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Subject[PATCHv4 09/11] xshm: Character device for XSHM channel access.
Date
This patch introduces a character interface to the XSHM channels.
A misc device is created, providing asynchronous IO and management.

The character device implements ring-buffer handling, copying
data directly from the Shared Memory area into user buffers.

Signed-off-by: Sjur Brændeland <sjur.brandeland@stericsson.com>
---
drivers/xshm/xshm_chr.c | 1262 +++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1262 insertions(+), 0 deletions(-)
create mode 100644 drivers/xshm/xshm_chr.c
diff --git a/drivers/xshm/xshm_chr.c b/drivers/xshm/xshm_chr.c
new file mode 100644
index 0000000..6951a90
--- /dev/null
+++ b/drivers/xshm/xshm_chr.c
@@ -0,0 +1,1262 @@
+/*
+ * Copyright (C) ST-Ericsson AB 2011
+ * Author: Per Sigmond / Per.Sigmond@stericsson.com
+ * Sjur Brændeland / sjur.brandeland@stericsson.com
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s :" fmt, __func__
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/wait.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/uaccess.h>
+#include <asm/uaccess.h>
+#include <asm/atomic.h>
+#include <linux/xshm/xshm_dev.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Sjur Brændland <sjur.brandeland@stericsson.com>");
+
+static LIST_HEAD(xshmchr_chrdev_list);
+static spinlock_t list_lock;
+
+#define xdev_dbg(dev, fmt, arg...) \
+ dev_dbg(dev->misc.this_device, pr_fmt(fmt), ##arg)
+
+#define xdev_vdbg(dev, fmt, arg...) \
+ dev_vdbg(dev->misc.this_device, pr_fmt(fmt), ##arg)
+
+#define pr_xchrstate(dev, str, arg...) \
+ xdev_vdbg(dev, str " State: %s %s\n", ##arg, \
+ STATE_IS_PENDING(dev) ? "pending" : "", \
+ STATE_IS_OPEN(dev) ? "open" : "close")
+
+#define OPEN_TOUT (25 * HZ)
+#define CONN_STATE_OPEN_BIT 0
+#define CONN_STATE_PENDING_BIT 1
+#define CONN_REMOTE_TEARDOWN_BIT 2
+#define CONN_EOF_BIT 4
+
+#define STATE_IS_OPEN(dev) test_bit(CONN_STATE_OPEN_BIT, \
+ (void *) &(dev)->conn_state)
+#define STATE_IS_REMOTE_TEARDOWN(dev) test_bit(CONN_REMOTE_TEARDOWN_BIT, \
+ (void *) &(dev)->conn_state)
+#define STATE_IS_PENDING(dev) test_bit(CONN_STATE_PENDING_BIT, \
+ (void *) &(dev)->conn_state)
+#define SET_STATE_OPEN(dev) (set_bit(CONN_STATE_OPEN_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_STATE_OPEN:%d\n", dev->conn_state))
+#define SET_STATE_CLOSED(dev) (clear_bit(CONN_STATE_OPEN_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_STATE_CLOSED:%d\n", dev->conn_state))
+#define SET_PENDING_ON(dev) (set_bit(CONN_STATE_PENDING_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_PENDING_ON:%d\n", dev->conn_state))
+#define SET_PENDING_OFF(dev) (clear_bit(CONN_STATE_PENDING_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_PENDING_OFF:%d\n", dev->conn_state))
+#define SET_REMOTE_TEARDOWN(dev) (set_bit(CONN_REMOTE_TEARDOWN_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_REMOTE_TEARDOWN:%d\n", dev->conn_state))
+#define CLEAR_REMOTE_TEARDOWN(dev) (clear_bit(CONN_REMOTE_TEARDOWN_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("CLEAR_REMOTE_TEARDOWN:%d\n", dev->conn_state))
+#define SET_EOF(dev) (set_bit(CONN_EOF_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("SET_EOF:%d\n", dev->conn_state))
+#define CLEAR_EOF(dev) (clear_bit(CONN_EOF_BIT, \
+ (void *) &(dev)->conn_state), \
+ pr_devel("CLEAR_EOF:%d\n", dev->conn_state))
+#define STATE_IS_EOF(dev) test_bit(CONN_EOF_BIT, \
+ (void *) &(dev)->conn_state)
+
+#define CHR_READ_FLAG 0x01
+#define CHR_WRITE_FLAG 0x02
+
+#ifdef CONFIG_DEBUG_FS
+static struct dentry *debugfsdir;
+#include <linux/debugfs.h>
+#define dbfs_atomic_inc(a) atomic_inc(a)
+#define dbfs_atomic_add(v, a) atomic_add_return(v, a)
+#else
+#define dbfs_atomic_inc(a) 0
+#define dbfs_atomic_add(v, a) 0
+#endif
+
+struct ringbuf {
+ __le32 *ri; /* Pointer to read-index in shared memory.*/
+ __le32 *wi; /* Pointer to write-index in shared memory */
+ unsigned int size;/* Size of buffer */
+ void *data; /* Buffer data in shared memory */
+};
+
+struct xshmchr_char_dev {
+ struct xshm_dev *xshm;
+ struct kref kref;
+ struct ringbuf rx, tx;
+ u32 conn_state;
+ char name[256];
+ struct miscdevice misc;
+ int file_mode;
+
+ /* Access to this struct and below layers */
+ struct mutex mutex;
+ wait_queue_head_t mgmt_wq;
+ /* List of misc test devices */
+ struct list_head list_field;
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *debugfs_device_dir;
+ atomic_t num_open;
+ atomic_t num_close;
+ atomic_t num_read;
+ atomic_t num_read_block;
+ atomic_t num_read_bytes;
+
+ atomic_t num_write;
+ atomic_t num_write_block;
+ atomic_t num_write_bytes;
+
+ atomic_t num_init;
+ atomic_t num_init_resp;
+ atomic_t num_deinit;
+ atomic_t num_deinit_resp;
+ atomic_t num_remote_teardown_ind;
+
+#endif
+};
+
+static void xshm_release(struct kref *kref)
+{
+ struct xshmchr_char_dev *dev;
+ dev = container_of(kref, struct xshmchr_char_dev, kref);
+ xdev_vdbg(dev, "Freeing device\n");
+ kfree(dev);
+}
+
+static void xshmchr_get(struct xshmchr_char_dev *dev)
+{
+ kref_get(&dev->kref);
+}
+
+static void xshmchr_put(struct xshmchr_char_dev *dev)
+{
+ kref_put(&dev->kref, xshm_release);
+}
+
+static inline unsigned int ringbuf_empty(struct ringbuf *rb)
+{
+ return *rb->wi == *rb->ri;
+}
+
+static inline unsigned int ringbuf_full(struct ringbuf *rb)
+{
+ return (le32_to_cpu(*rb->wi) + 1) % rb->size == le32_to_cpu(*rb->ri);
+}
+
+static int insert_ringbuf(struct ringbuf *rb, const char __user *from,
+ u32 len)
+{
+ u32 wi = le32_to_cpu(*rb->wi);
+ u32 ri = le32_to_cpu(*rb->ri);
+ u32 cpylen, cpylen2 = 0, notcpy;
+
+ pr_devel("insert: wi:%d ri:%d len:%d\n", wi, ri, len);
+ if (wi >= ri) {
+ len = min(len, rb->size - 1 - wi + ri);
+ cpylen = min(rb->size, wi + len) - wi;
+
+ /* Write is ahead of read, copy 'cpylen' data from 'wi' */
+ notcpy = copy_from_user(rb->data + wi, from, cpylen);
+ if (cpylen > 0 && notcpy == cpylen)
+ return -EIO;
+
+ if (cpylen < len && notcpy == 0) {
+ cpylen2 = min(ri - 1 , len - cpylen);
+
+ /* We have wrapped copy 'cpylen2' from start */
+ notcpy = copy_from_user(rb->data, from + cpylen,
+ cpylen2);
+ }
+ } else {
+ cpylen = min(ri - 1 - wi , len);
+
+ /* Read is ahead of write, copy from wi to (ri - 1) */
+ notcpy = copy_from_user(rb->data + wi, from, cpylen);
+ if (cpylen > 0 && notcpy == cpylen)
+ return -EIO;
+
+ }
+ /* Do write barrier before updating index */
+ smp_wmb();
+ *rb->wi = cpu_to_le32((wi + cpylen + cpylen2 - notcpy) % rb->size);
+ pr_devel("write ringbuf: wi: %d->%d l:%d\n",
+ wi, le32_to_cpu(*rb->wi), cpylen + cpylen2);
+ return cpylen + cpylen2 - notcpy;
+}
+
+static int extract_ringbuf(struct ringbuf *rb, void __user *to, u32 len)
+{
+ u32 wi = le32_to_cpu(*rb->wi);
+ u32 ri = le32_to_cpu(*rb->ri);
+ u32 cpylen = 0, cpylen2 = 0, notcpy;
+
+ pr_devel("extract: wi:%d ri:%d len:%d\n", wi, ri, len);
+ if (ri <= wi) {
+ len = min(wi - ri, len);
+
+ /* Read is ahead of write, copy 'len' data from 'ri' */
+ notcpy = copy_to_user(to, rb->data + ri, len);
+ if (len > 0 && notcpy == len)
+ return -EIO;
+
+ /* Do write barrier before updating index */
+ smp_wmb();
+ *rb->ri = cpu_to_le32(ri + len - notcpy);
+ pr_devel("read ringbuf: ri: %d->%d len:%d\n",
+ ri, le32_to_cpu(*rb->ri), len - notcpy);
+
+ return len - notcpy;
+ } else {
+ /* wr >= ri */
+ cpylen = min(rb->size - ri, len);
+
+ /* Write is ahead, copy 'cpylen' data from ri until end */
+ notcpy = copy_to_user(to, rb->data + ri, cpylen);
+ if (cpylen > 0 && notcpy == cpylen)
+ return -EIO;
+ if (cpylen < len && notcpy == 0) {
+ cpylen2 = min(wi , len - cpylen);
+ /* we have wrapped copy from [0 .. cpylen2] */
+ notcpy = copy_to_user(to + cpylen, rb->data, cpylen2);
+ }
+ /* Do write barrier before updating index */
+ smp_wmb();
+
+ *rb->ri = cpu_to_le32((ri + cpylen + cpylen2 - notcpy)
+ % rb->size);
+ pr_devel("read ringbuf: ri: %d->%d cpylen:%d\n",
+ ri, le32_to_cpu(*rb->ri), cpylen + cpylen2 - notcpy);
+
+ return cpylen + cpylen2 - notcpy;
+ }
+}
+
+static void drain_ringbuf(struct xshmchr_char_dev *dev)
+{
+ /* Empty the ringbuf. */
+ *dev->xshm->cfg.rx.read = *dev->xshm->cfg.rx.write;
+ *dev->xshm->cfg.tx.write = *dev->xshm->cfg.tx.read;
+}
+
+static int open_cb(void *drv)
+{
+ struct xshmchr_char_dev *dev = drv;
+
+ pr_xchrstate(dev, "enter");
+ dbfs_atomic_inc(&dev->num_init_resp);
+ /* Signal reader that data is available. */
+ WARN_ON(!STATE_IS_OPEN(dev));
+ SET_PENDING_OFF(dev);
+ wake_up_interruptible_all(&dev->mgmt_wq);
+ pr_xchrstate(dev, "exit");
+ return 0;
+}
+
+static void close_cb(void *drv)
+{
+ struct xshmchr_char_dev *dev = drv;
+
+ pr_xchrstate(dev, "enter");
+ dbfs_atomic_inc(&dev->num_remote_teardown_ind);
+ if (STATE_IS_PENDING(dev) && !STATE_IS_OPEN(dev)) {
+ /* Normal close sequence */
+ SET_PENDING_OFF(dev);
+ CLEAR_REMOTE_TEARDOWN(dev);
+ SET_EOF(dev);
+ drain_ringbuf(dev);
+ dev->file_mode = 0;
+ } else {
+ /* Remote teardown, close should be called from user-space */
+ SET_REMOTE_TEARDOWN(dev);
+ SET_PENDING_OFF(dev);
+ }
+
+ wake_up_interruptible_all(&dev->mgmt_wq);
+ pr_xchrstate(dev, "exit");
+}
+
+static int ipc_rx_cb(void *drv)
+{
+ struct xshmchr_char_dev *dev = drv;
+
+ xdev_vdbg(dev, "enter\n");
+
+ if (unlikely(*dev->xshm->cfg.rx.state == cpu_to_le32(XSHM_CLOSED)))
+ return -ESHUTDOWN;
+
+ /*
+ * Performance could perhaps be improved by having a WAIT
+ * flag, similar to SOCK_ASYNC_WAITDATA, and only do wake up
+ * when it's actually needed.
+ */
+ wake_up_interruptible_all(&dev->mgmt_wq);
+ return 0;
+}
+
+static int ipc_tx_release_cb(void *drv)
+{
+ struct xshmchr_char_dev *dev = drv;
+
+ xdev_vdbg(dev, "enter\n");
+ wake_up_interruptible_all(&dev->mgmt_wq);
+ return 0;
+}
+
+/* Device Read function called from Linux kernel */
+static ssize_t xshmchr_chrread(struct file *filp, char __user *buf,
+ size_t count, loff_t *f_pos)
+{
+ unsigned int len = 0;
+ int result;
+ struct xshmchr_char_dev *dev = filp->private_data;
+ ssize_t ret = -EIO;
+
+ if (dev == NULL) {
+ xdev_dbg(dev, "private_data not set!\n");
+ return -EBADFD;
+ }
+
+ /* I want to be alone on dev (except status and queue) */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ return -ERESTARTSYS;
+ }
+ xshmchr_get(dev);
+
+ if (!STATE_IS_OPEN(dev)) {
+ /* Device is closed or closing. */
+ if (!STATE_IS_PENDING(dev)) {
+ xdev_dbg(dev, "device is closed (by remote)\n");
+ ret = -ECONNRESET;
+ } else {
+ xdev_dbg(dev, "device is closing...\n");
+ ret = -EBADF;
+ }
+ goto read_error;
+ }
+
+ dbfs_atomic_inc(&dev->num_read);
+
+ /* Device is open or opening. */
+ if (STATE_IS_PENDING(dev)) {
+ xdev_vdbg(dev, "device is opening...\n");
+
+ dbfs_atomic_inc(&dev->num_read_block);
+ if (filp->f_flags & O_NONBLOCK) {
+ /* We can't block. */
+ xdev_dbg(dev, "exit: state pending and O_NONBLOCK\n");
+ ret = -EAGAIN;
+ goto read_error;
+ }
+
+ /*
+ * To reach here client must do blocking open,
+ * and start read() before open completes. This is
+ * quite quirky, but let's handle it anyway.
+ */
+ result =
+ wait_event_interruptible(dev->mgmt_wq,
+ !STATE_IS_PENDING(dev) ||
+ STATE_IS_REMOTE_TEARDOWN(dev));
+
+ if (result == -ERESTARTSYS) {
+ xdev_dbg(dev, "wait_event_interruptible"
+ " woken by a signal (1)\n");
+ ret = -ERESTARTSYS;
+ goto read_error;
+ }
+ if (STATE_IS_REMOTE_TEARDOWN(dev)) {
+ xdev_dbg(dev,
+ "received remote_shutdown indication (1)\n");
+ ret = -ESHUTDOWN;
+ goto read_error;
+ }
+ }
+
+ /* Block if we don't have any received buffers.
+ * The queue has its own lock.
+ */
+ while (ringbuf_empty(&dev->rx)) {
+
+ if (filp->f_flags & O_NONBLOCK) {
+ xdev_vdbg(dev, "exit: O_NONBLOCK\n");
+ ret = -EAGAIN;
+ goto read_error;
+ }
+
+ /* Let writers in. */
+ mutex_unlock(&dev->mutex);
+
+ xdev_vdbg(dev, "wait for data\n");
+ /* Block reader until data arrives or device is closed. */
+ if (wait_event_interruptible(dev->mgmt_wq,
+ !ringbuf_empty(&dev->rx)
+ || STATE_IS_REMOTE_TEARDOWN(dev)
+ || !STATE_IS_OPEN(dev)) == -ERESTARTSYS) {
+ xdev_vdbg(dev, "event_interruptible woken by "
+ "a signal, signal_pending(current) = %d\n",
+ signal_pending(current));
+ return -ERESTARTSYS;
+ }
+
+ xdev_vdbg(dev, "wakeup readq\n");
+
+ if (STATE_IS_REMOTE_TEARDOWN(dev) && ringbuf_empty(&dev->rx)) {
+ if (!STATE_IS_EOF(dev)) {
+ xdev_dbg(dev, "First EOF OK\n");
+ SET_EOF(dev);
+ ret = 0;
+ goto error_nolock;
+ }
+ xdev_dbg(dev, "2'nd EOF - remote_shutdown\n");
+ ret = -ECONNRESET;
+ goto error_nolock;
+ }
+
+ /* I want to be alone on dev (except status and queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible"
+ " got signalled\n");
+ return -ERESTARTSYS;
+ }
+
+ if (!STATE_IS_OPEN(dev)) {
+ /* Someone closed the link, report error. */
+ xdev_dbg(dev, "remote end shutdown!\n");
+ ret = -EBADF;
+ goto read_error;
+ }
+ }
+
+ xdev_vdbg(dev, "copy data\n");
+ len = extract_ringbuf(&dev->rx, buf, count);
+ if (len <= 0) {
+ xdev_dbg(dev, "Extracting from ringbuf failed\n");
+ ret = -EINVAL;
+ goto read_error;
+ }
+
+ /* Signal to modem that data is read from ringbuf */
+
+ dev->xshm->ipc_rx_release(dev->xshm, false);
+
+ dbfs_atomic_add(len, &dev->num_read_bytes);
+ /* Let the others in. */
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return len;
+
+read_error:
+ mutex_unlock(&dev->mutex);
+error_nolock:
+ xshmchr_put(dev);
+ return ret;
+}
+
+/* Device write function called from Linux kernel (misc device) */
+static ssize_t xshmchr_chrwrite(struct file *filp, const char __user *buf,
+ size_t count, loff_t *f_pos)
+{
+ struct xshmchr_char_dev *dev = filp->private_data;
+ ssize_t ret = -EIO;
+ int result;
+ uint len = 0;
+
+ if (dev == NULL) {
+ xdev_dbg(dev, "private_data not set!\n");
+ ret = -EBADFD;
+ goto write_error_no_unlock;
+ }
+
+ pr_xchrstate(dev, "enter");
+
+ /* I want to be alone on dev (except status and queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ ret = -ERESTARTSYS;
+ goto write_error_no_unlock;
+ }
+ xshmchr_get(dev);
+
+ dbfs_atomic_inc(&dev->num_write);
+ if (!STATE_IS_OPEN(dev)) {
+ /* Device is closed or closing. */
+ if (!STATE_IS_PENDING(dev)) {
+ xdev_dbg(dev, "device is closed (by remote)\n");
+ ret = -EPIPE;
+ } else {
+ xdev_dbg(dev, "device is closing...\n");
+ ret = -EBADF;
+ }
+ goto write_error;
+ }
+
+ /* Device is open or opening. */
+ if (STATE_IS_PENDING(dev)) {
+ xdev_dbg(dev, "device is opening...\n");
+
+ dbfs_atomic_inc(&dev->num_write_block);
+ if (filp->f_flags & O_NONBLOCK) {
+ /* We can't block */
+ xdev_dbg(dev, "exit: state pending and O_NONBLOCK\n");
+ ret = -EAGAIN;
+ goto write_error;
+ }
+
+ /* Blocking mode; state is pending and we need to wait
+ * for its conclusion. (Shutdown_ind set pending off.)
+ */
+ result =
+ wait_event_interruptible(dev->mgmt_wq,
+ !STATE_IS_PENDING(dev) ||
+ STATE_IS_REMOTE_TEARDOWN(dev));
+ if (result == -ERESTARTSYS) {
+ xdev_dbg(dev, "wait_event_interruptible"
+ " woken by a signal (1)\n");
+ ret = -ERESTARTSYS;
+ goto write_error;
+ }
+ }
+ if (STATE_IS_REMOTE_TEARDOWN(dev)) {
+ xdev_dbg(dev, "received remote_shutdown indication\n");
+ ret = -EPIPE;
+ goto write_error;
+ }
+
+ while (ringbuf_full(&dev->tx)) {
+ /* Flow is off. Check non-block flag. */
+ if (filp->f_flags & O_NONBLOCK) {
+ xdev_dbg(dev, "exit: O_NONBLOCK and tx flow off");
+ ret = -EAGAIN;
+ goto write_error;
+ }
+
+ /* Let readers in. */
+ mutex_unlock(&dev->mutex);
+
+ xdev_vdbg(dev, "wait for write space\n");
+ /* Wait until flow is on or device is closed. */
+ if (wait_event_interruptible(dev->mgmt_wq,
+ !ringbuf_full(&dev->tx)
+ || !STATE_IS_OPEN(dev)
+ || STATE_IS_REMOTE_TEARDOWN(dev)
+ ) == -ERESTARTSYS) {
+ xdev_dbg(dev, "wait_event_interruptible"
+ " woken by a signal (1)\n");
+ ret = -ERESTARTSYS;
+ goto write_error_no_unlock;
+ }
+
+ /* I want to be alone on dev (except status and queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible "
+ "got signalled\n");
+ ret = -ERESTARTSYS;
+ goto write_error_no_unlock;
+ }
+
+ xdev_vdbg(dev, "wakeup got write space\n");
+ if (!STATE_IS_OPEN(dev)) {
+ /* Someone closed the link, report error. */
+ xdev_dbg(dev, "remote end shutdown!\n");
+ ret = -EPIPE;
+ goto write_error;
+ }
+ if (STATE_IS_REMOTE_TEARDOWN(dev)) {
+ xdev_dbg(dev, "received remote_shutdown indication\n");
+ ret = -ESHUTDOWN;
+ goto write_error;
+ }
+ }
+ len = insert_ringbuf(&dev->tx, buf, count);
+ xdev_vdbg(dev, "inserted %d bytes\n", len);
+ if (len <= 0) {
+ xdev_dbg(dev, "transmit failed, error = %d\n",
+ (int) ret);
+ goto write_error;
+ }
+
+ dbfs_atomic_add(len, &dev->num_write_bytes);
+
+ /* Signal to modem that data is put in ringbuf */
+ dev->xshm->ipc_tx(dev->xshm);
+
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return len;
+
+write_error:
+ mutex_unlock(&dev->mutex);
+write_error_no_unlock:
+ xshmchr_put(dev);
+ return ret;
+}
+
+static unsigned int xshmchr_chrpoll(struct file *filp, poll_table *waittab)
+{
+ struct xshmchr_char_dev *dev = filp->private_data;
+ unsigned int mask = 0;
+
+ if (dev == NULL) {
+ xdev_dbg(dev, "private_data not set!\n");
+ return -EBADFD;
+ }
+
+ /* I want to be alone on dev (except status and queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ mask |= POLLERR;
+ goto out_unlocked;
+ }
+ xshmchr_get(dev);
+
+ if (STATE_IS_REMOTE_TEARDOWN(dev)) {
+ xdev_dbg(dev, "not open\n");
+ mask |= POLLRDHUP | POLLHUP;
+ goto out;
+ }
+
+ xdev_vdbg(dev, "poll wait\n");
+ poll_wait(filp, &dev->mgmt_wq, waittab);
+
+ if (STATE_IS_OPEN(dev) && STATE_IS_PENDING(dev))
+ goto out;
+
+ if (!ringbuf_empty(&dev->rx))
+ mask |= (POLLIN | POLLRDNORM);
+
+ if (!ringbuf_full(&dev->tx))
+ mask |= (POLLOUT | POLLWRNORM);
+
+out:
+ mutex_unlock(&dev->mutex);
+out_unlocked:
+ xdev_vdbg(dev, "poll return mask=0x%04x\n", mask);
+ xshmchr_put(dev);
+ return mask;
+}
+
+/* Usage:
+ * minor >= 0 : find from minor
+ * minor < 0 and name == name : find from name
+ * minor < 0 and name == NULL : get first
+ */
+
+static struct xshmchr_char_dev *find_device(int minor, char *name,
+ int remove_from_list)
+{
+ struct list_head *list_node;
+ struct list_head *n;
+ struct xshmchr_char_dev *dev = NULL;
+ struct xshmchr_char_dev *tmp;
+ spin_lock(&list_lock);
+ pr_devel("start looping\n");
+ list_for_each_safe(list_node, n, &xshmchr_chrdev_list) {
+ tmp = list_entry(list_node, struct xshmchr_char_dev,
+ list_field);
+ if (minor >= 0) { /* find from minor */
+ if (tmp->misc.minor == minor)
+ dev = tmp;
+
+ } else if (name) { /* find from name */
+ if (!strncmp(tmp->name, name, sizeof(tmp->name)))
+ dev = tmp;
+ } else { /* take first */
+ dev = tmp;
+ }
+
+ if (dev) {
+ xdev_vdbg(dev, "match %d, %s\n",
+ minor, name);
+ if (remove_from_list)
+ list_del(list_node);
+ break;
+ }
+ }
+ spin_unlock(&list_lock);
+ return dev;
+}
+
+static int xshmchr_chropen(struct inode *inode, struct file *filp)
+{
+ struct xshmchr_char_dev *dev = NULL;
+ int result = -1;
+ int minor = iminor(inode);
+ int mode = 0;
+ int ret = -EIO;
+
+ dev = find_device(minor, NULL, 0);
+ pr_xchrstate(dev, "enter");
+
+ if (dev == NULL) {
+ xdev_dbg(dev, "Could not find device\n");
+ return -EBADF;
+ }
+
+ /* I want to be alone on dev (except status and queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ return -ERESTARTSYS;
+ }
+
+ xshmchr_get(dev);
+ dbfs_atomic_inc(&dev->num_open);
+ filp->private_data = dev;
+
+ switch (filp->f_flags & O_ACCMODE) {
+ case O_RDONLY:
+ mode = CHR_READ_FLAG;
+ break;
+ case O_WRONLY:
+ mode = CHR_WRITE_FLAG;
+ break;
+ case O_RDWR:
+ mode = CHR_READ_FLAG | CHR_WRITE_FLAG;
+ break;
+ }
+
+ /* If device is not open, make sure device is in fully closed state. */
+ if (!STATE_IS_OPEN(dev)) {
+ /* Has link close response been received
+ * (if we ever sent it)?
+ */
+ if (STATE_IS_PENDING(dev)) {
+ /* Still waiting for close response from remote.
+ * If opened non-blocking, report "would block".
+ */
+ if (filp->f_flags & O_NONBLOCK) {
+ xdev_vdbg(dev,
+ "exit: O_NONBLOCK && close pending\n");
+ ret = -EAGAIN;
+ goto open_error;
+ }
+
+ xdev_vdbg(dev, "WAIT for close response from remote\n");
+
+ /*
+ * Blocking mode; close is pending and we need to wait
+ * for its conclusion. However modem may be dead,
+ * or resureccted and alive waiting for
+ * an open ack.
+ * It's hard to get this rigth - if state is
+ * pending. We have missed a state update,
+ * let's just wait for ack, and then proceede
+ * with watever state we have.
+ */
+ result =
+ wait_event_interruptible_timeout(dev->mgmt_wq,
+ !STATE_IS_PENDING(dev) ||
+ STATE_IS_REMOTE_TEARDOWN(dev),
+ OPEN_TOUT);
+
+ if (result == -ERESTARTSYS) {
+ xdev_dbg(dev, "wait_event_interruptible"
+ " woken by a signal (1)\n");
+ ret = -ERESTARTSYS;
+ goto open_error;
+ }
+
+ if (result == 0) {
+ SET_PENDING_OFF(dev);
+ pr_xchrstate(dev,
+ "Timeout -pending close -Clear pending");
+ } else
+ pr_xchrstate(dev, "wakeup (wait for close)");
+ }
+ }
+
+ /* Device is now either closed, pending open or open */
+ if (STATE_IS_OPEN(dev) && !STATE_IS_PENDING(dev)) {
+ /* Open */
+ xdev_vdbg(dev, "Device is already opened (dev=%p) check"
+ "access f_flags = 0x%x file_mode = 0x%x\n",
+ dev, mode, dev->file_mode);
+
+ if (mode & dev->file_mode) {
+ xdev_vdbg(dev, "Access mode already in use 0x%x\n",
+ mode);
+ ret = -EBUSY;
+ goto open_error;
+ }
+ } else {
+
+ /* We are closed or pending open.
+ * If closed: send link setup
+ * If pending open: link setup already sent (we could have been
+ * interrupted by a signal last time)
+ */
+ if (!STATE_IS_OPEN(dev)) {
+ /* First opening of file; do connect */
+
+ SET_STATE_OPEN(dev);
+ SET_PENDING_ON(dev);
+ CLEAR_EOF(dev);
+ /* Send "open" by resetting indexes */
+ result = dev->xshm->open(dev->xshm);
+
+ if (result < 0) {
+ xdev_dbg(dev, "can't open channel\n");
+ ret = -EIO;
+ SET_STATE_CLOSED(dev);
+ SET_PENDING_OFF(dev);
+ goto open_error;
+ }
+ dbfs_atomic_inc(&dev->num_init);
+ }
+
+ /* If opened non-blocking, report "success".
+ */
+ if (filp->f_flags & O_NONBLOCK) {
+ xdev_vdbg(dev, "EXIT: O_NONBLOCK success\n");
+ ret = 0;
+ goto open_success;
+ }
+
+ xdev_vdbg(dev, "WAIT for connect response\n");
+ /*
+ * misc_open holds a global mutex anyway so there is no
+ * reason to release our own while waiting
+ */
+ result =
+ wait_event_interruptible_timeout(dev->mgmt_wq,
+ !STATE_IS_PENDING(dev) ||
+ STATE_IS_REMOTE_TEARDOWN(dev),
+ OPEN_TOUT);
+ if (result == 0) {
+ xdev_dbg(dev, "wait_event_interruptible timeout (1)\n");
+ ret = -ETIMEDOUT;
+ goto open_error;
+ }
+ if (result == -ERESTARTSYS) {
+ xdev_dbg(dev, "wait_event_interruptible woken by sig");
+ ret = -ERESTARTSYS;
+ goto open_error;
+ }
+ if (STATE_IS_REMOTE_TEARDOWN(dev)) {
+ xdev_dbg(dev, "received remote_shutdown indication\n");
+ ret = -ESHUTDOWN;
+ goto open_error;
+ }
+
+ pr_xchrstate(dev, "wakeup (wait for open)");
+ if (!STATE_IS_OPEN(dev)) {
+ /* Lower layers said "no". */
+ xdev_dbg(dev, "xshmchr_chropen: Closed received\n");
+ ret = -EPIPE;
+ goto open_error;
+ }
+
+ xdev_vdbg(dev, "connect received\n");
+ }
+open_success:
+ /* Open is OK. */
+ dev->file_mode |= mode;
+
+ xdev_vdbg(dev, "file mode = %x\n", dev->file_mode);
+ pr_xchrstate(dev, "exit");
+
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return 0;
+
+open_error:
+ dev->xshm->close(dev->xshm);
+ SET_STATE_CLOSED(dev);
+ SET_PENDING_OFF(dev);
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return ret;
+}
+
+static int xshmchr_chrrelease(struct inode *inode, struct file *filp)
+{
+ struct xshmchr_char_dev *dev = NULL;
+ int minor = iminor(inode);
+ int mode = 0;
+
+
+ dev = find_device(minor, NULL, 0);
+ if (dev == NULL) {
+ xdev_dbg(dev, "Could not find device\n");
+ return -EBADF;
+ }
+
+ pr_xchrstate(dev, "enter");
+
+ /* I want to be alone on dev (except status queue). */
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ return -ERESTARTSYS;
+ }
+
+ xshmchr_get(dev);
+ dbfs_atomic_inc(&dev->num_close);
+
+ /* Is the device open? */
+ if (!STATE_IS_OPEN(dev)) {
+ xdev_vdbg(dev, "Device not open (dev=%p)\n",
+ dev);
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return 0;
+ }
+
+ switch (filp->f_flags & O_ACCMODE) {
+ case O_RDONLY:
+ mode = CHR_READ_FLAG;
+ break;
+ case O_WRONLY:
+ mode = CHR_WRITE_FLAG;
+ break;
+ case O_RDWR:
+ mode = CHR_READ_FLAG | CHR_WRITE_FLAG;
+ break;
+ }
+
+ dev->file_mode &= ~mode;
+ if (dev->file_mode) {
+ xdev_vdbg(dev, "Device is kept open by someone else, "
+ " don't close. XSHMCHR connection - file_mode = %x\n",
+ dev->file_mode);
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return 0;
+ }
+
+ /* IS_CLOSED have double meaning:
+ * 1) Spontanous Remote Shutdown Request.
+ * 2) Ack on a channel teardown(disconnect)
+ * Must clear bit, in case we previously received
+ * a remote shudown request.
+ */
+
+ SET_STATE_CLOSED(dev);
+ SET_PENDING_ON(dev);
+ CLEAR_REMOTE_TEARDOWN(dev);
+ SET_EOF(dev);
+
+ dev->xshm->close(dev->xshm);
+
+ dbfs_atomic_inc(&dev->num_deinit);
+
+ /* Empty the ringbuf */
+ drain_ringbuf(dev);
+ dev->file_mode = 0;
+
+ mutex_unlock(&dev->mutex);
+ pr_xchrstate(dev, "exit");
+ xshmchr_put(dev);
+ return 0;
+}
+
+static const struct file_operations xshmchr_chrfops = {
+ .owner = THIS_MODULE,
+ .read = xshmchr_chrread,
+ .write = xshmchr_chrwrite,
+ .open = xshmchr_chropen,
+ .release = xshmchr_chrrelease,
+ .poll = xshmchr_chrpoll,
+};
+
+static int cfshm_probe(struct xshm_dev *xshm)
+
+{
+ struct xshmchr_char_dev *dev = NULL;
+ int result;
+
+ pr_devel("cfshm_probe called\n");
+ if (xshm == NULL)
+ return 0;
+
+ /* Allocate device */
+ dev = kmalloc(sizeof(*dev), GFP_KERNEL);
+
+ if (!dev) {
+ pr_err("kmalloc failed.\n");
+ return -ENOMEM;
+ }
+
+ memset(dev, 0, sizeof(*dev));
+ kref_init(&dev->kref);
+
+ dev->xshm = xshm;
+ mutex_init(&dev->mutex);
+ init_waitqueue_head(&dev->mgmt_wq);
+
+ /* Fill in some information concerning the misc device. */
+ dev->misc.minor = MISC_DYNAMIC_MINOR;
+ if (strlen(xshm->cfg.name) == 0) {
+ xdev_dbg(dev, "XSHM device does not have a name\n");
+ return -EINVAL;
+ }
+ sprintf(dev->name, "%s", xshm->cfg.name);
+ dev->misc.name = dev->name;
+ dev->misc.fops = &xshmchr_chrfops;
+
+ dev->tx.ri = xshm->cfg.tx.read;
+ dev->tx.wi = xshm->cfg.tx.write;
+ dev->tx.data = xshm->cfg.tx.addr;
+ dev->tx.size = xshm->cfg.tx.ch_size - 1;
+
+ dev->rx.ri = xshm->cfg.rx.read;
+ dev->rx.wi = xshm->cfg.rx.write;
+ dev->rx.data = xshm->cfg.rx.addr;
+ dev->rx.size = xshm->cfg.rx.ch_size - 1;
+ if (dev->rx.size < 2 || dev->tx.size < 2) {
+ dev->rx.size = 0;
+ dev->tx.size = 0;
+ xdev_dbg(dev, "dev:error - channel size too small\n");
+ return -EINVAL;
+ }
+ dev->xshm->ipc_rx_cb = ipc_rx_cb;
+ dev->xshm->ipc_tx_release_cb = ipc_tx_release_cb;
+ dev->xshm->open_cb = open_cb;
+ dev->xshm->close_cb = close_cb;
+ dev->xshm->driver_data = dev;
+
+ mutex_lock(&dev->mutex);
+
+ /* Register the device. */
+ dev->misc.parent = &xshm->dev;
+ pr_devel("register dev:%s chr=%s(%s) dev=%p\n",
+ dev_name(&dev->xshm->dev),
+ dev->name, xshm->cfg.name, dev);
+ result = misc_register(&dev->misc);
+
+ /* Lock in order to try to stop someone from opening the device
+ * too early. The misc device has its own lock. We cannot take our
+ * lock until misc_register() is finished, because in open() the
+ * locks are taken in this order (misc first and then dev).
+ * So anyone managing to open the device between the misc_register
+ * and the mutex_lock will get a "device not found" error. Don't
+ * think it can be avoided.
+ */
+
+ if (result < 0) {
+ pr_warn("error - %d, can't register misc\n",
+ result);
+ mutex_unlock(&dev->mutex);
+ goto err_failed;
+ }
+
+ xdev_vdbg(dev, "Registered dev with name=%s minor=%d, dev=%p\n",
+ dev->misc.name, dev->misc.minor, dev->misc.this_device);
+
+ SET_STATE_CLOSED(dev);
+ SET_PENDING_OFF(dev);
+ CLEAR_REMOTE_TEARDOWN(dev);
+ CLEAR_EOF(dev);
+
+ /* Add the device. */
+ spin_lock(&list_lock);
+ list_add(&dev->list_field, &xshmchr_chrdev_list);
+ spin_unlock(&list_lock);
+
+#ifdef CONFIG_DEBUG_FS
+ if (debugfsdir != NULL) {
+ dev->debugfs_device_dir =
+ debugfs_create_dir(dev->misc.name, debugfsdir);
+ debugfs_create_u32("conn_state", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir, &dev->conn_state);
+ debugfs_create_u32("num_open", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_open);
+ debugfs_create_u32("num_close", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_close);
+ debugfs_create_u32("num_init", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_init);
+ debugfs_create_u32("num_init_resp", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_init_resp);
+ debugfs_create_u32("num_deinit", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_deinit);
+ debugfs_create_u32("num_deinit_resp", S_IRUSR | S_IWUSR,
+ dev->debugfs_device_dir,
+ (u32 *) &dev->num_deinit_resp);
+ debugfs_create_u32("num_remote_teardown_ind",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_remote_teardown_ind);
+ debugfs_create_u32("num_read",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_read);
+ debugfs_create_u32("num_read_block",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_read_block);
+ debugfs_create_u32("num_read_bytes",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_read_bytes);
+ debugfs_create_u32("num_write",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_write);
+ debugfs_create_u32("num_write_block",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_write_block);
+ debugfs_create_u32("num_write_bytes",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) &dev->num_write_bytes);
+
+ debugfs_create_u32("rx_write_index",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.rx.write);
+ debugfs_create_u32("rx_read_index",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.rx.read);
+ debugfs_create_u32("rx_state",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.rx.state);
+ debugfs_create_u32("tx_write_index",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.tx.write);
+ debugfs_create_u32("tx_read_index",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.tx.read);
+ debugfs_create_u32("tx_state",
+ S_IRUSR | S_IWUSR, dev->debugfs_device_dir,
+ (u32 *) dev->xshm->cfg.tx.state);
+
+ }
+#endif
+ mutex_unlock(&dev->mutex);
+ return 0;
+err_failed:
+ xshmchr_put(dev);
+ return result;
+}
+
+static int chrdev_remove(struct xshmchr_char_dev *dev)
+{
+ if (!dev)
+ return -EBADF;
+
+ if (STATE_IS_OPEN(dev)) {
+ xdev_dbg(dev, "Device is opened "
+ "(dev=%p) file_mode = 0x%x\n",
+ dev, dev->file_mode);
+ SET_STATE_CLOSED(dev);
+ SET_PENDING_OFF(dev);
+ wake_up_interruptible_all(&dev->mgmt_wq);
+ }
+
+ if (mutex_lock_interruptible(&dev->mutex)) {
+ xdev_dbg(dev, "mutex_lock_interruptible got signalled\n");
+ xshmchr_put(dev);
+ return -ERESTARTSYS;
+ }
+
+ drain_ringbuf(dev);
+
+ misc_deregister(&dev->misc);
+
+ /* Remove from list. */
+ list_del(&dev->list_field);
+
+#ifdef CONFIG_DEBUG_FS
+ if (dev->debugfs_device_dir != NULL)
+ debugfs_remove_recursive(dev->debugfs_device_dir);
+#endif
+
+ mutex_unlock(&dev->mutex);
+ xshmchr_put(dev);
+ return 0;
+}
+
+static void cfshm_remove(struct xshm_dev *xshm)
+{
+ int err;
+
+ pr_devel("unregister pdev:%s chr=%s xshm=%p\n",
+ dev_name(&xshm->dev),
+ xshm->cfg.name, xshm);
+
+ err = chrdev_remove(xshm->driver_data);
+ if (err)
+ pr_debug("removing char-dev:%s failed.%d\n",
+ xshm->cfg.name, err);
+
+ xshm->ipc_rx_cb = NULL;
+ xshm->ipc_tx_release_cb = NULL;
+ xshm->open_cb = NULL;
+ xshm->close_cb = NULL;
+ xshm->driver_data = NULL;
+}
+
+static struct xshm_driver cfshm_drv = {
+ .mode = XSHM_STREAM_MODE,
+ .probe = cfshm_probe,
+ .remove = cfshm_remove,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+
+static int __init xshmchr_chrinit_module(void)
+{
+ int err;
+ pr_devel("xshm init\n");
+ spin_lock_init(&list_lock);
+
+ /* Register xshm driver. */
+ err = xshm_register_driver(&cfshm_drv);
+ if (err) {
+ printk(KERN_ERR "Could not register SHM driver: %d.\n",
+ err);
+ goto err_dev_register;
+ }
+
+#ifdef CONFIG_DEBUG_FS
+ debugfsdir = debugfs_create_dir("xshm_chr", NULL);
+#endif
+
+ err_dev_register:
+ return err;
+
+}
+
+static void __exit xshmchr_chrexit_module(void)
+{
+ int result;
+ struct xshmchr_char_dev *dev = NULL;
+
+ /* Unregister xshm driver. */
+ xshm_unregister_driver(&cfshm_drv);
+
+ do {
+ /* Remove any device (the first in the list). */
+ dev = find_device(-1, NULL, 0);
+ result = chrdev_remove(dev);
+ } while (result == 0);
+
+#ifdef CONFIG_DEBUG_FS
+ if (debugfsdir != NULL)
+ debugfs_remove_recursive(debugfsdir);
+#endif
+
+}
+
+module_init(xshmchr_chrinit_module);
+module_exit(xshmchr_chrexit_module);
--
1.7.1
--
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  Last update: 2011-12-16 11:53    [from the cache]
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