On 2014/9/23 18:55, Tetsuo Handa wrote:

Zefan Li wrote:

quoted

Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happend

s/happend/happened/

quoted

@@ -1972,6 +1973,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
 TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
 TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
 
+TASK_PFA_TEST(SPREAD_PAGE, spread_page)
+TASK_PFA_SET(SPREAD_PAGE, spread_page)
+TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
+
+TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
+TASK_PFA_SET(SPREAD_SLAB, spread_slab)
+TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
+

I wonder how adding 3 macro lines differs from 3 inlined functions.
Personally, from LXR (source code browser) point of view, inlined functions
are more friendly than macros. Also, I wonder about the cost of extracting
macros in a file which is likely included by every file but referenced
by few files. Speak of SPREAD_PAGE and SPREAD_SLAB, they should be defined
as inlined functions in include/linux/cpuset.h rather than as macros in
include/linux/sched.h ?
.

Though tsk->atomic_flags were newly introduced in 3.17 merge window, we
already have 3 flags, and we may see more flags added.

Those macros make the code easier to read, and emacs and cscope can also
understand them.

I'd vote for this:

TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)

TASK_PFA_TEST(SPREAD_PAGE, spread_page)
TASK_PFA_SET(SPREAD_PAGE, spread_page)
TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)

TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
TASK_PFA_SET(SPREAD_SLAB, spread_slab)
TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)

over this:

static inline bool task_no_new_privs(struct task_struct *p)
{
	return test_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
}
static inline void task_set_new_privs(struct task_struct *p)
{
	set_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
}

static inline bool task_spread_page(struct task_struct *p)
{
	return test_bit(PFA_SPREAD_PAGE, &p->atomic_flags);
}
static inline void task_set_spread_page(struct task_struct *p)
{
	set_bit(PFA_SPREAD_PAGE, &p->atomic_flags);
}
static inline void task_clear_spread_page(struct task_struct *p)
{
	clear_bit(PFA_SPREAD_PAGE, &p->atomic_flags);
}

static inline bool task_spread_slab(struct task_struct *p)
{
	return test_bit(PFA_SPREAD_SLAB, &p->atomic_flags);
}
static inline void task_set_spread_slab(struct task_struct *p)
{
	set_bit(PFA_SPREAD_SLAB, &p->atomic_flags);
}
static inline void task_clear_spread_slab(struct task_struct *p)
{
	clear_bit(PFA_SPREAD_SLAB, &p->atomic_flags);
}