bnx2x_sriov.c: Missing switch/case breaks?

bnx2x_sriov.c: Missing switch/case breaks?

[Joe Perches]

Hi Ariel.

I wrote a little checkpatch script to look for missing
switch/case breaks.

http://www.kernelhub.org/?msg=379933&p=2

There are _many_ instances of case blocks in sriov.c
that could be missing breaks as they use fall-throughs.

It would be good if these are actually intended to be
fall-throughs to add a /* fall-through */ comment between
each case block.

For instance:

static void bnx2x_vfop_qctor(struct bnx2x *bp, struct bnx2x_virtf *vf)
{
[...]
	switch (state) {
	case BNX2X_VFOP_QCTOR_INIT:

		/* has this queue already been opened? */
		if (bnx2x_get_q_logical_state(bp, q_params->q_obj) ==
		    BNX2X_Q_LOGICAL_STATE_ACTIVE) {
			DP(BNX2X_MSG_IOV,
			   "Entered qctor but queue was already up. Aborting gracefully\n");
			goto op_done;
		}

		/* next state */
		vfop->state = BNX2X_VFOP_QCTOR_SETUP;

		q_params->cmd = BNX2X_Q_CMD_INIT;
		vfop->rc = bnx2x_queue_state_change(bp, q_params);

		bnx2x_vfop_finalize(vf, vfop->rc, VFOP_CONT);

	case BNX2X_VFOP_QCTOR_SETUP:
		/* next state */
		vfop->state = BNX2X_VFOP_QCTOR_INT_EN;

		/* copy pre-prepared setup params to the queue-state params */
		vfop->op_p->qctor.qstate.params.setup =
			vfop->op_p->qctor.prep_qsetup;

		q_params->cmd = BNX2X_Q_CMD_SETUP;
		vfop->rc = bnx2x_queue_state_change(bp, q_params);

		bnx2x_vfop_finalize(vf, vfop->rc, VFOP_CONT);

---

Here's the checkpatch output on that file

$ ./scripts/checkpatch.pl -f --types=missing_break drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#326: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:326:
+	case BNX2X_VFOP_QCTOR_SETUP:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#339: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:339:
+	case BNX2X_VFOP_QCTOR_INT_EN:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#416: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:416:
+	case BNX2X_VFOP_QDTOR_TERMINATE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#425: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:425:
+	case BNX2X_VFOP_QDTOR_CFCDEL:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#437: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:437:
+	case BNX2X_VFOP_QDTOR_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#622: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:622:
+	case BNX2X_VFOP_VLAN_MAC_CONFIG_SINGLE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#633: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:633:
+	case BNX2X_VFOP_VLAN_MAC_CHK_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#637: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:637:
+	case BNX2X_VFOP_MAC_CONFIG_LIST:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#650: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:650:
+	case BNX2X_VFOP_VLAN_CONFIG_LIST:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#662: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:662:
+	default:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#971: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:971:
+	case BNX2X_VFOP_QSETUP_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1068: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1068:
+	case BNX2X_VFOP_QFLR_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1119: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1119:
+	case BNX2X_VFOP_MCAST_ADD:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1136: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1136:
+	case BNX2X_VFOP_MCAST_CHK_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1139: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1139:
+	default:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1217: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1217:
+	case BNX2X_VFOP_RXMODE_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#1326: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:1326:
+	case BNX2X_VFOP_QTEARDOWN_DONE:

WARNING: Possible switch case/default not preceeded by break or fallthrough comment
#2985: FILE: drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c:2985:
+	case BNX2X_VFOP_RSS_DONE:

total: 0 errors, 18 warnings, 3683 lines checked

NOTE: Used message types: MISSING_BREAK

drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c has style problems, please review.

If any of these errors are false positives, please report
them to the maintainer, see CHECKPATCH in MAINTAINERS.
total: 0 errors, 0 warnings, 2006 lines checked

NOTE: Used message types: MISSING_BREAK

RE: bnx2x_sriov.c: Missing switch/case breaks?

[Yuval Mintz]

> Hi Ariel.
> 
> I wrote a little checkpatch script to look for missing
> switch/case breaks.
> 
> http://www.kernelhub.org/?msg=379933&p=2
> 
> There are _many_ instances of case blocks in sriov.c
> that could be missing breaks as they use fall-throughs.
> 
> It would be good if these are actually intended to be
> fall-throughs to add a /* fall-through */ comment between
> each case block.
> 
> For instance:
> 
> static void bnx2x_vfop_qctor(struct bnx2x *bp, struct bnx2x_virtf *vf)
> {
> [...]
> 	switch (state) {
> 	case BNX2X_VFOP_QCTOR_INIT:
> 
> 		/* has this queue already been opened? */
> 		if (bnx2x_get_q_logical_state(bp, q_params->q_obj) ==
> 		    BNX2X_Q_LOGICAL_STATE_ACTIVE) {
> 			DP(BNX2X_MSG_IOV,
> 			   "Entered qctor but queue was already up. Aborting
> gracefully\n");
> 			goto op_done;
> 		}
> 
> 		/* next state */
> 		vfop->state = BNX2X_VFOP_QCTOR_SETUP;
> 
> 		q_params->cmd = BNX2X_Q_CMD_INIT;
> 		vfop->rc = bnx2x_queue_state_change(bp, q_params);
> 
> 		bnx2x_vfop_finalize(vf, vfop->rc, VFOP_CONT); 

Hi Joe,

The `vfop' part of the code contains a lot of usage of the `bnx2x_vfop_finalize()',
which either goto or return at the end of almost every case.
"Normal" analysis tools/scripts fail to recognize them as  valid case breaks.

Adding `fallthrough' comments would make little sense, as this is not the real
behavior; Perhaps we need some alternative comment? (something in the line
of `macro case break')

Cheers,
Yuval

Re: bnx2x_sriov.c: Missing switch/case breaks?

[Joe Perches]

On Sat, 2013-12-14 at 06:16 +0000, Yuval Mintz wrote:
> > Hi Ariel.
> > 
> > I wrote a little checkpatch script to look for missing
> > switch/case breaks.
> > 
> > http://www.kernelhub.org/?msg=379933&p=2
> > 
> > There are _many_ instances of case blocks in sriov.c
> > that could be missing breaks as they use fall-throughs.
> > 
> > It would be good if these are actually intended to be
> > fall-throughs to add a /* fall-through */ comment between
> > each case block.
> > 
> > For instance:
> > 
> > static void bnx2x_vfop_qctor(struct bnx2x *bp, struct bnx2x_virtf *vf)
> > {
> > [...]
> > 	switch (state) {
> > 	case BNX2X_VFOP_QCTOR_INIT:
> > 
> > 		/* has this queue already been opened? */
> > 		if (bnx2x_get_q_logical_state(bp, q_params->q_obj) ==
> > 		    BNX2X_Q_LOGICAL_STATE_ACTIVE) {
> > 			DP(BNX2X_MSG_IOV,
> > 			   "Entered qctor but queue was already up. Aborting
> > gracefully\n");
> > 			goto op_done;
> > 		}
> > 
> > 		/* next state */
> > 		vfop->state = BNX2X_VFOP_QCTOR_SETUP;
> > 
> > 		q_params->cmd = BNX2X_Q_CMD_INIT;
> > 		vfop->rc = bnx2x_queue_state_change(bp, q_params);
> > 
> > 		bnx2x_vfop_finalize(vf, vfop->rc, VFOP_CONT); 
> 
> Hi Joe,

Hi Yuval.

> The `vfop' part of the code contains a lot of usage of the `bnx2x_vfop_finalize()',
> which either goto or return at the end of almost every case.
> "Normal" analysis tools/scripts fail to recognize them as  valid case breaks.
> 
> Adding `fallthrough' comments would make little sense, as this is not the real
> behavior; Perhaps we need some alternative comment? (something in the line
> of `macro case break')

No idea.  It's certainly an ugly macro.

This does have a fallthrough path though when
(rc == 0  && next == VFOP_VERIFY_PEND) so
maybe there should be a break after most all
uses of this macro anyway.  When next is
VFOP_VERIFY_PEND, then a "fall-through" comment
would be appropriate.

cheers, Joe

drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h:#define bnx2x_vfop_finalize(vf, rc, next) do {                                \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              if ((rc) < 0)                                           \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      goto op_err;                                    \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              else if ((rc) > 0)                                      \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      goto op_pending;                                \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              else if ((next) == VFOP_DONE)                           \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      goto op_done;                                   \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              else if ((next) == VFOP_VERIFY_PEND)                    \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      BNX2X_ERR("expected pending\n");                \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              else {                                                  \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      DP(BNX2X_MSG_IOV, "no ramrod. Scheduling\n");   \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      atomic_set(&vf->op_in_progress, 1);             \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      queue_delayed_work(bnx2x_wq, &bp->sp_task, 0);  \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-                      return;                                         \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-              }                                                       \
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-      } while (0)
drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.h-

RE: bnx2x_sriov.c: Missing switch/case breaks?

[Yuval Mintz]

> > > Hi Ariel.
> > >
> > > I wrote a little checkpatch script to look for missing
> > > switch/case breaks.
> > >
> > > http://www.kernelhub.org/?msg=379933&p=2
> > >
> > > There are _many_ instances of case blocks in sriov.c
> > > that could be missing breaks as they use fall-throughs.
> > >
> > > It would be good if these are actually intended to be
> > > fall-throughs to add a /* fall-through */ comment between
> > > each case block.
> > >
> > Hi Joe,
> 
> Hi Yuval.
> 
> > The `vfop' part of the code contains a lot of usage of the
> `bnx2x_vfop_finalize()',
> > which either goto or return at the end of almost every case.
> > "Normal" analysis tools/scripts fail to recognize them as  valid case
> breaks.
> >
> > Adding `fallthrough' comments would make little sense, as this is not the
> real
> > behavior; Perhaps we need some alternative comment? (something in the
> line
> > of `macro case break')
> 
> No idea.  It's certainly an ugly macro.
> 

True.

> This does have a fallthrough path though when
> (rc == 0  && next == VFOP_VERIFY_PEND) so

This is a very rare path - there's exactly one place in the bnx2x code
Where `next == VFOP_VERIFY_PEND' (also notice this path prints an
error, so this is obviously not the expected behaviour).

> maybe there should be a break after most all
> uses of this macro anyway.  When next is

Won't some static code analysis tools regard such `break' calls as
unreachable code?

> VFOP_VERIFY_PEND, then a "fall-through" comment
> would be appropriate.
> 
> cheers, Joe

Thanks,
Yuval

Re: bnx2x_sriov.c: Missing switch/case breaks?

[Joe Perches]

On Sat, 2013-12-14 at 13:26 +0000, Yuval Mintz wrote:
> > > The `vfop' part of the code contains a lot of usage of the
> > `bnx2x_vfop_finalize()',
> > > which either goto or return at the end of almost every case.
> > > "Normal" analysis tools/scripts fail to recognize them as  valid case
> > breaks.
> > >
> > > Adding `fallthrough' comments would make little sense, as this is not the
> > real
> > > behavior; Perhaps we need some alternative comment? (something in the
> > line
> > > of `macro case break')
> > 
> > No idea.  It's certainly an ugly macro.
> > 
> 
> True.
[]
> > maybe there should be a break after most all
> > uses of this macro anyway.  When next is
> 
> Won't some static code analysis tools regard such `break' calls as
> unreachable code?

I suppose that maybe true,
but this could also work...

		bnx2x_vfop_finalize(vf, vfop->rc, VFOP_CONT); 
				/* Ugly goto|return macro, not fall-through */

;)