Re: [PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer
On (Tue) 25 Sep 2012 [15:47:15], sjur.brandel...@stericsson.com wrote:
From: Sjur Brændeland sjur.brandel...@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 for this cleanup; I should've caught it at the review of the
virtio-trace patchset itself -- sorry for that.
Signed-off-by: Sjur Brændeland sjur.brandel...@stericsson.com
cc: Rusty Russell ru...@rustcorp.com.au
cc: Michael S. Tsirkin m...@redhat.com
cc: Amit Shah amit.s...@redhat.com
cc: Linus Walleij linus.wall...@linaro.org
cc: Masami Hiramatsu masami.hiramatsu...@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;
unsigned int
+
kfree(buf-buf);
buf-buf isn't set to NULL in case sgpages is 0. Please set
buf-buf to NULL (and initialise other fields to default values) in
alloc_buf() (and leave this as is).
+
+ if (buf-sgpages)
This 'if' is not necessary; just having the for loop will do the right
thing.
+ 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)
Indentation is off.
{
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);
This looks hacky, along with the 'struct scatterlist sg[1]' in
port_buffer above. Use a pointer instead? At the least, please
include a comment in struct port_buffer mentioning sg has to be the
last element in the struct.
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);
That's a lot of GFP_ATOMICS; even for the cases that don't need them.
Maybe add a gfp param that only allocates GFP_ATOMIC memory from
callers in interrupt context. All existing code got switched to using
GFP_ATOMIC buffers as well, that's definitely not good.
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
RE: [PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer
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.
OK, good to hear that you agree to this kind of change. I'll do a respin
of this patch fixing the issues you have pointed out.
static void free_buf(struct port_buffer *buf)
{
+ int i;
+
kfree(buf-buf);
this should be done only when !buf-sgpages, or (see below)
Agree, I'll put this statement in an else branch to the if-statement 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)
I did this on purpose for the sake of simplicity, but I can
change this to something like:
alloc_size = sizeof(*buf) + sizeof(buf-sg) * max(nrbufs - 1, 1);
+ 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.
Agree, kzalloc() is better in this case.
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.
With this new patch alloc_buf() is used both for both RX and TX.
The out_vq did previously use malloc(). But I have preserved
the legacy behavior for the in_vq by calling memset() in function
fill_queue().
Thanks,
Sjur
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Re: [PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer
(2012/09/26 16:48), Sjur BRENDELAND wrote:
-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)
I did this on purpose for the sake of simplicity, but I can
change this to something like:
alloc_size = sizeof(*buf) + sizeof(buf-sg) * max(nrbufs - 1, 1);
You wouldn't need to change that. I think current code is enough simple
and reasonable. :)
Thanks!
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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RE: [PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer
Sjur BRENDELAND sjur.brandel...@stericsson.com writes: This allocates one redundant sg entry when nrbuf 0, but I think it is OK. (just a comment) I did this on purpose for the sake of simplicity, but I can change this to something like: alloc_size = sizeof(*buf) + sizeof(buf-sg) * max(nrbufs - 1, 1); That's why we use [0] in the definition (a GCC extension). Cheers, Rusty. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH 1/3] virtio_console:Merge struct buffer_token into struct port_buffer
(2012/09/25 22:47), sjur.brandel...@stericsson.com wrote:
From: Sjur Brændeland sjur.brandel...@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 Brændeland sjur.brandel...@stericsson.com
cc: Rusty Russell ru...@rustcorp.com.au
cc: Michael S. Tsirkin m...@redhat.com
cc: Amit Shah amit.s...@redhat.com
cc: Linus Walleij linus.wall...@linaro.org
cc: Masami Hiramatsu masami.hiramatsu...@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...@hitachi.com
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