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SubjectRe: [PATCH RFC v2] fcoe: make use of fip_mode enum complete
On Mon, Feb 11, 2019 at 6:53 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Mon, Feb 11, 2019 at 06:07:51PM +0100, Sedat Dilek wrote:
> > From: Sedat Dilek <sedat.dilek@gmail.com>
> >
> > commit 1917d42d14b7 ("fcoe: use enum for fip_mode") introduces a separate
> > enum for the fip_mode that shall be used during initialisation handling
> > until it is passed to fcoe_ctrl_link_up to set the initial fip_state.
> > That change was incomplete and gcc quietly converted in various places
> > between the fip_mode and the fip_state enum values with implicit enum
> > conversions, which fortunately cannot cause any issues in the actual
> > code's execution.
> >
> > clang however warns about these implicit enum conversions in the scsi
> > drivers. This commit consolidates the use of the two enums, guided by
> > clang's enum-conversion warnings.
> >
> > This commit now completes the use of the fip_mode:
> > It expects and uses fip_mode in {bnx2fc,fcoe}_interface_create and
> > fcoe_ctlr_init, and it explicitly converts from fip_mode to fip_state
> > only at the single point in fcoe_ctlr_link_up.
> >
> > To eliminate that adding or removing values from fip_mode or fip_state enum
> > break the right mapping of values, all fip_mode values are assigned to
> > their fip_state counterparts.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/151
> > Fixes: 1917d42d14b7 ("fcoe: use enum for fip_mode")
> > Reported-by: Dmitry Golovin "Twisted Pair in my Hair" <dima@golovin.in>
> > CC: Lukas Bulwahn <lukas.bulwahn@gmail.com>
> > CC: Nick Desaulniers <ndesaulniers@google.com>
> > CC: Nathan Chancellor <natechancellor@gmail.com>
> > CC: Hannes Reinecke <hare@suse.com>
> > Suggested-by: Johannes Thumshirn <jthumshirn@suse.de>
> > ---
> >
> > [ v2:
> > - Based on the original patch by Lukas Bulwahn
> > - Suggestion by Johannes T. [1] required some changes:
> > + s/case FIP_ST_VMMP_START/case FIP_ST_V*N*MP_START
> > + s/return FIP_ST_AUTO/return FIP_MODE_AUTO
> > - Add Link to ClangBuiltLinux issue #151
> > - S-o-b line later when there is an OK from the FCoE maintainers
> >
> > NOTE: Compile-tested against Linux-v5.0-rc6 with LLVM/Clang from Git with
> > experimental asm-goto support via executing:
> > $ make V=1 CC=clang-9 HOSTCC=clang-9 drivers/scsi/fcoe/
> >
> > [1] https://marc.info/?l=linux-scsi&m=154745527612152&w=2
> >
> > -dileks ]
> >
> > drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 2 +-
> > drivers/scsi/fcoe/fcoe.c | 2 +-
> > drivers/scsi/fcoe/fcoe_ctlr.c | 4 ++--
> > drivers/scsi/fcoe/fcoe_transport.c | 2 +-
> > drivers/scsi/qedf/qedf_main.c | 2 +-
> > include/scsi/libfcoe.h | 22 ++++++++++++++++++++--
> > 6 files changed, 26 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> > index 2e4e7159ebf9..a75e74ad1698 100644
> > --- a/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> > +++ b/drivers/scsi/bnx2fc/bnx2fc_fcoe.c
> > @@ -1438,7 +1438,7 @@ static struct bnx2fc_hba *bnx2fc_hba_create(struct cnic_dev *cnic)
> > static struct bnx2fc_interface *
> > bnx2fc_interface_create(struct bnx2fc_hba *hba,
> > struct net_device *netdev,
> > - enum fip_state fip_mode)
> > + enum fip_mode fip_mode)
> > {
> > struct fcoe_ctlr_device *ctlr_dev;
> > struct bnx2fc_interface *interface;
> > diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
> > index cd19be3f3405..8ba8862d3292 100644
> > --- a/drivers/scsi/fcoe/fcoe.c
> > +++ b/drivers/scsi/fcoe/fcoe.c
> > @@ -389,7 +389,7 @@ static int fcoe_interface_setup(struct fcoe_interface *fcoe,
> > * Returns: pointer to a struct fcoe_interface or NULL on error
> > */
> > static struct fcoe_interface *fcoe_interface_create(struct net_device *netdev,
> > - enum fip_state fip_mode)
> > + enum fip_mode fip_mode)
> > {
> > struct fcoe_ctlr_device *ctlr_dev;
> > struct fcoe_ctlr *ctlr;
> > diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
> > index 54da3166da8d..a52d3ad94876 100644
> > --- a/drivers/scsi/fcoe/fcoe_ctlr.c
> > +++ b/drivers/scsi/fcoe/fcoe_ctlr.c
> > @@ -147,7 +147,7 @@ static void fcoe_ctlr_map_dest(struct fcoe_ctlr *fip)
> > * fcoe_ctlr_init() - Initialize the FCoE Controller instance
> > * @fip: The FCoE controller to initialize
> > */
> > -void fcoe_ctlr_init(struct fcoe_ctlr *fip, enum fip_state mode)
> > +void fcoe_ctlr_init(struct fcoe_ctlr *fip, enum fip_mode mode)
> > {
> > fcoe_ctlr_set_state(fip, FIP_ST_LINK_WAIT);
> > fip->mode = mode;
> > @@ -454,7 +454,7 @@ void fcoe_ctlr_link_up(struct fcoe_ctlr *fip)
> > mutex_unlock(&fip->ctlr_mutex);
> > fc_linkup(fip->lp);
> > } else if (fip->state == FIP_ST_LINK_WAIT) {
> > - fcoe_ctlr_set_state(fip, fip->mode);
> > + fcoe_ctlr_set_state(fip, (enum fip_state) fip->mode);
> > switch (fip->mode) {
> > default:
> > LIBFCOE_FIP_DBG(fip, "invalid mode %d\n", fip->mode);
> > diff --git a/drivers/scsi/fcoe/fcoe_transport.c b/drivers/scsi/fcoe/fcoe_transport.c
> > index f4909cd206d3..b381ab066b9c 100644
> > --- a/drivers/scsi/fcoe/fcoe_transport.c
> > +++ b/drivers/scsi/fcoe/fcoe_transport.c
> > @@ -873,7 +873,7 @@ static int fcoe_transport_create(const char *buffer,
> > int rc = -ENODEV;
> > struct net_device *netdev = NULL;
> > struct fcoe_transport *ft = NULL;
> > - enum fip_state fip_mode = (enum fip_state)(long)kp->arg;
> > + enum fip_mode fip_mode = (enum fip_mode)(long)kp->arg;
> >
> > mutex_lock(&ft_mutex);
> >
> > diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
> > index 9bbc19fc190b..9f9431a4cc0e 100644
> > --- a/drivers/scsi/qedf/qedf_main.c
> > +++ b/drivers/scsi/qedf/qedf_main.c
> > @@ -1418,7 +1418,7 @@ static struct libfc_function_template qedf_lport_template = {
> >
> > static void qedf_fcoe_ctlr_setup(struct qedf_ctx *qedf)
> > {
> > - fcoe_ctlr_init(&qedf->ctlr, FIP_ST_AUTO);
> > + fcoe_ctlr_init(&qedf->ctlr, FIP_MODE_AUTO);
> >
> > qedf->ctlr.send = qedf_fip_send;
> > qedf->ctlr.get_src_addr = qedf_get_src_mac;
> > diff --git a/include/scsi/libfcoe.h b/include/scsi/libfcoe.h
> > index cb8a273732cf..38bb5b798a81 100644
> > --- a/include/scsi/libfcoe.h
> > +++ b/include/scsi/libfcoe.h
> > @@ -79,12 +79,30 @@ enum fip_state {
> > * It must not change after fcoe_ctlr_init() sets it.
> > */
> > enum fip_mode {
> > - FIP_MODE_AUTO = FIP_ST_AUTO,
> > + FIP_MODE_AUTO,
> > FIP_MODE_NON_FIP,
> > FIP_MODE_FABRIC,
> > FIP_MODE_VN2VN,
> > };
> >
> > +static inline enum fip_mode fip_state_to_mode(enum fip_state state)
>
> Hi Sedat,
>
> You added this function but you didn't use it anywhere. I think Johannes
> wanted this function to be used instead of all of the places where
> you/Lukas changed the cast or raw enum value so that the conversion
> still happens but it's explicit.
>
> I think we'll need two versions of this function, one that goes from
> state to mode and another that goes from mode to state as both
> conversions happen (x86 allyesconfig build in drivers/scsi/):
>
> drivers/scsi/fcoe/fcoe.c:2225:39: warning: implicit conversion from enumeration type 'enum fip_mode' to different enumeration type 'enum fip_state' [-Wenum-conversion]
> drivers/scsi/bnx2fc/bnx2fc_fcoe.c:2363:51: warning: implicit conversion from enumeration type 'enum fip_mode' to different enumeration type 'enum fip_state' [-Wenum-conversion]
> drivers/scsi/fnic/fnic_main.c:774:31: warning: implicit conversion from enumeration type 'enum fip_mode' to different enumeration type 'enum fip_state' [-Wenum-conversion]
> drivers/scsi/fnic/fnic_main.c:785:31: warning: implicit conversion from enumeration type 'enum fip_mode' to different enumeration type 'enum fip_state' [-Wenum-conversion]
> drivers/scsi/fcoe/fcoe_ctlr.c:153:14: warning: implicit conversion from enumeration type 'enum fip_state' to different enumeration type 'enum fip_mode' [-Wenum-conversion]
> drivers/scsi/fcoe/fcoe_ctlr.c:457:33: warning: implicit conversion from enumeration type 'enum fip_mode' to different enumeration type 'enum fip_state' [-Wenum-conversion]
>
> Let me know what you think,
> Nathan
>

Hi Nathan,

Thanks for your review.

I have no experience with FCoE (just googled "Fibre Channel over
Ethernet") and its states and modes and what a "fip_mode_to_state()"
will require.

How did you see these -Wenum-conversion warnings - by using the
suggested "static inline enum" (fip_state_to_mode()) line?

Let us see what the FCoE maintaineres suggest.

Regards,
- Sedat -

> > +{
> > + switch (state) {
> > + case FIP_ST_AUTO:
> > + return FIP_MODE_AUTO;
> > + case FIP_ST_NON_FIP:
> > + return FIP_MODE_NON_FIP;
> > + case FIP_ST_ENABLED:
> > + return FIP_MODE_FABRIC;
> > + case FIP_ST_VNMP_START:
> > + return FIP_MODE_VN2VN;
> > + default:
> > + WARN(1, "Invalid FIP state");
> > + }
> > +
> > + return FIP_MODE_AUTO;
> > +}
> > +
> > /**
> > * struct fcoe_ctlr - FCoE Controller and FIP state
> > * @state: internal FIP state for network link and FIP or non-FIP mode.
> > @@ -250,7 +268,7 @@ struct fcoe_rport {
> > };
> >
> > /* FIP API functions */
> > -void fcoe_ctlr_init(struct fcoe_ctlr *, enum fip_state);
> > +void fcoe_ctlr_init(struct fcoe_ctlr *, enum fip_mode);
> > void fcoe_ctlr_destroy(struct fcoe_ctlr *);
> > void fcoe_ctlr_link_up(struct fcoe_ctlr *);
> > int fcoe_ctlr_link_down(struct fcoe_ctlr *);
> > --
> > 2.20.1
> >

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