Author: hselasky
Date: Tue Feb 21 13:23:53 2017
New Revision: 314043
URL: https://svnweb.freebsd.org/changeset/base/314043
Log:
Add support for LinuxKPI tasklets.
Tasklets are implemented using a taskqueue and a small statemachine on
top. The additional statemachine is required to ensure all LinuxKPI
tasklets get serialized. FreeBSD taskqueues do not guarantee
serialisation of its tasks, except when there is only one worker
thread configured.
MFC after: 1 week
Sponsored by: Mellanox Technologies
Added:
head/sys/compat/linuxkpi/common/include/linux/bottom_half.h (contents,
props changed)
head/sys/compat/linuxkpi/common/src/linux_tasklet.c (contents, props
changed)
Modified:
head/sys/compat/linuxkpi/common/include/linux/interrupt.h
head/sys/conf/files
head/sys/modules/linuxkpi/Makefile
Added: head/sys/compat/linuxkpi/common/include/linux/bottom_half.h
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/compat/linuxkpi/common/include/linux/bottom_half.h Tue Feb 21
13:23:53 2017 (r314043)
@@ -0,0 +1,34 @@
+/*-
+ * Copyright (c) 2017 Hans Petter Selasky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice unmodified, this list of conditions, and the following
+ * disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+#ifndef _LINUX_BOTTOM_HALF_H_
+#define _LINUX_BOTTOM_HALF_H_
+
+extern void local_bh_enable(void);
+extern void local_bh_disable(void);
+
+#endif /* _LINUX_BOTTOM_HALF_H_ */
Modified: head/sys/compat/linuxkpi/common/include/linux/interrupt.h
==============================================================================
--- head/sys/compat/linuxkpi/common/include/linux/interrupt.h Tue Feb 21
12:51:45 2017 (r314042)
+++ head/sys/compat/linuxkpi/common/include/linux/interrupt.h Tue Feb 21
13:23:53 2017 (r314043)
@@ -148,4 +148,25 @@ free_irq(unsigned int irq, void *device)
kfree(irqe);
}
+/*
+ * LinuxKPI tasklet support
+ */
+typedef void tasklet_func_t(unsigned long);
+
+struct tasklet_struct {
+ TAILQ_ENTRY(tasklet_struct) entry;
+ tasklet_func_t *func;
+ unsigned long data;
+};
+
+#define DECLARE_TASKLET(name, func, data) \
+struct tasklet_struct name = { { NULL, NULL }, func, data }
+
+#define tasklet_hi_schedule(t) tasklet_schedule(t)
+
+extern void tasklet_schedule(struct tasklet_struct *);
+extern void tasklet_kill(struct tasklet_struct *);
+extern void tasklet_init(struct tasklet_struct *, tasklet_func_t *,
+ unsigned long data);
+
#endif /* _LINUX_INTERRUPT_H_ */
Added: head/sys/compat/linuxkpi/common/src/linux_tasklet.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/sys/compat/linuxkpi/common/src/linux_tasklet.c Tue Feb 21 13:23:53
2017 (r314043)
@@ -0,0 +1,183 @@
+/*-
+ * Copyright (c) 2017 Hans Petter Selasky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice unmodified, this list of conditions, and the following
+ * disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/malloc.h>
+#include <sys/taskqueue.h>
+#include <sys/proc.h>
+#include <sys/sched.h>
+
+#include <linux/interrupt.h>
+#include <linux/bottom_half.h>
+#include <linux/compat.h>
+
+#define TASKLET_ST_IDLE 0
+#define TASKLET_ST_BUSY 1
+#define TASKLET_ST_EXEC 2
+#define TASKLET_ST_LOOP 3
+
+#define TASKLET_ST_CMPSET(ts, old, new) \
+ atomic_cmpset_ptr((volatile uintptr_t *)&(ts)->entry.tqe_prev, old, new)
+
+#define TASKLET_ST_SET(ts, new) \
+ atomic_store_rel_ptr((volatile uintptr_t *)&(ts)->entry.tqe_prev, new)
+
+#define TASKLET_ST_GET(ts) \
+ atomic_load_acq_ptr((volatile uintptr_t *)&(ts)->entry.tqe_prev)
+
+struct tasklet_worker {
+ struct mtx mtx;
+ TAILQ_HEAD(, tasklet_struct) head;
+ struct taskqueue *taskqueue;
+ struct task task;
+} __aligned(CACHE_LINE_SIZE);
+
+#define TASKLET_WORKER_LOCK(tw) mtx_lock(&(tw)->mtx)
+#define TASKLET_WORKER_UNLOCK(tw) mtx_unlock(&(tw)->mtx)
+
+static struct tasklet_worker tasklet_worker;
+
+static void
+tasklet_handler(void *arg, int pending)
+{
+ struct tasklet_worker *tw = (struct tasklet_worker *)arg;
+ struct tasklet_struct *ts;
+
+ linux_set_current(curthread);
+
+ TASKLET_WORKER_LOCK(tw);
+ local_bh_disable(); /* pin thread to CPU */
+ while (1) {
+ ts = TAILQ_FIRST(&tw->head);
+ if (ts == NULL)
+ break;
+ TAILQ_REMOVE(&tw->head, ts, entry);
+
+ TASKLET_WORKER_UNLOCK(tw);
+ do {
+ /* reset executing state */
+ TASKLET_ST_SET(ts, TASKLET_ST_EXEC);
+
+ ts->func(ts->data);
+
+ } while (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC,
TASKLET_ST_IDLE) == 0);
+ TASKLET_WORKER_LOCK(tw);
+ }
+ local_bh_enable(); /* unpin thread from CPU */
+ TASKLET_WORKER_UNLOCK(tw);
+}
+
+static void
+tasklet_subsystem_init(void *arg __unused)
+{
+ struct tasklet_worker *tw = &tasklet_worker;
+
+ tw->taskqueue = taskqueue_create("tasklet", M_WAITOK,
+ taskqueue_thread_enqueue, &tw->taskqueue);
+ mtx_init(&tw->mtx, "linux_tasklet", NULL, MTX_DEF);
+ TAILQ_INIT(&tw->head);
+ TASK_INIT(&tw->task, 0, tasklet_handler, tw);
+ taskqueue_start_threads(&tw->taskqueue, 1, PI_NET, "tasklet");
+}
+SYSINIT(linux_tasklet, SI_SUB_INIT_IF, SI_ORDER_THIRD, tasklet_subsystem_init,
NULL);
+
+static void
+tasklet_subsystem_uninit(void *arg __unused)
+{
+ struct tasklet_worker *tw = &tasklet_worker;
+
+ taskqueue_free(tw->taskqueue);
+ tw->taskqueue = NULL;
+ mtx_destroy(&tw->mtx);
+}
+SYSUNINIT(linux_tasklet, SI_SUB_INIT_IF, SI_ORDER_THIRD,
tasklet_subsystem_uninit, NULL);
+
+void
+tasklet_init(struct tasklet_struct *ts,
+ tasklet_func_t *func, unsigned long data)
+{
+ ts->entry.tqe_prev = NULL;
+ ts->entry.tqe_next = NULL;
+ ts->func = func;
+ ts->data = data;
+}
+
+void
+local_bh_enable(void)
+{
+ sched_unpin();
+}
+
+void
+local_bh_disable(void)
+{
+ sched_pin();
+}
+
+void
+tasklet_schedule(struct tasklet_struct *ts)
+{
+
+ if (TASKLET_ST_CMPSET(ts, TASKLET_ST_EXEC, TASKLET_ST_LOOP)) {
+ /* tasklet_handler() will loop */
+ } else if (TASKLET_ST_CMPSET(ts, TASKLET_ST_IDLE, TASKLET_ST_BUSY)) {
+ struct tasklet_worker *tw = &tasklet_worker;
+
+ /* tasklet_handler() was not queued */
+ TASKLET_WORKER_LOCK(tw);
+ /* enqueue tasklet */
+ TAILQ_INSERT_TAIL(&tw->head, ts, entry);
+ /* schedule worker */
+ taskqueue_enqueue(tw->taskqueue, &tw->task);
+ TASKLET_WORKER_UNLOCK(tw);
+ } else {
+ /*
+ * tasklet_handler() is already executing
+ *
+ * If the state is neither EXEC nor IDLE, it is either
+ * LOOP or BUSY. If the state changed between the two
+ * CMPSET's above the only possible transitions by
+ * elimination are LOOP->EXEC and BUSY->EXEC. If a
+ * EXEC->LOOP transition was missed that is not a
+ * problem because the callback function is then
+ * already about to be called again.
+ */
+ }
+}
+
+void
+tasklet_kill(struct tasklet_struct *ts)
+{
+
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "tasklet_kill() can
sleep");
+
+ /* wait until tasklet is no longer busy */
+ while (TASKLET_ST_GET(ts) != TASKLET_ST_IDLE)
+ pause("W", 1);
+}
Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files Tue Feb 21 12:51:45 2017 (r314042)
+++ head/sys/conf/files Tue Feb 21 13:23:53 2017 (r314043)
@@ -4272,6 +4272,8 @@ compat/linuxkpi/common/src/linux_kthread
compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_pci.c optional compat_linuxkpi pci \
compile-with "${LINUXKPI_C}"
+compat/linuxkpi/common/src/linux_tasklet.c optional compat_linuxkpi \
+ compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_idr.c optional compat_linuxkpi \
compile-with "${LINUXKPI_C}"
compat/linuxkpi/common/src/linux_radix.c optional compat_linuxkpi \
Modified: head/sys/modules/linuxkpi/Makefile
==============================================================================
--- head/sys/modules/linuxkpi/Makefile Tue Feb 21 12:51:45 2017
(r314042)
+++ head/sys/modules/linuxkpi/Makefile Tue Feb 21 13:23:53 2017
(r314043)
@@ -8,6 +8,7 @@ SRCS= linux_kmod.c \
linux_kthread.c \
linux_pci.c \
linux_radix.c \
+ linux_tasklet.c \
linux_idr.c \
linux_usb.c
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