D3390.id7966.diff
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	Index: share/man/man9/kproc.9
	===================================================================
	--- share/man/man9/kproc.9
	+++ share/man/man9/kproc.9
	@@ -179,11 +179,12 @@
	The
	.Fa ecode
	argument specifies the exit status of the process.
	-While exiting, the function
	-.Xr exit1 9
	-will initiate a call to
	-.Xr wakeup 9
	-on the process handle.
	+A
	+.Fn wakeup
	+is issued on the proc pointer which can be used by callers to know
	+when the called function is no longer running.
	+See the EXAMPLE section for how to use this to ensure that a module
	+is unloaded safely.
	.Pp
	The
	.Fn kproc_resume ,
	@@ -321,6 +322,40 @@
	}
	}
	.Ed
	+.Pp
	+When the process is started as part of a module, the module needs to ensure
	+that the module's code is no longer executing.
	+.Bd -literal -offset indent
	+struct mtx proc_interlock;
	+volatile int proc_intervar;
	+struct proc procptr; / prointer from kproc_create */
	+
	+void
	+kproc_fun(void *arg)
	+{
	+
	+ for (;;) {
	+ mtx_lock(&proc_interlock);
	+ if (proc_intervar)
	+ break;
	+ mtx_unlock(&proc_interlock);
	+
	+ /* do work */
	+ }
	+
	+ kproc_exit(0);
	+}
	+
	+void
	+unloadmod(void)
	+{
	+
	+ mtx_lock(&proc_interlock);
	+ proc_intervar = 1;
	+ mtx_sleep(procptr, &proc_interlock, PDROP, "procexit", 0);
	+ /* kproc_fun has returned, and module is safe to unload. */
	+}
	+.Ed
	.Sh ERRORS
	The
	.Fn kproc_resume