No, it isn't. It is equivalent to *(long *)((char *)¤t_thread_info()->preempt_count + 1) += 1 which is of course completely bogus.
Sorry, I think I paste the redundant character for the codes (no '*' char at front or end of addql and subql instruction) I paste it again: ENTRY(inthandler) SAVE_ALL_INT GET_CURRENT(%d0) addql #1,%curptr@(TASK_INFO+TINFO_PREEMPT+1) /* put exception # in d0 */ movel %sp@(PT_VECTOR),%d0 swap %d0 /* extract bits 25:18 */ lsrl #2,%d0 andl #0x0ff,%d0 movel %sp,%sp@- movel %d0,%sp@- /* put vector # on stack */ auto_irqhandler_fixup = . + 2 jbsr process_int /* process the IRQ */ addql #8,%sp /* pop parameters off stack */ ret_from_interrupt: subql #1,%curptr@(TASK_INFO+TINFO_PREEMPT+1) jeq ret_from_last_interrupt 2: RESTORE_ALL ALIGN ret_from_last_interrupt: moveb %sp@(PT_SR),%d0 andl #(~ALLOWINT>>8)&0xff,%d0 jne 2b /* check if we need to do software interrupts */ tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING jeq .Lret_from_exception pea ret_from_exception jra do_softirq For code "addql #1,%curptr@(TASK_INFO+TINFO_PREEMPT+1)", My understanding is that %curptr@(TASK_INFO+TINFO_PREEMPT) is the address of current_thread_info()->preempt_count, and %curptr@(TASK_INFO+TINFO_PREEMPT+1) point to the second byte of preempt_count field (preempt_count field is 4 bytes). So this code sets value 1 to the second byte of preempt_count field. HARDIRQ_OFFSET equals (1 << HARDIRQ_SHIT) , and HARDIRQ_SHIFT value is 16, so I think this code equals current_thread_info()->preempt_count += HARDIRQ_OFFSET Am I wrong? Regards, Lanttor ------------------------------------------------------------------------ *From:* Andreas Schwab <schwab@xxxxxxxxxxxxxx> *Sent:* 07/02/2009 4:24:35 PM +0800 *To:* Lanttor <lanttor.guo@xxxxxxxxxxxxx> *CC:* linux-m68k@xxxxxxxxxxxxxxx, uClinux development list <uclinux-dev@xxxxxxxxxxx> *Subject:* Interrupt issue on m68k platform and some fix
Lanttor <lanttor.guo@xxxxxxxxxxxxx> writes:My understanding of "*addql #1,%curptr@(TASK_INFO+TINFO_PREEMPT+1)*" is that its meaning is equal to "current_thread_info()->preempt_count += HARDIRQ_OFFSET",No, it isn't. It is equivalent to *(long *)((char *)¤t_thread_info()->preempt_count + 1) += 1 which is of course completely bogus. Andreas.
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