Using common code for csiostor.

Using common code for csiostor.

[Praveen Madhavan]

Hi Christoph,
csiostor is chelsio full offload FCoE physical function driver. I would like to reuse common hardware interface functions defined in t4_hw.c of chelsio networking driver(cxgb4). Below is makefile change that creates softlink to t4_hw.c and builds the same. Is this change is acceptable? Please suggest if there is any better way of doing this.

diff --git a/drivers/scsi/csiostor/Makefile b/drivers/scsi/csiostor/Makefile
index 913b9a9..74117f3 100644
--- a/drivers/scsi/csiostor/Makefile
+++ b/drivers/scsi/csiostor/Makefile
@@ -5,8 +5,9 @@

 ccflags-y += -I$(srctree)/drivers/net/ethernet/chelsio/cxgb4

 obj-$(CONFIG_SCSI_CHELSIO_FCOE) := csiostor.o
 csiostor-objs := csio_attr.o csio_init.o csio_lnode.o csio_scsi.o \
                csio_hw.o csio_hw_t4.o csio_hw_t5.o csio_isr.o \
-               csio_mb.o csio_rnode.o csio_wr.o
+               csio_mb.o csio_rnode.o csio_wr.o t4_hw.o
+$(obj)/t4_hw.c:
+       ln -sf $(srctree)/drivers/net/ethernet/chelsio/cxgb4/t4_hw.c $(obj)/t4_hw.c

Re: Using common code for csiostor.

[James Bottomley]

On Wed, 2014-12-17 at 15:51 +0000, Praveen Madhavan wrote:
> Hi Christoph,
> csiostor is chelsio full offload FCoE physical function driver. I
> would like to reuse common hardware interface functions defined in
> t4_hw.c of chelsio networking driver(cxgb4). Below is makefile change
> that creates softlink to t4_hw.c and builds the same. Is this change
> is acceptable? Please suggest if there is any better way of doing
> this.

The usual way to do this is to make the common hardware function a base
module and make all drivers that use it depend on it.  Like iwldvm ->
iwlwifi -> mac80211 etc.

We really wouldn't want to do the link and build because that will
create two identical binary copies of the interface (one in SCSI and one
in net) which is a waste of text space.

James

Re: Using common code for csiostor.

[hch]

On Wed, Dec 17, 2014 at 08:10:15AM -0800, James Bottomley wrote:
> The usual way to do this is to make the common hardware function a base
> module and make all drivers that use it depend on it.  Like iwldvm ->
> iwlwifi -> mac80211 etc.
> 
> We really wouldn't want to do the link and build because that will
> create two identical binary copies of the interface (one in SCSI and one
> in net) which is a waste of text space.

Agreed.  If the amount of shared code is really small a header with
inlines might be an alternative as there is some overhead creating a new
module.