On Fri, 24 Apr 2009 09:25:33 +0200
Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * Sachin Sant <sachinp@xxxxxxxxxx> wrote:
>
> > Today's next tree build(s390 allmodconfig) failed with
> >
> > kernel/built-in.o: In function `trace_softirq_entry'
> > include/trace/events/irq.h:42: undefined reference to
> > `'
> > include/trace/events/irq.h:42: undefined reference to
> > `__tracepoint_softirq_entry'
> > kernel/built-in.o: In function `trace_softirq_exit':
> > include/trace/events/irq.h:48: undefined reference to
> > `__tracepoint_softirq_exit'
> > include/trace/events/irq.h:48: undefined reference to
> > `__tracepoint_softirq_exit'
>
> Hm, that's weird - s390 does not build kernel/softirq.o? Hm, it does
> - softirq.o is an obj-y object.
s390 does build kernel/softirq.o. However it's anything but obvious to
me how the tracepoint infrastructure works. Too many #ifdefs, #define's
and #undefine's...
I would expect that struct __tracepoint_softirq_entry somehow gets
defined via one of the TRACE_FORMAT macros, no?
kernel/softirq.i has these parts wrt. __tracepoint_softirq_entry:
# 42 "include/trace/events/irq.h"
extern struct tracepoint __tracepoint_softirq_entry; static inline __attribute__((always_inline)) void trace_softirq_entry(struc
t softirq_action *h, struct softirq_action *vec) { if (__builtin_expect(!!(__tracepoint_softirq_entry.state), 0)) do { void **it
_func; do { } while (0); it_func = ({ typeof((&__tracepoint_softirq_entry)->funcs) _________p1 = (*(volatile typeof((&__tracepoi
nt_softirq_entry)->funcs) *)&((&__tracepoint_softirq_entry)->funcs)); do { } while(0); (_________p1); }); if (it_func) { do { ((
void(*)(struct softirq_action *h, struct softirq_action *vec))(*it_func))(h, vec); } while (*(++it_func)); } do { } while (0); }
while (0); } static inline __attribute__((always_inline)) int register_trace_softirq_entry(void (*probe)(struct softirq_action
*h, struct softirq_action *vec)) { return tracepoint_probe_register("softirq_entry", (void *)probe); } static inline __attribute
__((always_inline)) int unregister_trace_softirq_entry(void (*probe)(struct softirq_action *h, struct softirq_action *vec)) { re
turn tracepoint_probe_unregister("softirq_entry", (void *)probe); };
extern struct tracepoint __tracepoint_softirq_exit; static inline __attribute__((always_inline)) void trace_softirq_exit(struct
softirq_action *h, struct softirq_action *vec) { if (__builtin_expect(!!(__tracepoint_softirq_exit.state), 0)) do { void **it_fu
nc; do { } while (0); it_func = ({ typeof((&__tracepoint_softirq_exit)->funcs) _________p1 = (*(volatile typeof((&__tracepoint_s
oftirq_exit)->funcs) *)&((&__tracepoint_softirq_exit)->funcs)); do { } while(0); (_________p1); }); if (it_func) { do { ((void(*
)(struct softirq_action *h, struct softirq_action *vec))(*it_func))(h, vec); } while (*(++it_func)); } do { } while (0); } while
(0); } static inline __attribute__((always_inline)) int register_trace_softirq_exit(void (*probe)(struct softirq_action *h, str
uct softirq_action *vec)) { return tracepoint_probe_register("softirq_exit", (void *)probe); } static inline __attribute__((alwa
ys_inline)) int unregister_trace_softirq_exit(void (*probe)(struct softirq_action *h, struct softirq_action *vec)) { return trac
epoint_probe_unregister("softirq_exit", (void *)probe); };
__do_softirq looks like below. So I would expect some header file include dependency? Dunno...
void __do_softirq(void)
{
struct softirq_action *h;
__u32 pending;
int max_restart = 10;
int cpu;
pending = ((*((struct _lowcore *) 0)).softirq_pending);
account_system_vtime(((struct task_struct *const)(*((struct _lowcore *) 0)).current_task));
__local_bh_disable((unsigned long)__builtin_return_address(0));
do { ((struct task_struct *const)(*((struct _lowcore *) 0)).current_task)->softirq_context++; } while (0);
cpu = ((*((struct _lowcore *) 0)).cpu_nr);
restart:
(((*((struct _lowcore *) 0)).softirq_pending) = (0));
do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0);
h = softirq_vec;
do {
if (pending & 1) {
int prev_count = (current_thread_info()->preempt_count);
trace_softirq_entry(h, softirq_vec);
h->action(h);
trace_softirq_exit(h, softirq_vec);
if (__builtin_expect(!!(prev_count != (current_thread_info()->preempt_count)), 0)) {
printk("<3>" "huh, entered softirq %td %s %p"
"with preempt_count %08x,"
" exited with %08x?\n", h - softirq_vec,
softirq_to_name[h - softirq_vec],
h->action, prev_count, (current_thread_info()->preempt_count));
(current_thread_info()->preempt_count) = prev_count;
}
rcu_bh_qsctr_inc(cpu);
}
h++;
pending >>= 1;
} while (pending);
do { raw_local_irq_disable(); trace_hardirqs_off(); } while (0);
pending = ((*((struct _lowcore *) 0)).softirq_pending);
if (pending && --max_restart)
goto restart;
if (pending)
wakeup_softirqd();
do { ((struct task_struct *const)(*((struct _lowcore *) 0)).current_task)->softirq_context--; } while (0);
account_system_vtime(((struct task_struct *const)(*((struct _lowcore *) 0)).current_task));
_local_bh_enable();
}
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