Re: [ros-dev] [ros-diffs] [cgutman] 54418: [HALX86] - Do not allow software interrupts to preempt code running with interrupts disabled during KfLowerIrql

[Aleksey Bragin]

I would like to ask our kernel gurus if this one is correct.

WBR,
Aleksey Bragin.

On 18.11.2011 22:53, cgutman(a)svn.reactos.org wrote:
>   Author: cgutman
>  Date: Fri Nov 18 18:53:41 2011
>  New Revision: 54418
>
>  URL: http://svn.reactos.org/svn/reactos?rev=54418&view=rev
>  Log:
>  [HALX86]
>  - Do not allow software interrupts to preempt code running with interrupts disabled
> during KfLowerIrql
>
>  Modified:
>       trunk/reactos/hal/halx86/up/pic.c
>
>  Modified: trunk/reactos/hal/halx86/up/pic.c
>  URL:
> http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/up/pic.c?rev=54…
>  ==============================================================================
>  --- trunk/reactos/hal/halx86/up/pic.c [iso-8859-1] (original)
>  +++ trunk/reactos/hal/halx86/up/pic.c [iso-8859-1] Fri Nov 18 18:53:41 2011
>  @@ -665,26 +665,30 @@
>
>        /* Set old IRQL */
>        Pcr->Irql = OldIrql;
>  -
>  -    /* Check for pending software interrupts and compare with current IRQL */
>  -    PendingIrqlMask = Pcr->IRR&  FindHigherIrqlMask[OldIrql];
>  -    if (PendingIrqlMask)
>  -    {
>  -        /* Check if pending IRQL affects hardware state */
>  -        BitScanReverse(&PendingIrql, PendingIrqlMask);
>  -        if (PendingIrql>  DISPATCH_LEVEL)
>  +
>  +    /* Make sure interrupts were enabled */
>  +    if (EFlags&  EFLAGS_INTERRUPT_MASK)
>  +    {
>  +        /* Check for pending software interrupts and compare with current IRQL */
>  +        PendingIrqlMask = Pcr->IRR&  FindHigherIrqlMask[OldIrql];
>  +        if (PendingIrqlMask)
>            {
>  -            /* Set new PIC mask */
>  -            Mask.Both = Pcr->IDR;
>  -            __outbyte(PIC1_DATA_PORT, Mask.Master);
>  -            __outbyte(PIC2_DATA_PORT, Mask.Slave);
>  -
>  -            /* Clear IRR bit */
>  -            Pcr->IRR ^= (1<<  PendingIrql);
>  +            /* Check if pending IRQL affects hardware state */
>  +            BitScanReverse(&PendingIrql, PendingIrqlMask);
>  +            if (PendingIrql>  DISPATCH_LEVEL)
>  +            {
>  +                /* Set new PIC mask */
>  +                Mask.Both = Pcr->IDR;
>  +                __outbyte(PIC1_DATA_PORT, Mask.Master);
>  +                __outbyte(PIC2_DATA_PORT, Mask.Slave);
>  +
>  +                /* Clear IRR bit */
>  +                Pcr->IRR ^= (1<<  PendingIrql);
>  +            }
>  +
>  +            /* Now handle pending interrupt */
>  +            SWInterruptHandlerTable[PendingIrql]();
>            }
>  -
>  -        /* Now handle pending interrupt */
>  -        SWInterruptHandlerTable[PendingIrql]();
>        }
>
>        /* Restore interrupt state */
>
>