mirror of
https://github.com/torvalds/linux
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db7e007fd6
When using systemtap it was observed that our udelay implementation is rather suboptimal if being called from a kprobe handler installed by systemtap. The problem observed when a kprobe was installed on lock_acquired(). When the probe was hit the kprobe handler did call udelay, which set up an (internal) timer and reenabled interrupts (only the clock comparator interrupt) and waited for the interrupt. This is an optimization to avoid that the cpu is busy looping while waiting that enough time passes. The problem is that the interrupt handler still does call irq_enter()/irq_exit() which then again can lead to a deadlock, since some accounting functions may take locks as well. If one of these locks is the same, which caused lock_acquired() to be called, we have a nice deadlock. This patch reworks the udelay code for the interrupts disabled case to immediately leave the low level interrupt handler when the clock comparator interrupt happens. That way no C code is being called and the deadlock cannot happen anymore. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
79 lines
2.7 KiB
C
79 lines
2.7 KiB
C
#ifndef _ENTRY_H
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#define _ENTRY_H
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#include <linux/types.h>
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#include <linux/signal.h>
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#include <asm/ptrace.h>
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#include <asm/idle.h>
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extern void *restart_stack;
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extern unsigned long suspend_zero_pages;
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void system_call(void);
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void pgm_check_handler(void);
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void ext_int_handler(void);
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void io_int_handler(void);
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void mcck_int_handler(void);
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void restart_int_handler(void);
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void restart_call_handler(void);
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asmlinkage long do_syscall_trace_enter(struct pt_regs *regs);
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asmlinkage void do_syscall_trace_exit(struct pt_regs *regs);
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void do_protection_exception(struct pt_regs *regs);
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void do_dat_exception(struct pt_regs *regs);
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void addressing_exception(struct pt_regs *regs);
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void data_exception(struct pt_regs *regs);
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void default_trap_handler(struct pt_regs *regs);
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void divide_exception(struct pt_regs *regs);
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void execute_exception(struct pt_regs *regs);
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void hfp_divide_exception(struct pt_regs *regs);
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void hfp_overflow_exception(struct pt_regs *regs);
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void hfp_significance_exception(struct pt_regs *regs);
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void hfp_sqrt_exception(struct pt_regs *regs);
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void hfp_underflow_exception(struct pt_regs *regs);
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void illegal_op(struct pt_regs *regs);
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void operand_exception(struct pt_regs *regs);
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void overflow_exception(struct pt_regs *regs);
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void privileged_op(struct pt_regs *regs);
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void space_switch_exception(struct pt_regs *regs);
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void special_op_exception(struct pt_regs *regs);
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void specification_exception(struct pt_regs *regs);
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void transaction_exception(struct pt_regs *regs);
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void translation_exception(struct pt_regs *regs);
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void vector_exception(struct pt_regs *regs);
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void do_per_trap(struct pt_regs *regs);
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void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str);
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void syscall_trace(struct pt_regs *regs, int entryexit);
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void kernel_stack_overflow(struct pt_regs * regs);
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void do_signal(struct pt_regs *regs);
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void handle_signal32(struct ksignal *ksig, sigset_t *oldset,
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struct pt_regs *regs);
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void do_notify_resume(struct pt_regs *regs);
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void __init init_IRQ(void);
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void do_IRQ(struct pt_regs *regs, int irq);
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void do_restart(void);
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void __init startup_init(void);
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void die(struct pt_regs *regs, const char *str);
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int setup_profiling_timer(unsigned int multiplier);
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void __init time_init(void);
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int pfn_is_nosave(unsigned long);
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void s390_early_resume(void);
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unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip);
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struct s390_mmap_arg_struct;
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struct fadvise64_64_args;
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struct old_sigaction;
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long sys_rt_sigreturn(void);
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long sys_sigreturn(void);
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long sys_s390_personality(unsigned int personality);
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long sys_s390_runtime_instr(int command, int signum);
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long sys_s390_pci_mmio_write(unsigned long, const void __user *, size_t);
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long sys_s390_pci_mmio_read(unsigned long, void __user *, size_t);
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#endif /* _ENTRY_H */
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