Messages in this thread Patch in this message | | | Date | Wed, 24 Jun 2009 13:11:04 +0200 | From | Martin Schwidefsky <> | Subject | register_timer_hook use in arch/sh/oprofile |
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Hi Paul, following Ingo's suggestion I'm working on a patch to use a per-cpu hrtimer instead of the timer_hook for the oprofile ticks. Given that oprofile is the only user of the timer_hook I want to remove it completely. That way I came across the register_timer_hook call in arch/sh/oprofile/op_model_sh7750.c. Did this ever work? The startup of oprofile is done in two steps, on module load oprofile_init is called, on profiling start oprofile_start is called. Now for SH7750 this happens:
oprofile_init() ... oprofile_arch_init(&oprofile_ops); ... lmodel->init(); /* init() is sh7750_ppc_init for CPU_SH7750/CPU_7750S */ sh7750_ppc_reset(); register_timer_hook(sh7750_timer_notify); ... ... oprofile_timer_init(&oprofile_ops); ... ops->start = timer_start; ... ...
oprofile_start() ... oprofile_ops.start(); /* start() is timer_start set by oprofile_timer_init */ register_timer_hook(timer_notify); ...
As far as I can see the second register_timer_hook will fail because sh7750_timer_notify is already registered. That will cause oprofile_start to fail with -EBUSY, no?
My proposed solution for that particular problem would be to remove the sh7750_timer_notify function together with the register/unregister calls, see patch below. Then the sole caller of register_timer_hook would be in drivers/oprofile/timer_int.c and after that has been converted to hrtimer the whole timer_hook stuff could go away.
--- diff -urpN linux-2.6/arch/sh/oprofile/op_model_sh7750.c linux-2.6-patched/arch/sh/oprofile/op_model_sh7750.c --- linux-2.6/arch/sh/oprofile/op_model_sh7750.c 2009-06-10 05:05:27.000000000 +0200 +++ linux-2.6-patched/arch/sh/oprofile/op_model_sh7750.c 2009-06-24 13:07:08.000000000 +0200 @@ -95,12 +95,6 @@ static struct sh7750_ppc_register_config * behavior. */ -static int sh7750_timer_notify(struct pt_regs *regs) -{ - oprofile_add_sample(regs, 0); - return 0; -} - static u64 sh7750_read_counter(int counter) { return (u64)((u64)(__raw_readl(PMCTRH(counter)) & 0xffff) << 32) | @@ -231,14 +225,11 @@ static inline void sh7750_ppc_reset(void static int sh7750_ppc_init(void) { sh7750_ppc_reset(); - - return register_timer_hook(sh7750_timer_notify); + return 0; } static void sh7750_ppc_exit(void) { - unregister_timer_hook(sh7750_timer_notify); - sh7750_ppc_reset(); } --- -- blue skies, Martin.
"Reality continues to ruin my life." - Calvin.
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