function atomically releases rm while waiting for an event. The rm lock must be exclusively locked. For more details on the parameters to this function, see sleep(9).
`rm_assert(struct rmlock *rm, int what)`
	This function asserts that the rm lock is in the state specified by what. If the assertions are not true and the kernel is compiled with options INVARIANTS and options INVARIANT_SUPPORT, the kernel will panic. Currently the following base assertions are supported:

`RA_LOCKED`	Assert that current thread holds either a shared or exclusive lock of rm.
`RA_RLOCKED`	Assert that current thread holds a shared lock of rm.
`RA_WLOCKED`	Assert that current thread holds an exclusive lock of rm.
`RA_UNLOCKED`
	Assert that current thread holds neither a shared nor exclusive lock of rm.

In addition, one of the following optional flags may be specified with RA_LOCKED, RA_RLOCKED, or RA_WLOCKED:

RA_RECURSED Assert that the current thread holds a recursive lock of rm.

RA_NOTRECURSED

Assert that the current thread does not hold a recursive lock of rm.

rms_init(struct rmslock *rms, const char *name)

Initialize the sleepable read-mostly lock rms. The name description is used as wmesg parameter to the msleep(9) routine. This function must be called before any other operations on the lock.

rms_rlock(struct rmlock *rm)

Lock rms as a reader. If any thread holds this lock exclusively, the current thread blocks.

rms_wlock(struct rmslock *rms)

Lock rms as a writer. If the lock is already taken, the current thread blocks. The rms_wlock() function cannot be called recursively.

rms_runlock(struct rmslock *rms)

This function releases a shared lock previously acquired by rms_rlock().

rms_wunlock(struct rmslock *rms)

This function releases an exclusive lock previously acquired by rms_wlock().

rms_destroy(struct rmslock *rms)

This functions destroys a lock previously initialized with rms_init(). The rms lock must be unlocked.

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Manual Pages — RMLOCK

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Macros and Functions

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`RA_RECURSED`	Assert that the current thread holds a recursive lock of rm.
`RA_NOTRECURSED`
	Assert that the current thread does not hold a recursive lock of rm.

`rms_init(struct rmslock rms, const char name)`
	Initialize the sleepable read-mostly lock rms. The name description is used as wmesg parameter to the msleep(9) routine. This function must be called before any other operations on the lock.
`rms_rlock(struct rmlock *rm)`
	Lock rms as a reader. If any thread holds this lock exclusively, the current thread blocks.
`rms_wlock(struct rmslock *rms)`
	Lock rms as a writer. If the lock is already taken, the current thread blocks. The `rms_wlock()` function cannot be called recursively.
`rms_runlock(struct rmslock *rms)`
	This function releases a shared lock previously acquired by `rms_rlock()`.
`rms_wunlock(struct rmslock *rms)`
	This function releases an exclusive lock previously acquired by `rms_wlock()`.
`rms_destroy(struct rmslock *rms)`
	This functions destroys a lock previously initialized with `rms_init()`. The rms lock must be unlocked.