* Denys Vlasenko <dvlas...@redhat.com> wrote: > SYSRET code path has a small irq-off block. > On this code path, TRACE_IRQS_ON can't be called right before interrupts > are enabled for real, we can't clobber registers there. > So current code does it earlier, in a safe place. > > But with this, TRACE_IRQS_OFF/ON frames just two fast instructions, > which is ridiculous: now most of irq-off block is _outside_ of the framing. > > Do the same thing that we do on SYSCALL entry: do not track this irq-off > block, > it is very small to ever cause noticeable irq latency. > > Be careful: make sure that "jnz int_ret_from_sys_call_irqs_off" now does > invoke TRACE_IRQS_OFF - move int_ret_from_sys_call_irqs_off label before > TRACE_IRQS_OFF.
> @@ -345,8 +346,8 @@ tracesys_phase2: > */ > GLOBAL(int_ret_from_sys_call) > DISABLE_INTERRUPTS(CLBR_NONE) > - TRACE_IRQS_OFF > int_ret_from_sys_call_irqs_off: > + TRACE_IRQS_OFF > movl $_TIF_ALLWORK_MASK,%edi > /* edi: mask to check */ This latter trick absolutely needs a comment, to keep future lockdep developers from wondering about the mismatch and the weird label placement ... Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/