[PATCH v2 4/6] bus: mhi: core: Introduce debugfs entries and counters for MHI
From: Bhaumik Bhatt
Date: Tue May 12 2020 - 13:42:38 EST
Introduce debugfs entries to show state, channel, and event ring
information. Add MHI state counters to keep track of the state changes
on the device and add a helper API mhi_to_physical() to see the physical
address from debugfs. Also, allow the host to trigger a device reset,
issue bus or device votes, and change the MHI timeout to help in debug.
Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
---
drivers/bus/mhi/Kconfig | 8 +
drivers/bus/mhi/core/Makefile | 5 +-
drivers/bus/mhi/core/debugfs.c | 431 ++++++++++++++++++++++++++++++++++++++++
drivers/bus/mhi/core/init.c | 7 +
drivers/bus/mhi/core/internal.h | 24 +++
drivers/bus/mhi/core/pm.c | 4 +
include/linux/mhi.h | 4 +
7 files changed, 480 insertions(+), 3 deletions(-)
create mode 100644 drivers/bus/mhi/core/debugfs.c
diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
index a8bd9bd..6a217ff 100644
--- a/drivers/bus/mhi/Kconfig
+++ b/drivers/bus/mhi/Kconfig
@@ -12,3 +12,11 @@ config MHI_BUS
communication protocol used by the host processors to control
and communicate with modem devices over a high speed peripheral
bus or shared memory.
+
+config MHI_BUS_DEBUG
+ bool "Debugfs support for the MHI bus"
+ depends on MHI_BUS && DEBUG_FS
+ help
+ Enable debugfs support for use with the MHI transport. Allows
+ reading and/or modifying some values within the MHI controller
+ for debug and test purposes.
diff --git a/drivers/bus/mhi/core/Makefile b/drivers/bus/mhi/core/Makefile
index 66e2700..460a548 100644
--- a/drivers/bus/mhi/core/Makefile
+++ b/drivers/bus/mhi/core/Makefile
@@ -1,3 +1,2 @@
-obj-$(CONFIG_MHI_BUS) := mhi.o
-
-mhi-y := init.o main.o pm.o boot.o
+obj-$(CONFIG_MHI_BUS) := init.o main.o pm.o boot.o
+obj-$(CONFIG_MHI_BUS_DEBUG) += debugfs.o
diff --git a/drivers/bus/mhi/core/debugfs.c b/drivers/bus/mhi/core/debugfs.c
new file mode 100644
index 0000000..fa70666
--- /dev/null
+++ b/drivers/bus/mhi/core/debugfs.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020, The Linux Foundation. All rights reserved.
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/mhi.h>
+#include "internal.h"
+
+static int mhi_debugfs_states_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+
+ /* states */
+ seq_printf(m, "PM state:%s Device:%s MHI state:%s EE:%s wake:%s\n",
+ to_mhi_pm_state_str(mhi_cntrl->pm_state),
+ mhi_is_active(mhi_cntrl) ? "Active" : "Inactive",
+ TO_MHI_STATE_STR(mhi_cntrl->dev_state),
+ TO_MHI_EXEC_STR(mhi_cntrl->ee),
+ mhi_cntrl->wake_set ? "true" : "false");
+
+ /* counters */
+ seq_printf(m, "M0:%u M2:%u M3:%u M3_Fast:%u", mhi_cntrl->M0,
+ mhi_cntrl->M2, mhi_cntrl->M3, mhi_cntrl->M3_fast);
+
+ seq_printf(m, " device wake:%u pending packets:%u\n",
+ atomic_read(&mhi_cntrl->dev_wake),
+ atomic_read(&mhi_cntrl->pending_pkts));
+
+ return 0;
+}
+
+static int mhi_debugfs_events_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_event *mhi_event;
+ struct mhi_event_ctxt *er_ctxt;
+ int i;
+
+ if (!mhi_is_active(mhi_cntrl)) {
+ seq_puts(m, "Device not ready\n");
+ return -ENODEV;
+ }
+
+ er_ctxt = mhi_cntrl->mhi_ctxt->er_ctxt;
+ mhi_event = mhi_cntrl->mhi_event;
+ for (i = 0; i < mhi_cntrl->total_ev_rings;
+ i++, er_ctxt++, mhi_event++) {
+ struct mhi_ring *ring = &mhi_event->ring;
+
+ if (mhi_event->offload_ev) {
+ seq_printf(m, "Index:%d is an offload event ring\n", i);
+ continue;
+ }
+
+ seq_printf(m, "Index:%d intmod count:%lu time:%lu",
+ i, (er_ctxt->intmod & EV_CTX_INTMODC_MASK) >>
+ EV_CTX_INTMODC_SHIFT,
+ (er_ctxt->intmod & EV_CTX_INTMODT_MASK) >>
+ EV_CTX_INTMODT_SHIFT);
+
+ seq_printf(m, " base:0x%0llx len:0x%llx", er_ctxt->rbase,
+ er_ctxt->rlen);
+
+ seq_printf(m,
+ " rp:0x%llx wp:0x%llx local rp:0x%llx db:0x%llx\n",
+ er_ctxt->rp, er_ctxt->wp, (u64)ring->rp,
+ mhi_event->db_cfg.db_val);
+ }
+
+ return 0;
+}
+
+static int mhi_debugfs_channels_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_chan *mhi_chan;
+ struct mhi_chan_ctxt *chan_ctxt;
+ int i;
+
+ if (!mhi_is_active(mhi_cntrl)) {
+ seq_puts(m, "Device not ready\n");
+ return -ENODEV;
+ }
+
+ mhi_chan = mhi_cntrl->mhi_chan;
+ chan_ctxt = mhi_cntrl->mhi_ctxt->chan_ctxt;
+ for (i = 0; i < mhi_cntrl->max_chan; i++, chan_ctxt++, mhi_chan++) {
+ struct mhi_ring *ring = &mhi_chan->tre_ring;
+
+ if (mhi_chan->offload_ch) {
+ seq_printf(m, "%s(%u) is an offload channel\n",
+ mhi_chan->name, mhi_chan->chan);
+ continue;
+ }
+
+ if (!mhi_chan->mhi_dev)
+ continue;
+
+ seq_printf(m,
+ "%s(%u) state:0x%lx brstmode:0x%lx pollcfg:0x%lx",
+ mhi_chan->name, mhi_chan->chan, (chan_ctxt->chcfg &
+ CHAN_CTX_CHSTATE_MASK) >> CHAN_CTX_CHSTATE_SHIFT,
+ (chan_ctxt->chcfg & CHAN_CTX_BRSTMODE_MASK) >>
+ CHAN_CTX_BRSTMODE_SHIFT, (chan_ctxt->chcfg &
+ CHAN_CTX_POLLCFG_MASK) >> CHAN_CTX_POLLCFG_SHIFT);
+
+ seq_printf(m, " type:0x%x event ring:%u", chan_ctxt->chtype,
+ chan_ctxt->erindex);
+
+ seq_printf(m, " base:0x%llx len:0x%llx wp:0x%llx",
+ chan_ctxt->rbase, chan_ctxt->rlen, chan_ctxt->wp);
+
+ seq_printf(m, " local rp:0x%llx local wp:0x%llx db:0x%llx\n",
+ (u64)ring->rp, (u64)ring->wp,
+ mhi_chan->db_cfg.db_val);
+ }
+
+ return 0;
+}
+
+static int mhi_device_votes_show(struct device *dev, void *data)
+{
+ struct mhi_device *mhi_dev;
+
+ if (dev->bus != &mhi_bus_type)
+ return 0;
+
+ mhi_dev = to_mhi_device(dev);
+
+ seq_printf((struct seq_file *)data, "%s: device:%u, bus:%u\n",
+ mhi_dev->name, atomic_read(&mhi_dev->dev_vote),
+ atomic_read(&mhi_dev->bus_vote));
+
+ return 0;
+}
+
+static int mhi_debugfs_votes_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+
+ if (!mhi_is_active(mhi_cntrl)) {
+ seq_puts(m, "Device not ready\n");
+ return -ENODEV;
+ }
+
+ device_for_each_child(mhi_cntrl->cntrl_dev, m, mhi_device_votes_show);
+
+ return 0;
+}
+
+static int mhi_debugfs_bus_vote_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+
+ if (!mhi_is_active(mhi_cntrl)) {
+ seq_puts(m, "Device not ready\n");
+ return -ENODEV;
+ }
+
+ seq_printf(m, "Votes: %d\n%s\n", atomic_read(&mhi_dev->bus_vote),
+ "Usage: echo get/put > bus_vote for vote/unvote");
+
+ return 0;
+}
+
+static ssize_t mhi_debugfs_bus_vote_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct seq_file *m = file->private_data;
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+ char buf[32];
+ int ret = -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+ return -EFAULT;
+
+ if (!strncmp(buf, "get", 3)) {
+ ret = mhi_device_get_sync(mhi_dev, MHI_VOTE_BUS);
+ } else if (!strncmp(buf, "put", 3)) {
+ mhi_device_put(mhi_dev, MHI_VOTE_BUS);
+ ret = 0;
+ }
+
+ return ret ? ret : count;
+}
+
+static int mhi_debugfs_device_vote_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+
+ if (!mhi_is_active(mhi_cntrl)) {
+ seq_puts(m, "Device not ready\n");
+ return -ENODEV;
+ }
+
+ seq_printf(m,
+ "Votes: %d\n%s\n", atomic_read(&mhi_dev->dev_vote),
+ "Usage: echo get/put > device_vote for vote/unvote");
+
+ return 0;
+}
+
+static ssize_t mhi_debugfs_device_vote_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct seq_file *m = file->private_data;
+ struct mhi_controller *mhi_cntrl = m->private;
+ struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+ char buf[32];
+ int ret = -EINVAL;
+
+ if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
+ return -EFAULT;
+
+ if (!strncmp(buf, "get", 3)) {
+ ret = mhi_device_get_sync(mhi_dev, MHI_VOTE_DEVICE);
+ } else if (!strncmp(buf, "put", 3)) {
+ mhi_device_put(mhi_dev, MHI_VOTE_DEVICE);
+ ret = 0;
+ }
+
+ return ret ? ret : count;
+}
+
+static int mhi_debugfs_timeout_ms_show(struct seq_file *m, void *d)
+{
+ struct mhi_controller *mhi_cntrl = m->private;
+
+ seq_printf(m, "%u ms\n", mhi_cntrl->timeout_ms);
+
+ return 0;
+}
+
+static ssize_t mhi_debugfs_timeout_ms_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ struct seq_file *m = file->private_data;
+ struct mhi_controller *mhi_cntrl = m->private;
+ u32 timeout_ms;
+
+ if (kstrtou32_from_user(ubuf, count, 0, &timeout_ms))
+ return -EINVAL;
+
+ mhi_cntrl->timeout_ms = timeout_ms;
+
+ return count;
+}
+
+static int mhi_debugfs_trigger_reset(void *data, u64 val)
+{
+ struct mhi_controller *mhi_cntrl = data;
+ struct mhi_device *mhi_dev = mhi_cntrl->mhi_dev;
+ struct device *dev = &mhi_dev->dev;
+ enum mhi_pm_state cur_state;
+ int ret = -EIO;
+
+ if (!mhi_is_active(mhi_cntrl))
+ return -ENODEV;
+
+ if (!val)
+ return -EINVAL;
+
+ ret = mhi_device_get_sync(mhi_dev, MHI_VOTE_DEVICE);
+ if (ret) {
+ dev_err(dev, "Device did not enter M0 state, MHI:%s, PM:%s\n",
+ TO_MHI_STATE_STR(mhi_cntrl->dev_state),
+ to_mhi_pm_state_str(mhi_cntrl->pm_state));
+ return ret;
+ }
+
+ if (mhi_cntrl->rddm_image) {
+ ret = mhi_force_rddm_mode(mhi_cntrl);
+ goto exit_mhi_trigger_reset;
+ }
+
+ write_lock_irq(&mhi_cntrl->pm_lock);
+ cur_state = mhi_tryset_pm_state(mhi_cntrl, MHI_PM_SYS_ERR_DETECT);
+ write_unlock_irq(&mhi_cntrl->pm_lock);
+
+ if (cur_state != MHI_PM_SYS_ERR_DETECT)
+ goto exit_mhi_trigger_reset;
+
+ mhi_pm_sys_err_handler(mhi_cntrl);
+ ret = 0;
+
+exit_mhi_trigger_reset:
+ mhi_device_put(mhi_dev, MHI_VOTE_DEVICE);
+
+ return ret;
+}
+
+static int mhi_debugfs_states_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_states_show, inode->i_private);
+}
+
+static int mhi_debugfs_events_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_events_show, inode->i_private);
+}
+
+static int mhi_debugfs_channels_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_channels_show, inode->i_private);
+}
+
+static int mhi_debugfs_votes_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_votes_show, inode->i_private);
+}
+
+static int mhi_debugfs_bus_vote_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_bus_vote_show, inode->i_private);
+}
+
+static int mhi_debugfs_device_vote_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_device_vote_show, inode->i_private);
+}
+
+static int mhi_debugfs_timeout_ms_open(struct inode *inode, struct file *fp)
+{
+ return single_open(fp, mhi_debugfs_timeout_ms_show, inode->i_private);
+}
+
+static const struct file_operations debugfs_states_fops = {
+ .open = mhi_debugfs_states_open,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_events_fops = {
+ .open = mhi_debugfs_events_open,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_channels_fops = {
+ .open = mhi_debugfs_channels_open,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_votes_fops = {
+ .open = mhi_debugfs_votes_open,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_bus_vote_fops = {
+ .open = mhi_debugfs_bus_vote_open,
+ .write = mhi_debugfs_bus_vote_write,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_device_vote_fops = {
+ .open = mhi_debugfs_device_vote_open,
+ .write = mhi_debugfs_device_vote_write,
+ .release = single_release,
+ .read = seq_read,
+};
+
+static const struct file_operations debugfs_timeout_ms_fops = {
+ .open = mhi_debugfs_timeout_ms_open,
+ .write = mhi_debugfs_timeout_ms_write,
+ .release = single_release,
+ .read = seq_read,
+};
+
+DEFINE_DEBUGFS_ATTRIBUTE(debugfs_reset_fops, NULL,
+ mhi_debugfs_trigger_reset, "%llu\n");
+
+static struct dentry *mhi_debugfs_root;
+
+void mhi_create_debugfs(struct mhi_controller *mhi_cntrl)
+{
+ if (IS_ERR_OR_NULL(mhi_debugfs_root))
+ return;
+
+ mhi_cntrl->debugfs_dentry =
+ debugfs_create_dir(dev_name(mhi_cntrl->cntrl_dev),
+ mhi_debugfs_root);
+ if (IS_ERR_OR_NULL(mhi_cntrl->debugfs_dentry))
+ return;
+
+ debugfs_create_file("states", 0444, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_states_fops);
+ debugfs_create_file("events", 0444, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_events_fops);
+ debugfs_create_file("channels", 0444, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_channels_fops);
+ debugfs_create_file("votes", 0444, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_votes_fops);
+ debugfs_create_file("bus_vote", 0644, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_bus_vote_fops);
+ debugfs_create_file("device_vote", 0644, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_device_vote_fops);
+ debugfs_create_file("timeout_ms", 0644, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_timeout_ms_fops);
+ debugfs_create_file("reset", 0444, mhi_cntrl->debugfs_dentry,
+ mhi_cntrl, &debugfs_reset_fops);
+}
+
+void mhi_destroy_debugfs(struct mhi_controller *mhi_cntrl)
+{
+ debugfs_remove_recursive(mhi_cntrl->debugfs_dentry);
+ mhi_cntrl->debugfs_dentry = NULL;
+}
+
+void mhi_debugfs_init(void)
+{
+ mhi_debugfs_root = debugfs_create_dir(mhi_bus_type.name, NULL);
+}
+
+void mhi_debugfs_exit(void)
+{
+ debugfs_remove_recursive(mhi_debugfs_root);
+}
diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index da94a04..17e3f7d 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -4,6 +4,7 @@
*
*/
+#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/dma-direction.h>
#include <linux/dma-mapping.h>
@@ -914,6 +915,8 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
mhi_cntrl->mhi_dev = mhi_dev;
+ mhi_create_debugfs(mhi_cntrl);
+
return 0;
error_add_dev:
@@ -936,6 +939,8 @@ void mhi_unregister_controller(struct mhi_controller *mhi_cntrl)
struct mhi_chan *mhi_chan = mhi_cntrl->mhi_chan;
unsigned int i;
+ mhi_destroy_debugfs(mhi_cntrl);
+
kfree(mhi_cntrl->mhi_cmd);
kfree(mhi_cntrl->mhi_event);
@@ -1285,11 +1290,13 @@ struct bus_type mhi_bus_type = {
static int __init mhi_init(void)
{
+ mhi_debugfs_init();
return bus_register(&mhi_bus_type);
}
static void __exit mhi_exit(void)
{
+ mhi_debugfs_exit();
bus_unregister(&mhi_bus_type);
}
diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index 2f18be7..798aa483 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -570,6 +570,30 @@ struct mhi_chan {
/* Default MHI timeout */
#define MHI_TIMEOUT_MS (1000)
+/* debugfs related functions */
+#ifdef CONFIG_MHI_BUS_DEBUG
+void mhi_create_debugfs(struct mhi_controller *mhi_cntrl);
+void mhi_destroy_debugfs(struct mhi_controller *mhi_cntrl);
+void mhi_debugfs_init(void);
+void mhi_debugfs_exit(void);
+#else
+static inline void mhi_create_debugfs(struct mhi_controller *mhi_cntrl)
+{
+}
+
+static inline void mhi_destroy_debugfs(struct mhi_controller *mhi_cntrl)
+{
+}
+
+static inline void mhi_debugfs_init(void)
+{
+}
+
+static inline void mhi_debugfs_exit(void)
+{
+}
+#endif
+
struct mhi_device *mhi_alloc_device(struct mhi_controller *mhi_cntrl);
int mhi_destroy_device(struct device *dev, void *data);
diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
index 0b68dcd..29d6cd7 100644
--- a/drivers/bus/mhi/core/pm.c
+++ b/drivers/bus/mhi/core/pm.c
@@ -256,6 +256,7 @@ int mhi_pm_m0_transition(struct mhi_controller *mhi_cntrl)
dev_err(dev, "Unable to transition to M0 state\n");
return -EIO;
}
+ mhi_cntrl->M0++;
/* Wake up the device */
read_lock_bh(&mhi_cntrl->pm_lock);
@@ -326,6 +327,8 @@ void mhi_pm_m1_transition(struct mhi_controller *mhi_cntrl)
mhi_cntrl->dev_state = MHI_STATE_M2;
write_unlock_irq(&mhi_cntrl->pm_lock);
+
+ mhi_cntrl->M2++;
wake_up_all(&mhi_cntrl->state_event);
/* If there are any pending resources, exit M2 immediately */
@@ -362,6 +365,7 @@ int mhi_pm_m3_transition(struct mhi_controller *mhi_cntrl)
return -EIO;
}
+ mhi_cntrl->M3++;
wake_up_all(&mhi_cntrl->state_event);
return 0;
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index 9b7bf28..026a624 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -291,6 +291,7 @@ struct mhi_controller_config {
* @cntrl_dev: Pointer to the struct device of physical bus acting as the MHI
* controller (required)
* @mhi_dev: MHI device instance for the controller
+ * @debugfs_dentry: MHI controller debugfs directory
* @regs: Base address of MHI MMIO register space (required)
* @bhi: Points to base of MHI BHI register space
* @bhie: Points to base of MHI BHIe register space
@@ -329,6 +330,7 @@ struct mhi_controller_config {
* @dev_state: MHI device state
* @dev_wake: Device wakeup count
* @pending_pkts: Pending packets for the controller
+ * @M0, M2, M3, M3_fast: Counters to track number of device MHI state changes
* @transition_list: List of MHI state transitions
* @transition_lock: Lock for protecting MHI state transition list
* @wlock: Lock for protecting device wakeup
@@ -367,6 +369,7 @@ struct mhi_controller_config {
struct mhi_controller {
struct device *cntrl_dev;
struct mhi_device *mhi_dev;
+ struct dentry *debugfs_dentry;
void __iomem *regs;
void __iomem *bhi;
void __iomem *bhie;
@@ -408,6 +411,7 @@ struct mhi_controller {
enum mhi_state dev_state;
atomic_t dev_wake;
atomic_t pending_pkts;
+ u32 M0, M2, M3, M3_fast;
struct list_head transition_list;
spinlock_t transition_lock;
spinlock_t wlock;
--
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