scsi: bfa: Fix function pointer type mismatch for hcb_qe->cbfn

Some callback functions used here take a boolean argument, others take a
status argument. This breaks KCFI type checking, so clang now warns about
the function pointer cast:

drivers/scsi/bfa/bfad_bsg.c:2138:29: error: cast from 'void (*)(void *, enum bfa_status)' to 'bfa_cb_cbfn_t' (aka 'void (*)(void *, enum bfa_boolean)') converts to incompatible function type [-Werror,-Wcast-function-type-strict]

Assuming the code is actually correct here and the callers always match the
argument types of the callee, rework this to replace the explicit cast with
a union of the two pointer types. This does not change the behavior of the
code, so if something is actually broken here, a larger rework may be
necessary.

Fixes: 37ea055 ("[SCSI] bfa: Added support to collect and reset fcport stats")
Fixes: 3ec4f2c ("[SCSI] bfa: Added support to configure QOS and collect stats.")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240222124433.2046570-1-arnd@kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: arndb

drivers/scsi/bfa/bfa.h

@@ -20,7 +20,6 @@
 struct bfa_s;
 
 typedef void (*bfa_isr_func_t) (struct bfa_s *bfa, struct bfi_msg_s *m);
-typedef void (*bfa_cb_cbfn_status_t) (void *cbarg, bfa_status_t status);
 
 /*
  * Interrupt message handlers
@@ -437,4 +436,12 @@ struct bfa_cb_pending_q_s {
 	(__qe)->data = (__data);				\
 } while (0)
 
+#define bfa_pending_q_init_status(__qe, __cbfn, __cbarg, __data) do {	\
+	bfa_q_qe_init(&((__qe)->hcb_qe.qe));			\
+	(__qe)->hcb_qe.cbfn_status = (__cbfn);			\
+	(__qe)->hcb_qe.cbarg = (__cbarg);			\
+	(__qe)->hcb_qe.pre_rmv = BFA_TRUE;			\
+	(__qe)->data = (__data);				\
+} while (0)
+
 #endif /* __BFA_H__ */

drivers/scsi/bfa/bfa_core.c

@@ -1907,15 +1907,13 @@ bfa_comp_process(struct bfa_s *bfa, struct list_head *comp_q)
 	struct list_head		*qe;
 	struct list_head		*qen;
 	struct bfa_cb_qe_s	*hcb_qe;
-	bfa_cb_cbfn_status_t	cbfn;
 
 	list_for_each_safe(qe, qen, comp_q) {
 		hcb_qe = (struct bfa_cb_qe_s *) qe;
 		if (hcb_qe->pre_rmv) {
 			/* qe is invalid after return, dequeue before cbfn() */
 			list_del(qe);
-			cbfn = (bfa_cb_cbfn_status_t)(hcb_qe->cbfn);
-			cbfn(hcb_qe->cbarg, hcb_qe->fw_status);
+			hcb_qe->cbfn_status(hcb_qe->cbarg, hcb_qe->fw_status);
 		} else
 			hcb_qe->cbfn(hcb_qe->cbarg, BFA_TRUE);
 	}

drivers/scsi/bfa/bfa_ioc.h

@@ -361,14 +361,18 @@ struct bfa_reqq_wait_s {
 	void	*cbarg;
 };
 
-typedef void	(*bfa_cb_cbfn_t) (void *cbarg, bfa_boolean_t complete);
+typedef void (*bfa_cb_cbfn_t) (void *cbarg, bfa_boolean_t complete);
+typedef void (*bfa_cb_cbfn_status_t) (void *cbarg, bfa_status_t status);
 
 /*
  * Generic BFA callback element.
  */
 struct bfa_cb_qe_s {
 	struct list_head	qe;
-	bfa_cb_cbfn_t	cbfn;
+	union {
+		bfa_cb_cbfn_status_t	cbfn_status;
+		bfa_cb_cbfn_t		cbfn;
+	};
 	bfa_boolean_t	once;
 	bfa_boolean_t	pre_rmv;	/* set for stack based qe(s) */
 	bfa_status_t	fw_status;	/* to access fw status in comp proc */

drivers/scsi/bfa/bfad_bsg.c

@@ -2135,8 +2135,7 @@ bfad_iocmd_fcport_get_stats(struct bfad_s *bfad, void *cmd)
 	struct bfa_cb_pending_q_s cb_qe;
 
 	init_completion(&fcomp.comp);
-	bfa_pending_q_init(&cb_qe, (bfa_cb_cbfn_t)bfad_hcb_comp,
-			   &fcomp, &iocmd->stats);
+	bfa_pending_q_init_status(&cb_qe, bfad_hcb_comp, &fcomp, &iocmd->stats);
 	spin_lock_irqsave(&bfad->bfad_lock, flags);
 	iocmd->status = bfa_fcport_get_stats(&bfad->bfa, &cb_qe);
 	spin_unlock_irqrestore(&bfad->bfad_lock, flags);
@@ -2159,7 +2158,7 @@ bfad_iocmd_fcport_reset_stats(struct bfad_s *bfad, void *cmd)
 	struct bfa_cb_pending_q_s cb_qe;
 
 	init_completion(&fcomp.comp);
-	bfa_pending_q_init(&cb_qe, (bfa_cb_cbfn_t)bfad_hcb_comp, &fcomp, NULL);
+	bfa_pending_q_init_status(&cb_qe, bfad_hcb_comp, &fcomp, NULL);
 
 	spin_lock_irqsave(&bfad->bfad_lock, flags);
 	iocmd->status = bfa_fcport_clear_stats(&bfad->bfa, &cb_qe);
@@ -2443,8 +2442,7 @@ bfad_iocmd_qos_get_stats(struct bfad_s *bfad, void *cmd)
 	struct bfa_fcport_s *fcport = BFA_FCPORT_MOD(&bfad->bfa);
 
 	init_completion(&fcomp.comp);
-	bfa_pending_q_init(&cb_qe, (bfa_cb_cbfn_t)bfad_hcb_comp,
-			   &fcomp, &iocmd->stats);
+	bfa_pending_q_init_status(&cb_qe, bfad_hcb_comp, &fcomp, &iocmd->stats);
 
 	spin_lock_irqsave(&bfad->bfad_lock, flags);
 	WARN_ON(!bfa_ioc_get_fcmode(&bfad->bfa.ioc));
@@ -2474,8 +2472,7 @@ bfad_iocmd_qos_reset_stats(struct bfad_s *bfad, void *cmd)
 	struct bfa_fcport_s *fcport = BFA_FCPORT_MOD(&bfad->bfa);
 
 	init_completion(&fcomp.comp);
-	bfa_pending_q_init(&cb_qe, (bfa_cb_cbfn_t)bfad_hcb_comp,
-			   &fcomp, NULL);
+	bfa_pending_q_init_status(&cb_qe, bfad_hcb_comp, &fcomp, NULL);
 
 	spin_lock_irqsave(&bfad->bfad_lock, flags);
 	WARN_ON(!bfa_ioc_get_fcmode(&bfad->bfa.ioc));