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block: remove 'magic' from struct blk_plug

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I don't think we've ever caught any bugs with this, and there's the
list poisoning for the plug lists to catch uninitialized cases.
So remove the magic member and save 8 bytes in the struct.

Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2014-05-29 08:09:00 -06:00
parent cdef54dd85
commit 4d92a9beb3
2 changed files with 0 additions and 6 deletions
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5
block/blk-core.c
View file

@ -2957,8 +2957,6 @@ int kblockd_schedule_delayed_work_on(int cpu, struct delayed_work *dwork,
} }
EXPORT_SYMBOL(kblockd_schedule_delayed_work_on); EXPORT_SYMBOL(kblockd_schedule_delayed_work_on);
#define PLUG_MAGIC 0x91827364
/** /**
* blk_start_plug - initialize blk_plug and track it inside the task_struct * blk_start_plug - initialize blk_plug and track it inside the task_struct
* @plug: The &struct blk_plug that needs to be initialized * @plug: The &struct blk_plug that needs to be initialized
@ -2977,7 +2975,6 @@ void blk_start_plug(struct blk_plug *plug)
{ {
struct task_struct *tsk = current; struct task_struct *tsk = current;
plug->magic = PLUG_MAGIC;
INIT_LIST_HEAD(&plug->list); INIT_LIST_HEAD(&plug->list);
INIT_LIST_HEAD(&plug->mq_list); INIT_LIST_HEAD(&plug->mq_list);
INIT_LIST_HEAD(&plug->cb_list); INIT_LIST_HEAD(&plug->cb_list);
@ -3074,8 +3071,6 @@ void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
LIST_HEAD(list); LIST_HEAD(list);
unsigned int depth; unsigned int depth;
BUG_ON(plug->magic != PLUG_MAGIC);
flush_plug_callbacks(plug, from_schedule); flush_plug_callbacks(plug, from_schedule);
if (!list_empty(&plug->mq_list)) if (!list_empty(&plug->mq_list))

1
include/linux/blkdev.h
View file

@ -1060,7 +1060,6 @@ static inline void blk_post_runtime_resume(struct request_queue *q, int err) {}
* schedule() where blk_schedule_flush_plug() is called. * schedule() where blk_schedule_flush_plug() is called.
*/ */
struct blk_plug { struct blk_plug {
unsigned long magic; /* detect uninitialized use-cases */
struct list_head list; /* requests */ struct list_head list; /* requests */
struct list_head mq_list; /* blk-mq requests */ struct list_head mq_list; /* blk-mq requests */
struct list_head cb_list; /* md requires an unplug callback */ struct list_head cb_list; /* md requires an unplug callback */