RW_RDLOCK(D3)

NAME
     RW_RDLOCK - acquire a read/write lock in read mode

SYNOPSIS
     #include <sys/ksynch.h>
     #include <sys/ddi.h>
     void RW_RDLOCK(rwlock_t *lockp);

   Arguments
     lockp     Pointer to the read/write lock to be acquired.

DESCRIPTION
     RW_RDLOCK acquires the read/write lock specified by lockp in read mode.
     If the lock is not immediately available in read mode, the caller is put
     to sleep (the caller's execution is suspended and other processes may be
     scheduled) until the lock becomes available to the caller, at which point
     the caller wakes up and returns with the lock held.  A read/write lock is
     available in read mode when the lock is not held by any context in write
     mode.

     The caller will not be interrupted by signals while asleep waiting to
     acquire the read/write lock.

   Return Values
     None

   Level
     Base only.

   Synchronization Constraints
     Can sleep.

     Driver-defined basic locks may not be held across calls to this function.

     Driver-defined sleep locks may be held across calls to this function
     subject to the recursion restrictions described below.

   Warnings
     Multiple calls to RW_RDLOCK may be made to acquire the same lock, but a
     context that holds a read/write lock in write mode cannot acquire the
     same lock in read mode, and vice versa.

REFERENCES
     RW_ALLOC(D3), RW_INIT(D3), RW_DEALLOC(D3), RW_DESTROY(D3), RW_WRLOCK(D3),
     RW_UNLOCK(D3),