Date: Fri, 04 Oct 2013 10:01:12 -0700 From: Sean Bruno <sean_bruno@yahoo.com> To: sbruno@freebsd.org Cc: "FreeBSD-scsi@freebsd.org" <FreeBSD-scsi@freebsd.org> Subject: Re: pci_alloc_msi is always called, is this bad? [never mind] Message-ID: <1380906072.2915.2.camel@localhost> In-Reply-To: <1380902209.2621.11.camel@localhost> References: <CAFMmRNzWwxe=YVJcC7Lkjqru5eugciwzEQHjgE-Bh-ctOykVNQ@mail.gmail.com> <20131003194704.GG41229@kib.kiev.ua> <1380902209.2621.11.camel@localhost>
next in thread | previous in thread | raw e-mail | index | archive | help
--=-PoqG66kFQ3mtexPQW068
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
On Fri, 2013-10-04 at 08:56 -0700, Sean Bruno wrote:
> I was looking at the recent thread on -stable about mfi(4) and I noted
> that it appears, if I'm not mistaken, mfi_pci.c::pci_alloc_msi() is
> *always* invoked regardless of the mfi_msi tuneable. We just ignore the
> allocated MSI by not setting sc->mfi_irq_rid. Is that harmful?
>=20
> ------------------------------------------------------------------------
> 240 /* Allocate IRQ resource. */
> 241 sc->mfi_irq_rid =3D 0;
> 242 count =3D 1;
> 243 if (mfi_msi && pci_alloc_msi(sc->mfi_dev, &count) =3D=3D 0) {
> 244 device_printf(sc->mfi_dev, "Using MSI\n");
> 245 sc->mfi_irq_rid =3D 1;
> 246 }
>=20
>=20
> ------------------------------------------------------------------------
> I would have thought that this would be more correct, avoid calling
> pci_alloc_msi() if mfi_msi isn't set in the first place.
> ------------------------------------------------------------------------
> sc->mfi_irq_ird =3D 0;
> count =3D 1;
> ret =3D 0
> if(mfi_msi)
> ret =3D pci_alloc_msi(sc->mfi_dev, &count);
>=20
> if (!ret) {
> device_printf(sc->mfi_dev, "Using MSI\n");
> sc->mfi_irq_rid =3D 1;
> }
> ------------------------------------------------------------------------
>=20
> Sean
Ah, ok. so, no, this is just me not understanding C. Wrote a small
test to see what kib and scott were chatting about and the conditional
&& does indeed short circuit if the first condition is false. Good to
know. Carry on!
#include <stdio.h>
#include <stdlib.h>
int test()
{
int j =3D 1;
printf ("test is running\n");
return j;
}
int main (int argc, char **argv)
{
int i =3D atoi(argv[1]);
printf ("i %d\n", i);
if ( i && test() )
printf ("both are true\n");
return 0;
}
--=-PoqG66kFQ3mtexPQW068
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: This is a digitally signed message part
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.14 (FreeBSD)
iQEcBAABAgAGBQJSTvRQAAoJEBkJRdwI6BaHSrsH/2r6sTKIXqVoohlSFScWLWvT
75vDpTN0y0IkM8TtbmSUombaIt8M6GTaKumruaWFUgCUDIhz3OveytdckN/zCO1S
rmxnyCrCvYr/ttfoGHz5SOURSPbfeZM5PX4CiiRgjsgwOa8+mFfVqQVs5RbB5nwB
/sYbfvdnP5m9rNVSXOuXv3lJ5LyORoxkxT0vUfOF8fsymrsMB/IcsS4kP2tFWjT5
nNRZLZHIyKH+WoIi+uF7GuQia2nb1LVNrCRw3zL5zL1cBAwT0MHTTlCleMz8nibU
yt+qKu0xI3iCvb1m5Y6C3HopS86oPkdFBUdDkmTCiZXLSJOLmluNNOdeXPQvyrI=
=kr8+
-----END PGP SIGNATURE-----
--=-PoqG66kFQ3mtexPQW068--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?1380906072.2915.2.camel>