On 01/31, Peter Zijlstra wrote:
>
> On Sat, Jan 31, 2015 at 10:32:23AM -0800, Linus Torvalds wrote:
> > On Fri, Jan 30, 2015 at 7:47 AM, Oleg Nesterov <o...@redhat.com> wrote:
> > >
> > > Perhaps sched_annotate_sleep() shouldn't depend on
> > > CONFIG_DEBUG_ATOMIC_SLEEP
> > > too...
> >
> > Ugh. That thing is horrible. The naming doesn't make it obvious at all
> > that it's actually making sure that we have state set to TASK_RUNNING,
> > and I could easily imagine that it would cause similar "busy-loops
> > while scheduling" issues if anybody ever uses it in the wrong context.
>
> The alternative was putting unconditional __set_task_state(TASK_RUNNING)
> things in a few code paths. I didn't want to cause the extra code in
> case we didn't need them. Particularly the include/net/sock.h one, as I
> know the network people are cycle counters.
And personally I agree. sched_annotate_sleep() looks self-documented, it
is clear that it is used to suppress the warning.
Still. Can't we avoid this subtle change in behaviour DEBUG_ATOMIC_SLEEP
adds?
Oleg.
--- x/include/linux/kernel.h
+++ x/include/linux/kernel.h
@@ -176,7 +176,7 @@ extern int _cond_resched(void);
*/
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
-# define sched_annotate_sleep() __set_current_state(TASK_RUNNING)
+# define sched_annotate_sleep() (current->task_state_change = 0)
#else
static inline void ___might_sleep(const char *file, int line,
int preempt_offset) { }
--- x/kernel/sched/core.c
+++ x/kernel/sched/core.c
@@ -7292,7 +7292,7 @@ void __might_sleep(const char *file, int
* since we will exit with TASK_RUNNING make sure we enter with it,
* otherwise we will destroy state.
*/
- if (WARN_ONCE(current->state != TASK_RUNNING,
+ if (WARN_ONCE(current->state != TASK_RUNNING &&
current->task_state_change,
"do not call blocking ops when !TASK_RUNNING; "
"state=%lx set at [<%p>] %pS\n",
current->state,
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
