Messages in this thread | | | Date | Wed, 13 May 2009 19:11:44 +0200 | From | Cornelia Huck <> | Subject | Re: [PATCH] kernel:async function call:introduce async_run_inatomic(v2) |
| |
On Wed, 13 May 2009 23:51:39 +0800, tom.leiming@gmail.com wrote:
> From: Ming Lei <tom.leiming@gmail.com> > > The purpose of this function is to offer a simple way to schedule an > asynchronous thread from an atomic context, because there are not any > functions which can create and start a kernel thread in atomic contexts > now. We use async_running_no_sync as running list to make callers that > don't want to synchronize on cookies, so can avoid some side effects for > async_synchronize_full(). > > Part of note for async_run_inatomic and some guideline is from Cornelia Huck. > > Signed-off-by: Ming Lei <tom.leiming@gmail.com> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> > --- > include/linux/async.h | 2 ++ > kernel/async.c | 23 +++++++++++++++++++++++ > 2 files changed, 25 insertions(+), 0 deletions(-) > > diff --git a/include/linux/async.h b/include/linux/async.h > index 18ce92b..9ff62af 100644 > --- a/include/linux/async.h > +++ b/include/linux/async.h > @@ -16,6 +16,8 @@ > typedef u64 async_cookie_t; > typedef void (async_func_ptr) (void *data, async_cookie_t cookie); > > +extern int async_run_inatomic(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 8663f5b..cb527b3 100644 > --- a/kernel/async.c > +++ b/kernel/async.c > @@ -65,6 +65,7 @@ static async_cookie_t next_cookie = 1; > > static LIST_HEAD(async_pending); > static LIST_HEAD(async_running); > +static LIST_HEAD(async_running_no_sync); > static DEFINE_SPINLOCK(async_lock); > > static int async_enabled = 0; > @@ -222,6 +223,28 @@ static async_cookie_t __async_schedule(async_func_ptr *ptr, void *data, > return newcookie; > } > > + /** > + * async_run_inatomic - in atomic contexts schedule a function for > + * asynchronous execution
I'm not 100% sure whether kerneldoc likes split lines for the description.
"async_run_inatomic - schedule a function for asynchronous execution from atomic context without checkpointing" - but that's really a bit long...
> + * > + * @ptr: function to execute asynchronously > + * @data: data pointer to pass to the function > + * > + * Return zero if success, or else return others if failured
Returns zero on success, !zero on failure
> + * Note:
I'd move the description of the function's purpose before Note:.
> + * The purpose of this function is to offer a simple way to schedule an > + * asynchronous thread from an atomic context, because there are not any > + * functions which can create and start a kernel thread in atomic contexts > + * now.
I don't think the second part of the sentence is needed, this should only be mentioned in the patch description. I'd rather add
"Since it does not return a cookie for checkpointing, it is for callers that don't need later synchronization."
> We use async_running_no_sync as running list to make callers that > + * don't want to synchronize on cookies, so can avoid some side effects for > + * async_synchronize_full().
"async_run_inatomic() uses a distinct running list in order to avoid slowing down synchronization within the general domain."
(The cookie will still be checked when __lowest_in_progress() returns the cookie for the async_pending list, but I think that is negligible - and it would be a general issue for special domains.)
> + */ > +int async_run_inatomic(async_func_ptr *ptr, void *data) > +{ > + return !__async_schedule(ptr, data, &async_running_no_sync, 1); > +} > +EXPORT_SYMBOL_GPL(async_run_inatomic); > + > /** > * async_schedule - schedule a function for asynchronous execution > * @ptr: function to execute asynchronously
Btw: Do you have any specific use cases for this function in mind?
| |