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sjur.brandeland at stericsson.com

2012-Sep-25 13:47 UTC

[PATCHv6 0/3] virtio_console: Add rproc_serial device

From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>

I thought rebasing rproc_serial to linux-next was going to be trivial.
But when starting the merge I realized that I had to refactor the
the patches from  Masami Hiramatsu. The splice support has the same issue
as I faced, with different type of buffers in the out_vq.
So I ended up refactoring the splice functionality. The code
size got smaller so hopefully this a step in the right direction.

This refactoring also make introduction of rproc_serial cleaner.

As requested I also added a patch for not initializing buffers.

I have tested the VIRTIO_CONSOLE device by looping large amount of data
through character device and tty, with lockdep and slub-debug on.
This looks stable for me. I've also done a simple test of splice.

Thanks,
Sjur

cc: Rusty Russell <rusty at rustcorp.com.au>
cc: Michael S. Tsirkin <mst at redhat.com>
cc: Amit Shah <amit.shah at redhat.com>
cc: Linus Walleij <linus.walleij at linaro.org>
cc: Masami Hiramatsu <masami.hiramatsu.pt at hitachi.com>


Sjur Br?ndeland (3):
  virtio_console:Merge struct buffer_token into struct port_buffer
  virtio_console: Add support for remoteproc serial
  virtio_console: Don't initialize buffers to zero

 drivers/char/virtio_console.c |  318 +++++++++++++++++++++++++++++------------
 include/linux/virtio_ids.h    |    1 +
 2 files changed, 228 insertions(+), 91 deletions(-)

-- 
1.7.5.4

sjur.brandeland at stericsson.com

2012-Sep-25 13:47 UTC

head link

[PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer

From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>

This merge reduces code size by unifying the approach for
sending scatter-lists and regular buffers. Any type of
write operation (splice, write, put_chars) will now allocate
a port_buffer and send_buf() and free_buf() can always be used.

Signed-off-by: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
cc: Rusty Russell <rusty at rustcorp.com.au>
cc: Michael S. Tsirkin <mst at redhat.com>
cc: Amit Shah <amit.shah at redhat.com>
cc: Linus Walleij <linus.walleij at linaro.org>
cc: Masami Hiramatsu <masami.hiramatsu.pt at hitachi.com>
---
 drivers/char/virtio_console.c |  141 ++++++++++++++++++-----------------------
 1 files changed, 62 insertions(+), 79 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 8ab9c3d..f4f7b04 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -111,6 +111,11 @@ struct port_buffer {
 	size_t len;
 	/* offset in the buf from which to consume data */
 	size_t offset;
+
+	/* If sgpages == 0 then buf is used, else sg is used */
+	unsigned int sgpages;
+
+	struct scatterlist sg[1];
 };
 
 /*
@@ -338,23 +343,46 @@ static inline bool use_multiport(struct ports_device
*portdev)
 
 static void free_buf(struct port_buffer *buf)
 {
+	int i;
+
 	kfree(buf->buf);
+
+	if (buf->sgpages)
+		for (i = 0; i < buf->sgpages; i++) {
+			struct page *page = sg_page(&buf->sg[i]);
+			if (!page)
+				break;
+			put_page(page);
+		}
+
 	kfree(buf);
 }
 
-static struct port_buffer *alloc_buf(size_t buf_size)
+static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
+				     int nrbufs)
 {
 	struct port_buffer *buf;
+	size_t alloc_size;
 
-	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+	/* Allocate buffer and the scatter list */
+	alloc_size = sizeof(*buf) + sizeof(struct scatterlist) * nrbufs;
+	buf = kmalloc(alloc_size, GFP_ATOMIC);
 	if (!buf)
 		goto fail;
-	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+
+	buf->sgpages = nrbufs;
+	if (nrbufs > 0)
+		return buf;
+
+	buf->buf = kmalloc(buf_size, GFP_ATOMIC);
 	if (!buf->buf)
 		goto free_buf;
 	buf->len = 0;
 	buf->offset = 0;
 	buf->size = buf_size;
+
+	/* Prepare scatter buffer for sending */
+	sg_init_one(buf->sg, buf->buf, buf_size);
 	return buf;
 
 free_buf:
@@ -476,52 +504,25 @@ static ssize_t send_control_msg(struct port *port,
unsigned int event,
 	return 0;
 }
 
-struct buffer_token {
-	union {
-		void *buf;
-		struct scatterlist *sg;
-	} u;
-	/* If sgpages == 0 then buf is used, else sg is used */
-	unsigned int sgpages;
-};
-
-static void reclaim_sg_pages(struct scatterlist *sg, unsigned int nrpages)
-{
-	int i;
-	struct page *page;
-
-	for (i = 0; i < nrpages; i++) {
-		page = sg_page(&sg[i]);
-		if (!page)
-			break;
-		put_page(page);
-	}
-	kfree(sg);
-}
 
 /* Callers must take the port->outvq_lock */
 static void reclaim_consumed_buffers(struct port *port)
 {
-	struct buffer_token *tok;
+	struct port_buffer *buf;
 	unsigned int len;
 
 	if (!port->portdev) {
 		/* Device has been unplugged.  vqs are already gone. */
 		return;
 	}
-	while ((tok = virtqueue_get_buf(port->out_vq, &len))) {
-		if (tok->sgpages)
-			reclaim_sg_pages(tok->u.sg, tok->sgpages);
-		else
-			kfree(tok->u.buf);
-		kfree(tok);
+	while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
+		free_buf(buf);
 		port->outvq_full = false;
 	}
 }
 
-static ssize_t __send_to_port(struct port *port, struct scatterlist *sg,
-			      int nents, size_t in_count,
-			      struct buffer_token *tok, bool nonblock)
+static ssize_t send_buf(struct port *port, struct port_buffer *buf, int nents,
+			      size_t in_count, bool nonblock)
 {
 	struct virtqueue *out_vq;
 	ssize_t ret;
@@ -534,7 +535,7 @@ static ssize_t __send_to_port(struct port *port, struct
scatterlist *sg,
 
 	reclaim_consumed_buffers(port);
 
-	ret = virtqueue_add_buf(out_vq, sg, nents, 0, tok, GFP_ATOMIC);
+	ret = virtqueue_add_buf(out_vq, buf->sg, nents, 0, buf, GFP_ATOMIC);
 
 	/* Tell Host to go! */
 	virtqueue_kick(out_vq);
@@ -559,8 +560,11 @@ static ssize_t __send_to_port(struct port *port, struct
scatterlist *sg,
 	 * we need to kmalloc a GFP_ATOMIC buffer each time the
 	 * console driver writes something out.
 	 */
-	while (!virtqueue_get_buf(out_vq, &len))
+	for (buf = virtqueue_get_buf(out_vq, &len); !buf;
+	     buf = virtqueue_get_buf(out_vq, &len))
 		cpu_relax();
+
+	free_buf(buf);
 done:
 	spin_unlock_irqrestore(&port->outvq_lock, flags);
 
@@ -572,36 +576,6 @@ done:
 	return in_count;
 }
 
-static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
-			bool nonblock)
-{
-	struct scatterlist sg[1];
-	struct buffer_token *tok;
-
-	tok = kmalloc(sizeof(*tok), GFP_ATOMIC);
-	if (!tok)
-		return -ENOMEM;
-	tok->sgpages = 0;
-	tok->u.buf = in_buf;
-
-	sg_init_one(sg, in_buf, in_count);
-
-	return __send_to_port(port, sg, 1, in_count, tok, nonblock);
-}
-
-static ssize_t send_pages(struct port *port, struct scatterlist *sg, int nents,
-			  size_t in_count, bool nonblock)
-{
-	struct buffer_token *tok;
-
-	tok = kmalloc(sizeof(*tok), GFP_ATOMIC);
-	if (!tok)
-		return -ENOMEM;
-	tok->sgpages = nents;
-	tok->u.sg = sg;
-
-	return __send_to_port(port, sg, nents, in_count, tok, nonblock);
-}
 
 /*
  * Give out the data that's requested from the buffer that we have
@@ -748,7 +722,7 @@ static ssize_t port_fops_write(struct file *filp, const char
__user *ubuf,
 			       size_t count, loff_t *offp)
 {
 	struct port *port;
-	char *buf;
+	struct port_buffer *buf;
 	ssize_t ret;
 	bool nonblock;
 
@@ -766,11 +740,11 @@ static ssize_t port_fops_write(struct file *filp, const
char __user *ubuf,
 
 	count = min((size_t)(32 * 1024), count);
 
-	buf = kmalloc(count, GFP_KERNEL);
+	buf = alloc_buf(port->out_vq, count, 0);
 	if (!buf)
 		return -ENOMEM;
 
-	ret = copy_from_user(buf, ubuf, count);
+	ret = copy_from_user(buf->buf, ubuf, count);
 	if (ret) {
 		ret = -EFAULT;
 		goto free_buf;
@@ -784,13 +758,13 @@ static ssize_t port_fops_write(struct file *filp, const
char __user *ubuf,
 	 * through to the host.
 	 */
 	nonblock = true;
-	ret = send_buf(port, buf, count, nonblock);
+	ret = send_buf(port, buf, 1, count, nonblock);
 
 	if (nonblock && ret > 0)
 		goto out;
 
 free_buf:
-	kfree(buf);
+	free_buf(buf);
 out:
 	return ret;
 }
@@ -856,6 +830,7 @@ static ssize_t port_fops_splice_write(struct pipe_inode_info
*pipe,
 	struct port *port = filp->private_data;
 	struct sg_list sgl;
 	ssize_t ret;
+	struct port_buffer *buf;
 	struct splice_desc sd = {
 		.total_len = len,
 		.flags = flags,
@@ -867,17 +842,17 @@ static ssize_t port_fops_splice_write(struct
pipe_inode_info *pipe,
 	if (ret < 0)
 		return ret;
 
+	buf = alloc_buf(port->out_vq, 0, pipe->nrbufs);
 	sgl.n = 0;
 	sgl.len = 0;
 	sgl.size = pipe->nrbufs;
-	sgl.sg = kmalloc(sizeof(struct scatterlist) * sgl.size, GFP_KERNEL);
-	if (unlikely(!sgl.sg))
-		return -ENOMEM;
-
+	sgl.sg = buf->sg;
 	sg_init_table(sgl.sg, sgl.size);
 	ret = __splice_from_pipe(pipe, &sd, pipe_to_sg);
 	if (likely(ret > 0))
-		ret = send_pages(port, sgl.sg, sgl.n, sgl.len, true);
+		ret = send_buf(port, buf, sgl.n, sgl.len, true);
+	else
+		free_buf(buf);
 
 	return ret;
 }
@@ -1031,6 +1006,7 @@ static const struct file_operations port_fops = {
 static int put_chars(u32 vtermno, const char *buf, int count)
 {
 	struct port *port;
+	struct port_buffer *port_buf;
 
 	if (unlikely(early_put_chars))
 		return early_put_chars(vtermno, buf, count);
@@ -1039,7 +1015,13 @@ static int put_chars(u32 vtermno, const char *buf, int
count)
 	if (!port)
 		return -EPIPE;
 
-	return send_buf(port, (void *)buf, count, false);
+	port_buf = alloc_buf(port->out_vq, count, 0);
+	if (port_buf == NULL)
+		return -ENOMEM;
+
+	memcpy(port_buf->buf, buf, count);
+
+	return send_buf(port, port_buf, 1, count, false);
 }
 
 /*
@@ -1260,10 +1242,11 @@ static unsigned int fill_queue(struct virtqueue *vq,
spinlock_t *lock)
 
 	nr_added_bufs = 0;
 	do {
-		buf = alloc_buf(PAGE_SIZE);
+		buf = alloc_buf(vq, PAGE_SIZE, 0);
 		if (!buf)
 			break;
 
+		memset(buf->buf, 0, PAGE_SIZE);
 		spin_lock_irq(lock);
 		ret = add_inbuf(vq, buf);
 		if (ret < 0) {
-- 
1.7.5.4

sjur.brandeland at stericsson.com

2012-Sep-25 13:47 UTC

head link

[PATCHv5 2/3] virtio_console: Add support for remoteproc serial

From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>

Add a simple serial connection driver called
VIRTIO_ID_RPROC_SERIAL (11) for communicating with a
remote processor in an asymmetric multi-processing
configuration.

This implementation reuses the existing virtio_console
implementation, and adds support for DMA allocation
of data buffers and disables use of tty console and
the virtio control queue.

Signed-off-by: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
cc: Rusty Russell <rusty at rustcorp.com.au>
cc: Michael S. Tsirkin <mst at redhat.com>
cc: Amit Shah <amit.shah at redhat.com>
cc: Ohad Ben-Cohen <ohad at wizery.com>
cc: Linus Walleij <linus.walleij at linaro.org>
cc: Arnd Bergmann <arnd at arndb.de>
---
Changes since v4:
- New baseline
- Use name is_rproc_enabled
- Renamed list and spin-lock used for pending deletion of dma buffers
- Minor style fixes: indentation, removed brace


 drivers/char/virtio_console.c |  184 +++++++++++++++++++++++++++++++++++++----
 include/linux/virtio_ids.h    |    1 +
 2 files changed, 170 insertions(+), 15 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index f4f7b04..faedd2c 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -37,8 +37,12 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/kconfig.h>
 #include "../tty/hvc/hvc_console.h"
 
+#define is_rproc_enabled IS_ENABLED(CONFIG_REMOTEPROC)
+
 /*
  * This is a global struct for storing common data for all the devices
  * this driver handles.
@@ -112,6 +116,15 @@ struct port_buffer {
 	/* offset in the buf from which to consume data */
 	size_t offset;
 
+	/* DMA address of buffer */
+	dma_addr_t dma;
+
+	/* Device we got DMA memory from */
+	struct device *dev;
+
+	/* List of pending dma buffers to free */
+	struct list_head list;
+
 	/* If sgpages == 0 then buf is used, else sg is used */
 	unsigned int sgpages;
 
@@ -330,6 +343,11 @@ static bool is_console_port(struct port *port)
 	return false;
 }
 
+static bool is_rproc_serial(const struct virtio_device *vdev)
+{
+	return is_rproc_enabled && vdev->id.device ==
VIRTIO_ID_RPROC_SERIAL;
+}
+
 static inline bool use_multiport(struct ports_device *portdev)
 {
 	/*
@@ -341,32 +359,84 @@ static inline bool use_multiport(struct ports_device
*portdev)
 	return portdev->vdev->features[0] & (1 <<
VIRTIO_CONSOLE_F_MULTIPORT);
 }
 
+static DEFINE_SPINLOCK(dma_bufs_lock);
+static LIST_HEAD(pending_free_dma_bufs);
+
 static void free_buf(struct port_buffer *buf)
 {
 	int i;
+	unsigned long flags;
 
-	kfree(buf->buf);
+	if (!buf->dev)
+		kfree(buf->buf);
 
-	if (buf->sgpages)
+	if (buf->sgpages) {
 		for (i = 0; i < buf->sgpages; i++) {
 			struct page *page = sg_page(&buf->sg[i]);
 			if (!page)
 				break;
 			put_page(page);
 		}
+		return;
+	}
+
+	if (buf->dev && is_rproc_enabled) {
+
+		/* dma_free_coherent requires interrupts to be enabled. */
+		if (irqs_disabled()) {
+			/* queue up dma-buffers to be freed later */
+			spin_lock_irqsave(&dma_bufs_lock, flags);
+			list_add_tail(&buf->list, &pending_free_dma_bufs);
+			spin_unlock_irqrestore(&dma_bufs_lock, flags);
+			return;
+		}
+		dma_free_coherent(buf->dev, buf->size, buf->buf, buf->dma);
+
+		/* Release device refcnt and allow it to be freed */
+		might_sleep();
+		put_device(buf->dev);
+	}
 
 	kfree(buf);
 }
 
+static void reclaim_dma_bufs(void)
+{
+	unsigned long flags;
+	struct port_buffer *buf, *tmp;
+	LIST_HEAD(tmp_list);
+
+	WARN_ON(irqs_disabled());
+	if (list_empty(&pending_free_dma_bufs))
+		return;
+
+	BUG_ON(!is_rproc_enabled);
+
+	/* Create a copy of the pending_free_dma_bufs while holding the lock*/
+	spin_lock_irqsave(&dma_bufs_lock, flags);
+	list_cut_position(&tmp_list, &pending_free_dma_bufs,
+			  pending_free_dma_bufs.prev);
+	spin_unlock_irqrestore(&dma_bufs_lock, flags);
+
+	/* Release the dma buffers, without irqs enabled */
+	list_for_each_entry_safe(buf, tmp, &tmp_list, list) {
+		list_del(&buf->list);
+		free_buf(buf);
+	}
+}
+
 static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t buf_size,
 				     int nrbufs)
 {
 	struct port_buffer *buf;
 	size_t alloc_size;
 
+	if (is_rproc_serial(vq->vdev) && !irqs_disabled())
+		reclaim_dma_bufs();
+
 	/* Allocate buffer and the scatter list */
 	alloc_size = sizeof(*buf) + sizeof(struct scatterlist) * nrbufs;
-	buf = kmalloc(alloc_size, GFP_ATOMIC);
+	buf = kzalloc(alloc_size, GFP_ATOMIC);
 	if (!buf)
 		goto fail;
 
@@ -374,11 +444,30 @@ static struct port_buffer *alloc_buf(struct virtqueue *vq,
size_t buf_size,
 	if (nrbufs > 0)
 		return buf;
 
-	buf->buf = kmalloc(buf_size, GFP_ATOMIC);
+	if (is_rproc_serial(vq->vdev)) {
+		/*
+		 * Allocate DMA memory from ancestor. When a virtio
+		 * device is created by remoteproc, the DMA memory is
+		 * associated with the grandparent device:
+		 * vdev => rproc => platform-dev.
+		 * The code here would have been less quirky if
+		 * DMA_MEMORY_INCLUDES_CHILDREN had been supported
+		 * in dma-coherent.c
+		 */
+		if (!vq->vdev->dev.parent || !vq->vdev->dev.parent->parent)
+			goto free_buf;
+		buf->dev = vq->vdev->dev.parent->parent;
+
+		/* Increase device refcnt to avoid freeing it*/
+		get_device(buf->dev);
+		buf->buf = dma_alloc_coherent(buf->dev, buf_size, &buf->dma,
+					      GFP_ATOMIC);
+	} else {
+		buf->buf = kmalloc(buf_size, GFP_ATOMIC);
+	}
+
 	if (!buf->buf)
 		goto free_buf;
-	buf->len = 0;
-	buf->offset = 0;
 	buf->size = buf_size;
 
 	/* Prepare scatter buffer for sending */
@@ -838,6 +927,10 @@ static ssize_t port_fops_splice_write(struct
pipe_inode_info *pipe,
 		.u.data = &sgl,
 	};
 
+	/* rproc_serial does not support splice */
+	if (is_rproc_serial(port->out_vq->vdev))
+		return -EINVAL;
+
 	ret = wait_port_writable(port, filp->f_flags & O_NONBLOCK);
 	if (ret < 0)
 		return ret;
@@ -902,6 +995,8 @@ static int port_fops_release(struct inode *inode, struct
file *filp)
 	reclaim_consumed_buffers(port);
 	spin_unlock_irq(&port->outvq_lock);
 
+	if (is_rproc_serial(port->portdev->vdev) && !irqs_disabled())
+		reclaim_dma_bufs();
 	/*
 	 * Locks aren't necessary here as a port can't be opened after
 	 * unplug, and if a port isn't unplugged, a kref would already
@@ -1058,7 +1153,10 @@ static void resize_console(struct port *port)
 		return;
 
 	vdev = port->portdev->vdev;
-	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
+
+	/* Don't test F_SIZE at all if we're rproc: not a valid feature! */
+	if (!is_rproc_serial(vdev) &&
+	    virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
 		hvc_resize(port->cons.hvc, port->cons.ws);
 }
 
@@ -1339,10 +1437,18 @@ static int add_port(struct ports_device *portdev, u32
id)
 		goto free_device;
 	}
 
-	/*
-	 * If we're not using multiport support, this has to be a console port
-	 */
-	if (!use_multiport(port->portdev)) {
+	if (is_rproc_serial(port->portdev->vdev))
+		/*
+		 * For rproc_serial assume remote processor is connected.
+		 * rproc_serial does not want the console port, only
+		 * the generic port implementation.
+		 */
+		port->host_connected = true;
+	else if (!use_multiport(port->portdev)) {
+		/*
+		 * If we're not using multiport support,
+		 * this has to be a console port.
+		 */
 		err = init_port_console(port);
 		if (err)
 			goto free_inbufs;
@@ -1418,6 +1524,15 @@ static void remove_port_data(struct port *port)
 	/* Remove buffers we queued up for the Host to send us data in. */
 	while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
 		free_buf(buf);
+
+	/*
+	 * Remove buffers from out queue for rproc-serial. We cannot afford
+	 * to leak any DMA mem, so reclaim this memory even if this might be
+	 * racy for the remote processor.
+	 */
+	if (is_rproc_serial(port->portdev->vdev))
+		while ((buf = virtqueue_detach_unused_buf(port->out_vq)))
+			free_buf(buf);
 }
 
 /*
@@ -1865,11 +1980,15 @@ static int __devinit virtcons_probe(struct virtio_device
*vdev)
 
 	multiport = false;
 	portdev->config.max_nr_ports = 1;
-	if (virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
-			      offsetof(struct virtio_console_config,
-				       max_nr_ports),
-			      &portdev->config.max_nr_ports) == 0)
+
+	/* Don't test MULTIPORT at all if we're rproc: not a valid feature! */
+	if (!is_rproc_serial(vdev) &&
+	    virtio_config_val(vdev, VIRTIO_CONSOLE_F_MULTIPORT,
+				  offsetof(struct virtio_console_config,
+					   max_nr_ports),
+				  &portdev->config.max_nr_ports) == 0) {
 		multiport = true;
+	}
 
 	err = init_vqs(portdev);
 	if (err < 0) {
@@ -1979,6 +2098,16 @@ static unsigned int features[] = {
 	VIRTIO_CONSOLE_F_MULTIPORT,
 };
 
+static struct virtio_device_id rproc_serial_id_table[] = {
+#if IS_ENABLED(CONFIG_REMOTEPROC)
+	{ VIRTIO_ID_RPROC_SERIAL, VIRTIO_DEV_ANY_ID },
+#endif
+	{ 0 },
+};
+
+static unsigned int rproc_serial_features[] = {
+};
+
 #ifdef CONFIG_PM
 static int virtcons_freeze(struct virtio_device *vdev)
 {
@@ -2063,6 +2192,20 @@ static struct virtio_driver virtio_console = {
 #endif
 };
 
+/*
+ * virtio_rproc_serial refers to __devinit function which causes
+ * section mismatch warnings. So use __refdata to silence warnings.
+ */
+static struct virtio_driver __refdata virtio_rproc_serial = {
+	.feature_table = rproc_serial_features,
+	.feature_table_size = ARRAY_SIZE(rproc_serial_features),
+	.driver.name =	"virtio_rproc_serial",
+	.driver.owner =	THIS_MODULE,
+	.id_table =	rproc_serial_id_table,
+	.probe =	virtcons_probe,
+	.remove =	virtcons_remove,
+};
+
 static int __init init(void)
 {
 	int err;
@@ -2087,7 +2230,15 @@ static int __init init(void)
 		pr_err("Error %d registering virtio driver\n", err);
 		goto free;
 	}
+	err = register_virtio_driver(&virtio_rproc_serial);
+	if (err < 0) {
+		pr_err("Error %d registering virtio rproc serial driver\n",
+		       err);
+		goto unregister;
+	}
 	return 0;
+unregister:
+	unregister_virtio_driver(&virtio_console);
 free:
 	if (pdrvdata.debugfs_dir)
 		debugfs_remove_recursive(pdrvdata.debugfs_dir);
@@ -2097,7 +2248,10 @@ free:
 
 static void __exit fini(void)
 {
+	reclaim_dma_bufs();
+
 	unregister_virtio_driver(&virtio_console);
+	unregister_virtio_driver(&virtio_rproc_serial);
 
 	class_destroy(pdrvdata.class);
 	if (pdrvdata.debugfs_dir)
diff --git a/include/linux/virtio_ids.h b/include/linux/virtio_ids.h
index 270fb22..cb28b52 100644
--- a/include/linux/virtio_ids.h
+++ b/include/linux/virtio_ids.h
@@ -37,5 +37,6 @@
 #define VIRTIO_ID_RPMSG		7 /* virtio remote processor messaging */
 #define VIRTIO_ID_SCSI		8 /* virtio scsi */
 #define VIRTIO_ID_9P		9 /* 9p virtio console */
+#define VIRTIO_ID_RPROC_SERIAL	11 /* virtio remoteproc serial link */
 
 #endif /* _LINUX_VIRTIO_IDS_H */
-- 
1.7.5.4

sjur.brandeland at stericsson.com

2012-Sep-25 13:47 UTC

head link

[PATCH 3/3] virtio_console: Don't initialize buffers to zero

From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>

Skip initializing the receive buffers.

Signed-off-by: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
---
 drivers/char/virtio_console.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index faedd2c..e7d8787 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1344,7 +1344,6 @@ static unsigned int fill_queue(struct virtqueue *vq,
spinlock_t *lock)
 		if (!buf)
 			break;
 
-		memset(buf->buf, 0, PAGE_SIZE);
 		spin_lock_irq(lock);
 		ret = add_inbuf(vq, buf);
 		if (ret < 0) {
-- 
1.7.5.4

Masami Hiramatsu

2012-Sep-26 02:44 UTC

head link

[PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer

(2012/09/25 22:47), sjur.brandeland at stericsson.com
wrote:> From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
> 
> This merge reduces code size by unifying the approach for
> sending scatter-lists and regular buffers. Any type of
> write operation (splice, write, put_chars) will now allocate
> a port_buffer and send_buf() and free_buf() can always be used.
Thanks!
This looks much nicer and simpler. I just have some comments below.
> Signed-off-by: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
> cc: Rusty Russell <rusty at rustcorp.com.au>
> cc: Michael S. Tsirkin <mst at redhat.com>
> cc: Amit Shah <amit.shah at redhat.com>
> cc: Linus Walleij <linus.walleij at linaro.org>
> cc: Masami Hiramatsu <masami.hiramatsu.pt at hitachi.com>
> ---
>  drivers/char/virtio_console.c |  141
++++++++++++++++++-----------------------
>  1 files changed, 62 insertions(+), 79 deletions(-)
> 
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 8ab9c3d..f4f7b04 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -111,6 +111,11 @@ struct port_buffer {
>  	size_t len;
>  	/* offset in the buf from which to consume data */
>  	size_t offset;
> +
> +	/* If sgpages == 0 then buf is used, else sg is used */
> +	unsigned int sgpages;
> +
> +	struct scatterlist sg[1];
>  };
>  
>  /*
> @@ -338,23 +343,46 @@ static inline bool use_multiport(struct ports_device
*portdev)
>  
>  static void free_buf(struct port_buffer *buf)
>  {
> +	int i;
> +
>  	kfree(buf->buf);
this should be done only when !buf->sgpages, or (see below)
> +
> +	if (buf->sgpages)
> +		for (i = 0; i < buf->sgpages; i++) {
> +			struct page *page = sg_page(&buf->sg[i]);
> +			if (!page)
> +				break;
> +			put_page(page);
> +		}
> +
>  	kfree(buf);
>  }
>  
> -static struct port_buffer *alloc_buf(size_t buf_size)
> +static struct port_buffer *alloc_buf(struct virtqueue *vq, size_t
buf_size,
> +				     int nrbufs)
>  {
>  	struct port_buffer *buf;
> +	size_t alloc_size;
>  
> -	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
> +	/* Allocate buffer and the scatter list */
> +	alloc_size = sizeof(*buf) + sizeof(struct scatterlist) * nrbufs;
This allocates one redundant sg entry when nrbuf > 0,
but I think it is OK. (just a comment)
> +	buf = kmalloc(alloc_size, GFP_ATOMIC);
This should be kzalloc(), or buf->buf and others are not initialized,
which will cause unexpected kfree bug at kfree(buf->buf) in free_buf.
>  	if (!buf)
>  		goto fail;
> -	buf->buf = kzalloc(buf_size, GFP_KERNEL);
> +
> +	buf->sgpages = nrbufs;
> +	if (nrbufs > 0)
> +		return buf;
> +
> +	buf->buf = kmalloc(buf_size, GFP_ATOMIC);
You can also use kzalloc here as previous code does.
But if the reason why using kzalloc comes from the security,
I think kmalloc is enough here, since the host can access
all the guest pages anyway.
>  	if (!buf->buf)
>  		goto free_buf;
>  	buf->len = 0;
>  	buf->offset = 0;
>  	buf->size = buf_size;
> +
> +	/* Prepare scatter buffer for sending */
> +	sg_init_one(buf->sg, buf->buf, buf_size);
>  	return buf;
>  
>  free_buf:
Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt at hitachi.com

Amit Shah

2012-Sep-28 12:48 UTC

head link

[PATCHv6 0/3] virtio_console: Add rproc_serial device

On (Tue) 25 Sep 2012 [15:47:14], sjur.brandeland at stericsson.com
wrote:> From: Sjur Br?ndeland <sjur.brandeland at stericsson.com>
> 
> I thought rebasing rproc_serial to linux-next was going to be trivial.
> But when starting the merge I realized that I had to refactor the
> the patches from  Masami Hiramatsu. The splice support has the same issue
> as I faced, with different type of buffers in the out_vq.
> So I ended up refactoring the splice functionality. The code
> size got smaller so hopefully this a step in the right direction.
> 
> This refactoring also make introduction of rproc_serial cleaner.
> 
> As requested I also added a patch for not initializing buffers.
> 
> I have tested the VIRTIO_CONSOLE device by looping large amount of data
> through character device and tty, with lockdep and slub-debug on.
> This looks stable for me. I've also done a simple test of splice.
Thanks; I just passed these patches through my testsuite and things
are working fine.  I'll review them in some time.

		Amit

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