[PATCH] kernel:async function call:introduce async_run

From: tom . leiming
Date: Tue May 12 2009 - 20:34:10 EST


From: Ming Lei <tom.leiming@xxxxxxxxx>

In fact, some async function call does not need to check, async_run
is right for this kind of function call. Also, async_run is very
suitable to used to start a thread in atomic context to do somthing,
for now there is no such kind of kernel api, eg. kthread_run
can not be started in atomic context.

This patch is againt my another patch:
kernel/async.c:introduce async_schedule*_atomic
please review.

Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
include/linux/async.h | 1 +
kernel/async.c | 24 +++++++++++++++++++++++-
2 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/include/linux/async.h b/include/linux/async.h
index ede9849..5390572 100644
--- a/include/linux/async.h
+++ b/include/linux/async.h
@@ -16,6 +16,7 @@
typedef u64 async_cookie_t;
typedef void (async_func_ptr) (void *data, async_cookie_t cookie);

+extern void async_run(async_func_ptr *ptr, void *data);
extern async_cookie_t async_schedule(async_func_ptr *ptr, void *data);
extern async_cookie_t async_schedule_domain(async_func_ptr *ptr, void *data,
struct list_head *list);
diff --git a/kernel/async.c b/kernel/async.c
index 6bf565b..9cc4670 100644
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -60,6 +60,7 @@ asynchronous and synchronous parts of the kernel.

static async_cookie_t next_cookie = 1;

+#define MAX_COOKIE (~0)
#define MAX_THREADS 256
#define MAX_WORK 32768

@@ -207,7 +208,10 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, \
entry->running = running;

spin_lock_irqsave(&async_lock, flags);
- newcookie = entry->cookie = next_cookie++;
+ if (atomic == 1)
+ newcookie = entry->cookie = next_cookie++;
+ else
+ newcookie = entry->cookie = MAX_COOKIE;
list_add_tail(&entry->list, &async_pending);
atomic_inc(&entry_count);
spin_unlock_irqrestore(&async_lock, flags);
@@ -216,6 +220,24 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, \
}

/**
+ * async_run - schedule a function for asynchronous execution
+ * @ptr: function to execute asynchronously
+ * @data: data pointer to pass to the function
+ *
+ * Note:we do not allocate a cookie for this kind of aysnchronous
+ * function to decrease the wait time of async_synchronize_full().
+ * In fact, some function does not need to check, async_run is right
+ * for this kind of function call. Also, async_run is very suitable to
+ * start a thread to do somthing in atomic context,for now there is no such
+ * kind of kernel api, eg. kthread_run can not be run in atomic context.
+ */
+void async_run(async_func_ptr *ptr, void *data)
+{
+ __async_schedule(ptr, data, &async_running, 2);
+}
+EXPORT_SYMBOL_GPL(async_run);
+
+/**
* async_schedule - schedule a function for asynchronous execution
* @ptr: function to execute asynchronously
* @data: data pointer to pass to the function
--
1.6.0.GIT

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