[Question] I doublt on spin_lock again.
From: liyu
Date: Tue Nov 22 2005 - 21:03:51 EST
Hi, All.
I come here again.
I have two questions on spin_lock. these are:
1. I found these use spin_lock(&rq->lock) in set_user_nice(), but
not disable interrput ( e.g. when sys_nice() call it ), if the one
timer interrput come before we unlock the spin_lock, Shall
we dead lock here? Since the scheduler_tick() may try to hold the same
lock.
2. I also found some function name in its definition have some
postfix, I show here two classical examples:
static void double_rq_lock(runqueue_t *rq1, runqueue_t *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{ ... }
static void double_rq_unlock(runqueue_t *rq1, runqueue_t *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{ ... }
In the related header files, they are defined as two preprocess
macroes, are follow:
# define __acquires(x) __attribute__((context(0,1)))
# define __releases(x) __attribute__((context(1,0)))
# define __acquire(x) __context__(1)
# define __release(x) __context__(-1)
I guess they are some extensions of gcc for C language, but I did
not found any information in GCC manual.
Would you like reply these questions? Thank advanced.
-liyu
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