Commit e5236836 authored by Warner Losh's avatar Warner Losh
Browse files

config_intrhook: provide config_intrhook_drain

config_intrhook_drain will remove the hook from the list as
config_intrhook_disestablish does if the hook hasn't been called.  If it has,
config_intrhook_drain will wait for the hook to be disestablished in the normal
course (or expedited, it's up to the driver to decide how and when
to call config_intrhook_disestablish).

This is intended for removable devices that use config_intrhook and might be
attached early in boot, but that may be removed before the kernel can call the
config_intrhook or before it ends. To prevent all races, the detach routine will
need to call config_intrhook_train.

Sponsored by:		Netflix, Inc
Reviewed by:		jhb, mav, gde (in D29006 for man page)
Differential Revision:	https://reviews.freebsd.org/D29005
parent dc0119c2
......@@ -859,6 +859,7 @@ MLINKS+=condvar.9 cv_broadcast.9 \
condvar.9 cv_wait_unlock.9 \
condvar.9 cv_wmesg.9
MLINKS+=config_intrhook.9 config_intrhook_disestablish.9 \
config_intrhook.9 config_intrhook_drain.9 \
config_intrhook.9 config_intrhook_establish.9 \
config_intrhook.9 config_intrhook_oneshot.9
MLINKS+=contigmalloc.9 contigmalloc_domainset.9 \
......
......@@ -26,7 +26,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd August 10, 2017
.Dd March 8, 2021
.Dt CONFIG_INTRHOOK 9
.Os
.Sh NAME
......@@ -40,6 +40,8 @@ but before root is mounted
.Fn config_intrhook_establish "struct intr_config_hook *hook"
.Ft void
.Fn config_intrhook_disestablish "struct intr_config_hook *hook"
.Ft int
.Fn config_intrhook_drain "struct intr_config_hook *hook"
.Ft void
.Fn config_intrhook_oneshot "ich_func_t func" "void *arg"
.Sh DESCRIPTION
......@@ -55,6 +57,23 @@ The
function removes the entry from the hook queue.
.Pp
The
.Fn config_intrhook_drain
function removes the entry from the hook queue in a safe way.
If the hook is not currently active it removes
.Fa hook
from the hook queue and returns
.Vt ICHS_QUEUED .
If the hook is active, it waits for the hook to complete before returning
.Vt ICHS_RUNNING .
If the hook has previously completed, it returns
.Vt ICHS_DONE .
Because a
.Vt config_intrhook
is undefined prior to
.Fn config_intrhook_establish ,
this function may only be called after that function has returned.
.Pp
The
.Fn config_intrhook_oneshot
function schedules a function to be run as described for
.Fn config_intrhook_establish ;
......
......@@ -138,6 +138,7 @@ run_interrupt_driven_config_hooks()
while (next_to_notify != NULL) {
hook_entry = next_to_notify;
next_to_notify = STAILQ_NEXT(hook_entry, ich_links);
hook_entry->ich_state = ICHS_RUNNING;
mtx_unlock(&intr_config_hook_lock);
(*hook_entry->ich_func)(hook_entry->ich_arg);
mtx_lock(&intr_config_hook_lock);
......@@ -199,6 +200,7 @@ config_intrhook_establish(struct intr_config_hook *hook)
STAILQ_INSERT_TAIL(&intr_config_hook_list, hook, ich_links);
if (next_to_notify == NULL)
next_to_notify = hook;
hook->ich_state = ICHS_QUEUED;
mtx_unlock(&intr_config_hook_lock);
if (cold == 0)
/*
......@@ -226,12 +228,11 @@ config_intrhook_oneshot(ich_func_t func, void *arg)
config_intrhook_establish(&ohook->och_hook);
}
void
config_intrhook_disestablish(struct intr_config_hook *hook)
static void
config_intrhook_disestablish_locked(struct intr_config_hook *hook)
{
struct intr_config_hook *hook_entry;
mtx_lock(&intr_config_hook_lock);
STAILQ_FOREACH(hook_entry, &intr_config_hook_list, ich_links)
if (hook_entry == hook)
break;
......@@ -245,8 +246,51 @@ config_intrhook_disestablish(struct intr_config_hook *hook)
TSRELEASE("config hooks");
/* Wakeup anyone watching the list */
hook->ich_state = ICHS_DONE;
wakeup(&intr_config_hook_list);
}
void
config_intrhook_disestablish(struct intr_config_hook *hook)
{
mtx_lock(&intr_config_hook_lock);
config_intrhook_disestablish_locked(hook);
mtx_unlock(&intr_config_hook_lock);
}
int
config_intrhook_drain(struct intr_config_hook *hook)
{
mtx_lock(&intr_config_hook_lock);
/*
* The config hook has completed, so just return.
*/
if (hook->ich_state == ICHS_DONE) {
mtx_unlock(&intr_config_hook_lock);
return (ICHS_DONE);
}
/*
* The config hook hasn't started running, just call disestablish.
*/
if (hook->ich_state == ICHS_QUEUED) {
config_intrhook_disestablish_locked(hook);
mtx_unlock(&intr_config_hook_lock);
return (ICHS_QUEUED);
}
/*
* The config hook is running, so wait for it to complete and return.
*/
while (hook->ich_state != ICHS_DONE) {
if (msleep(&intr_config_hook_list, &intr_config_hook_lock,
0, "confhd", hz) == EWOULDBLOCK) {
// XXX do I whine?
}
}
mtx_unlock(&intr_config_hook_lock);
return (ICHS_RUNNING);
}
#ifdef DDB
......
......@@ -467,13 +467,17 @@ typedef void (*ich_func_t)(void *_arg);
struct intr_config_hook {
STAILQ_ENTRY(intr_config_hook) ich_links;
uintptr_t ich_padding;
uintptr_t ich_state;
#define ICHS_QUEUED 0x1
#define ICHS_RUNNING 0x2
#define ICHS_DONE 0x3
ich_func_t ich_func;
void *ich_arg;
};
int config_intrhook_establish(struct intr_config_hook *hook);
void config_intrhook_disestablish(struct intr_config_hook *hook);
int config_intrhook_drain(struct intr_config_hook *hook);
void config_intrhook_oneshot(ich_func_t _func, void *_arg);
#endif /* !_SYS_KERNEL_H_*/
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