The hardware automatically disable the IRQ interrupt before jumping to the
interrupt or exception vector. Therefore, the preempt_disable() operation
in this_cpu_read() after macro expansion is unnecessary. In fact, function
this_cpu_read() may trigger scheduling, see pseudocode below.
Pseudocode of this_cpu_read(xx):
preempt_disable_notrace();
raw_cpu_read(xx);
if (unlikely(__preempt_count_dec_and_test()))
__preempt_schedule_notrace();
Therefore, use raw_cpu_* instead of this_cpu_* to eliminate potential
hazards. At the very least, it reduces a few lines of assembly code.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
{
unsigned long tsk_stk = (unsigned long)current->stack;
#ifdef CONFIG_IRQSTACKS
- unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
+ unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
#endif
- unsigned long ovf_stk = (unsigned long)this_cpu_read(overflow_stack_ptr);
+ unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
console_verbose();
pr_emerg("Insufficient stack space to handle exception!");