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authorStefani Seibold <stefani@seibold.net>2009-12-21 14:37:26 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-22 14:17:55 -0800
commit45465487897a1c6d508b14b904dc5777f7ec7e04 (patch)
tree935c8dae68dc793ff2f795d57cf027531475cd53 /net/dccp
parent2ec91eec47f713e3d158ba5b28a24a85a2cf3650 (diff)
kfifo: move struct kfifo in place
This is a new generic kernel FIFO implementation. The current kernel fifo API is not very widely used, because it has to many constrains. Only 17 files in the current 2.6.31-rc5 used it. FIFO's are like list's a very basic thing and a kfifo API which handles the most use case would save a lot of development time and memory resources. I think this are the reasons why kfifo is not in use: - The API is to simple, important functions are missing - A fifo can be only allocated dynamically - There is a requirement of a spinlock whether you need it or not - There is no support for data records inside a fifo So I decided to extend the kfifo in a more generic way without blowing up the API to much. The new API has the following benefits: - Generic usage: For kernel internal use and/or device driver. - Provide an API for the most use case. - Slim API: The whole API provides 25 functions. - Linux style habit. - DECLARE_KFIFO, DEFINE_KFIFO and INIT_KFIFO Macros - Direct copy_to_user from the fifo and copy_from_user into the fifo. - The kfifo itself is an in place member of the using data structure, this save an indirection access and does not waste the kernel allocator. - Lockless access: if only one reader and one writer is active on the fifo, which is the common use case, no additional locking is necessary. - Remove spinlock - give the user the freedom of choice what kind of locking to use if one is required. - Ability to handle records. Three type of records are supported: - Variable length records between 0-255 bytes, with a record size field of 1 bytes. - Variable length records between 0-65535 bytes, with a record size field of 2 bytes. - Fixed size records, which no record size field. - Preserve memory resource. - Performance! - Easy to use! This patch: Since most users want to have the kfifo as part of another object, reorganize the code to allow including struct kfifo in another data structure. This requires changing the kfifo_alloc and kfifo_init prototypes so that we pass an existing kfifo pointer into them. This patch changes the implementation and all existing users. [akpm@linux-foundation.org: fix warning] Signed-off-by: Stefani Seibold <stefani@seibold.net> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com> Acked-by: Andi Kleen <ak@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/dccp')
-rw-r--r--net/dccp/probe.c20
1 files changed, 9 insertions, 11 deletions
diff --git a/net/dccp/probe.c b/net/dccp/probe.c
index dc328425fa20..6230ceb0823e 100644
--- a/net/dccp/probe.c
+++ b/net/dccp/probe.c
@@ -43,7 +43,7 @@ static int bufsize = 64 * 1024;
static const char procname[] = "dccpprobe";
static struct {
- struct kfifo *fifo;
+ struct kfifo fifo;
spinlock_t lock;
wait_queue_head_t wait;
struct timespec tstart;
@@ -67,7 +67,7 @@ static void printl(const char *fmt, ...)
len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
va_end(args);
- kfifo_put(dccpw.fifo, tbuf, len);
+ kfifo_put(&dccpw.fifo, tbuf, len);
wake_up(&dccpw.wait);
}
@@ -109,7 +109,7 @@ static struct jprobe dccp_send_probe = {
static int dccpprobe_open(struct inode *inode, struct file *file)
{
- kfifo_reset(dccpw.fifo);
+ kfifo_reset(&dccpw.fifo);
getnstimeofday(&dccpw.tstart);
return 0;
}
@@ -131,11 +131,11 @@ static ssize_t dccpprobe_read(struct file *file, char __user *buf,
return -ENOMEM;
error = wait_event_interruptible(dccpw.wait,
- __kfifo_len(dccpw.fifo) != 0);
+ __kfifo_len(&dccpw.fifo) != 0);
if (error)
goto out_free;
- cnt = kfifo_get(dccpw.fifo, tbuf, len);
+ cnt = kfifo_get(&dccpw.fifo, tbuf, len);
error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
out_free:
@@ -156,10 +156,8 @@ static __init int dccpprobe_init(void)
init_waitqueue_head(&dccpw.wait);
spin_lock_init(&dccpw.lock);
- dccpw.fifo = kfifo_alloc(bufsize, GFP_KERNEL, &dccpw.lock);
- if (IS_ERR(dccpw.fifo))
- return PTR_ERR(dccpw.fifo);
-
+ if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL, &dccpw.lock))
+ return ret;
if (!proc_net_fops_create(&init_net, procname, S_IRUSR, &dccpprobe_fops))
goto err0;
@@ -172,14 +170,14 @@ static __init int dccpprobe_init(void)
err1:
proc_net_remove(&init_net, procname);
err0:
- kfifo_free(dccpw.fifo);
+ kfifo_free(&dccpw.fifo);
return ret;
}
module_init(dccpprobe_init);
static __exit void dccpprobe_exit(void)
{
- kfifo_free(dccpw.fifo);
+ kfifo_free(&dccpw.fifo);
proc_net_remove(&init_net, procname);
unregister_jprobe(&dccp_send_probe);

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