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reduce redundant load_mbuf code
> Date: Tue, 12 Aug 2025 20:55:00 +0200
> From: Jan Klemkow <jan@openbsd.org>
>
> On Tue, Aug 12, 2025 at 08:42:36PM +0200, Claudio Jeker wrote:
> > On Tue, Aug 12, 2025 at 08:39:02PM +0200, Jan Klemkow wrote:
> > > Hi,
> > >
> > > This diff reduces the redundant bus_dmamap_load_mbuf(), m_defrag() and
> > > bus_dmamap_load_mbuf() call chain. In many other interface drivers are
> > > similar implementations with switch/case statements, which could be
> > > reduced with the same function but in a separate diff.
> > >
> > > ok?
> >
> > Please don't do that. The goal is to put m_defrag into
> > bus_dmamap_load_mbuf() and not hide it behind yet another abstraction.
>
> I tried you suggestion first, but bus_dmamap_load_mbuf() is very
> different between the architectures. I could try in small steps, arch
> by arch?! For instance compare amd64 and sparc64. I couldn't get why
> bus_dmamap_load_mbuf() in sparc64 don't just use bus_dmamap_load_buffer().
Because IOMMUs are a bit like magic!
> > > Index: dev/pci/if_iavf.c
> > > ===================================================================
> > > RCS file: /cvs/src/sys/dev/pci/if_iavf.c,v
> > > diff -u -p -r1.25 if_iavf.c
> > > --- dev/pci/if_iavf.c 24 Jun 2025 10:59:15 -0000 1.25
> > > +++ dev/pci/if_iavf.c 12 Aug 2025 17:30:35 -0000
> > > @@ -1915,24 +1915,6 @@ iavf_txr_free(struct iavf_softc *sc, str
> > > free(txr, M_DEVBUF, sizeof(*txr));
> > > }
> > >
> > > -static inline int
> > > -iavf_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > -{
> > > - int error;
> > > -
> > > - error = bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > - if (error != EFBIG)
> > > - return (error);
> > > -
> > > - error = m_defrag(m, M_DONTWAIT);
> > > - if (error != 0)
> > > - return (error);
> > > -
> > > - return (bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > -}
> > > -
> > > static uint64_t
> > > iavf_tx_offload(struct mbuf *m, struct iavf_tx_ring *txr, unsigned int prod)
> > > {
> > > @@ -2072,7 +2054,7 @@ iavf_start(struct ifqueue *ifq)
> > > free--;
> > > }
> > >
> > > - if (iavf_load_mbuf(sc->sc_dmat, map, m) != 0) {
> > > + if (m_load_dmamap(sc->sc_dmat, map, m) != 0) {
> > > ifq->ifq_errors++;
> > > m_freem(m);
> > > continue;
> > > Index: dev/pci/if_ice.c
> > > ===================================================================
> > > RCS file: /cvs/src/sys/dev/pci/if_ice.c,v
> > > diff -u -p -r1.56 if_ice.c
> > > --- dev/pci/if_ice.c 17 Jul 2025 09:19:21 -0000 1.56
> > > +++ dev/pci/if_ice.c 12 Aug 2025 17:07:02 -0000
> > > @@ -13791,24 +13791,6 @@ ice_tx_setup_offload(struct mbuf *m0, st
> > > return offload;
> > > }
> > >
> > > -static inline int
> > > -ice_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > -{
> > > - int error;
> > > -
> > > - error = bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > - if (error != EFBIG)
> > > - return (error);
> > > -
> > > - error = m_defrag(m, M_DONTWAIT);
> > > - if (error != 0)
> > > - return (error);
> > > -
> > > - return (bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > -}
> > > -
> > > void
> > > ice_set_tso_context(struct mbuf *m0, struct ice_tx_queue *txq,
> > > unsigned int prod, struct ether_extracted *ext)
> > > @@ -13905,7 +13887,7 @@ ice_start(struct ifqueue *ifq)
> > > txm = &txq->tx_map[prod];
> > > map = txm->txm_map;
> > >
> > > - if (ice_load_mbuf(sc->sc_dmat, map, m) != 0) {
> > > + if (m_load_dmamap(sc->sc_dmat, map, m) != 0) {
> > > ifq->ifq_errors++;
> > > m_freem(m);
> > > continue;
> > > Index: dev/pci/if_igc.c
> > > ===================================================================
> > > RCS file: /cvs/src/sys/dev/pci/if_igc.c,v
> > > diff -u -p -r1.28 if_igc.c
> > > --- dev/pci/if_igc.c 24 Jun 2025 11:00:27 -0000 1.28
> > > +++ dev/pci/if_igc.c 12 Aug 2025 17:08:18 -0000
> > > @@ -937,24 +937,6 @@ igc_init(void *arg)
> > > splx(s);
> > > }
> > >
> > > -static inline int
> > > -igc_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > -{
> > > - int error;
> > > -
> > > - error = bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > - if (error != EFBIG)
> > > - return (error);
> > > -
> > > - error = m_defrag(m, M_DONTWAIT);
> > > - if (error != 0)
> > > - return (error);
> > > -
> > > - return (bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > -}
> > > -
> > > void
> > > igc_start(struct ifqueue *ifq)
> > > {
> > > @@ -1003,7 +985,7 @@ igc_start(struct ifqueue *ifq)
> > > txbuf = &txr->tx_buffers[prod];
> > > map = txbuf->map;
> > >
> > > - if (igc_load_mbuf(txr->txdma.dma_tag, map, m) != 0) {
> > > + if (m_load_dmamap(txr->txdma.dma_tag, map, m) != 0) {
> > > ifq->ifq_errors++;
> > > m_freem(m);
> > > continue;
> > > Index: dev/pci/if_ixl.c
> > > ===================================================================
> > > RCS file: /cvs/src/sys/dev/pci/if_ixl.c,v
> > > diff -u -p -r1.108 if_ixl.c
> > > --- dev/pci/if_ixl.c 24 Jun 2025 11:03:10 -0000 1.108
> > > +++ dev/pci/if_ixl.c 12 Aug 2025 17:06:16 -0000
> > > @@ -2746,24 +2746,6 @@ ixl_txr_free(struct ixl_softc *sc, struc
> > > free(txr, M_DEVBUF, sizeof(*txr));
> > > }
> > >
> > > -static inline int
> > > -ixl_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > -{
> > > - int error;
> > > -
> > > - error = bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > - if (error != EFBIG)
> > > - return (error);
> > > -
> > > - error = m_defrag(m, M_DONTWAIT);
> > > - if (error != 0)
> > > - return (error);
> > > -
> > > - return (bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > -}
> > > -
> > > static uint64_t
> > > ixl_tx_setup_offload(struct mbuf *m0, struct ixl_tx_ring *txr,
> > > unsigned int prod)
> > > @@ -2905,7 +2887,7 @@ ixl_start(struct ifqueue *ifq)
> > > free--;
> > > }
> > >
> > > - if (ixl_load_mbuf(sc->sc_dmat, map, m) != 0) {
> > > + if (m_load_dmamap(sc->sc_dmat, map, m) != 0) {
> > > ifq->ifq_errors++;
> > > m_freem(m);
> > > continue;
> > > Index: dev/pci/if_vmx.c
> > > ===================================================================
> > > RCS file: /cvs/src/sys/dev/pci/if_vmx.c,v
> > > diff -u -p -r1.93 if_vmx.c
> > > --- dev/pci/if_vmx.c 19 Jun 2025 09:36:21 -0000 1.93
> > > +++ dev/pci/if_vmx.c 12 Aug 2025 17:07:26 -0000
> > > @@ -1535,24 +1535,6 @@ vmxnet3_ioctl(struct ifnet *ifp, u_long
> > > return error;
> > > }
> > >
> > > -static inline int
> > > -vmx_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > -{
> > > - int error;
> > > -
> > > - error = bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > - if (error != EFBIG)
> > > - return (error);
> > > -
> > > - error = m_defrag(m, M_DONTWAIT);
> > > - if (error != 0)
> > > - return (error);
> > > -
> > > - return (bus_dmamap_load_mbuf(dmat, map, m,
> > > - BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > -}
> > > -
> > > void
> > > vmxnet3_tx_offload(struct vmxnet3_txdesc *sop, struct mbuf *m)
> > > {
> > > @@ -1695,7 +1677,7 @@ vmxnet3_start(struct ifqueue *ifq)
> > >
> > > map = ring->dmap[prod];
> > >
> > > - if (vmx_load_mbuf(sc->sc_dmat, map, m) != 0) {
> > > + if (m_load_dmamap(sc->sc_dmat, map, m) != 0) {
> > > ifq->ifq_errors++;
> > > m_freem(m);
> > > continue;
> > > Index: sys/mbuf.h
> > > ===================================================================
> > > RCS file: /cvs/src/sys/sys/mbuf.h,v
> > > diff -u -p -r1.267 mbuf.h
> > > --- sys/mbuf.h 25 Jun 2025 20:26:32 -0000 1.267
> > > +++ sys/mbuf.h 12 Aug 2025 17:10:52 -0000
> > > @@ -35,6 +35,7 @@
> > > #ifndef _SYS_MBUF_H_
> > > #define _SYS_MBUF_H_
> > >
> > > +#include <machine/bus.h>
> > > #include <sys/queue.h>
> > >
> > > /*
> > > @@ -464,6 +465,24 @@ m_freemp(struct mbuf **mp)
> > >
> > > *mp = NULL;
> > > return m_freem(m);
> > > +}
> > > +
> > > +static inline int
> > > +m_load_dmamap(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m)
> > > +{
> > > + int error;
> > > +
> > > + error = bus_dmamap_load_mbuf(dmat, map, m,
> > > + BUS_DMA_STREAMING | BUS_DMA_NOWAIT);
> > > + if (error != EFBIG)
> > > + return (error);
> > > +
> > > + error = m_defrag(m, M_DONTWAIT);
> > > + if (error != 0)
> > > + return (error);
> > > +
> > > + return (bus_dmamap_load_mbuf(dmat, map, m,
> > > + BUS_DMA_STREAMING | BUS_DMA_NOWAIT));
> > > }
> > >
> > > #include <sys/percpu.h>
> > >
> >
> > --
> > :wq Claudio
> >
>
>
reduce redundant load_mbuf code