Please use a more descriptive title. Suggest "megasas: Fix
Cao jin <caoj.f...@cn.fujitsu.com> writes:
> msi_init returns non-zero value on both failure and success
This is a sentence, should end with a period.
Bug's impact? Here's my guess.
msi_init() either succeeds and returns 0x50, or fails and returns a
negative errno. If it succeeds, we mistakenly clear
MEGASAS_MASK_USE_MSI. Its only use is in megasas_scsi_uninit(), via
megasas_use_msi(). There, we fail to msi_uninit() on unrealize due to
the bug.
I figure that's harmless if we destroy the device next. This is the
common case.
If we don't destroy it, and then realize it again, msi_init() fails,
because there's no space at 0x50: the MSI capability we neglected to
delete is still there. We report the problem to the user, then realize
the device anyway (I hate that, but it's a separate issue).
Marcel, can you confirm my analysis?
> Signed-off-by: Cao jin <caoj.f...@cn.fujitsu.com>
> CC: Hannes Reinecke <h...@suse.de>
> CC: Paolo Bonzini <pbonz...@redhat.com>
> ---
> hw/scsi/megasas.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
> index a63a581..56fb645 100644
> --- a/hw/scsi/megasas.c
> +++ b/hw/scsi/megasas.c
> @@ -2348,7 +2348,7 @@ static void megasas_scsi_realize(PCIDevice *dev, Error
> **errp)
> "megasas-queue", 0x40000);
>
> if (megasas_use_msi(s) &&
> - msi_init(dev, 0x50, 1, true, false)) {
> + msi_init(dev, 0x50, 1, true, false) < 0) {
> s->flags &= ~MEGASAS_MASK_USE_MSI;
> }
> if (megasas_use_msix(s) &&
msix_init(dev, 15, &s->mmio_io, b->mmio_bar, 0x2000,
&s->mmio_io, b->mmio_bar, 0x3800, 0x68)) {
s->flags &= ~MEGASAS_MASK_USE_MSIX;
}
This looks like the same bug, but it's actually okay, since msix_init()
returns 0 on success. Suggest to test < 0 anyway so that future readers
don't get misled into thinking there's a bug like I was.
Marcel, this difference between msi_init() and msix_init() is just mean.
Please clean it up.
