powerpc/kprobes: Remove redundant code

At the time being we have something like

	if (something) {
		p = get();
		if (p) {
			if (something_wrong)
				goto out;
			...
			return;
		} else if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}
	p = get();
	if (!p) {
		if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}

This is similar to

	p = get();
	if (!p) {
		if (a != b) {
			if (some_error)
				goto out;
			...
		}
		goto out;
	}
	if (something) {
		if (something_wrong)
			goto out;
		...
		return;
	}
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Reflow the comment that was moved]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/07a17425743600460ce35fa9432d42487a825583.1582099499.git.christophe.leroy@c-s.fr

arch/powerpc/kernel/kprobes.c

@@ -271,23 +271,45 @@ int kprobe_handler(struct pt_regs *regs)
 	preempt_disable();
 	kcb = get_kprobe_ctlblk();
 
+	p = get_kprobe(addr);
+	if (!p) {
+		if (*addr != BREAKPOINT_INSTRUCTION) {
+			/*
+			 * PowerPC has multiple variants of the "trap"
+			 * instruction. If the current instruction is a
+			 * trap variant, it could belong to someone else
+			 */
+			kprobe_opcode_t cur_insn = *addr;
+			if (is_trap(cur_insn))
+				goto no_kprobe;
+			/*
+			 * The breakpoint instruction was removed right
+			 * after we hit it.  Another cpu has removed
+			 * either a probepoint or a debugger breakpoint
+			 * at this address.  In either case, no further
+			 * handling of this interrupt is appropriate.
+			 */
+			ret = 1;
+		}
+		/* Not one of ours: let kernel handle it */
+		goto no_kprobe;
+	}
+
 	/* Check we're not actually recursing */
 	if (kprobe_running()) {
-		p = get_kprobe(addr);
-		if (p) {
 		kprobe_opcode_t insn = *p->ainsn.insn;
-			if (kcb->kprobe_status == KPROBE_HIT_SS &&
-					is_trap(insn)) {
+		if (kcb->kprobe_status == KPROBE_HIT_SS && is_trap(insn)) {
 			/* Turn off 'trace' bits */
 			regs->msr &= ~MSR_SINGLESTEP;
 			regs->msr |= kcb->kprobe_saved_msr;
 			goto no_kprobe;
 		}
-			/* We have reentered the kprobe_handler(), since
-			 * another probe was hit while within the handler.
-			 * We here save the original kprobes variables and
-			 * just single step on the instruction of the new probe
-			 * without calling any user handlers.
+
+		/*
+		 * We have reentered the kprobe_handler(), since another probe
+		 * was hit while within the handler. We here save the original
+		 * kprobes variables and just single step on the instruction of
+		 * the new probe without calling any user handlers.
 		 */
 		save_previous_kprobe(kcb);
 		set_current_kprobe(p, regs, kcb);
@@ -304,43 +326,6 @@ int kprobe_handler(struct pt_regs *regs)
 		}
 		prepare_singlestep(p, regs);
 		return 1;
-		} else if (*addr != BREAKPOINT_INSTRUCTION) {
-			/* If trap variant, then it belongs not to us */
-			kprobe_opcode_t cur_insn = *addr;
-
-			if (is_trap(cur_insn))
-				goto no_kprobe;
-			/* The breakpoint instruction was removed by
-			 * another cpu right after we hit, no further
-			 * handling of this interrupt is appropriate
-			 */
-			ret = 1;
-		}
-		goto no_kprobe;
-	}
-
-	p = get_kprobe(addr);
-	if (!p) {
-		if (*addr != BREAKPOINT_INSTRUCTION) {
-			/*
-			 * PowerPC has multiple variants of the "trap"
-			 * instruction. If the current instruction is a
-			 * trap variant, it could belong to someone else
-			 */
-			kprobe_opcode_t cur_insn = *addr;
-			if (is_trap(cur_insn))
-				goto no_kprobe;
-			/*
-			 * The breakpoint instruction was removed right
-			 * after we hit it.  Another cpu has removed
-			 * either a probepoint or a debugger breakpoint
-			 * at this address.  In either case, no further
-			 * handling of this interrupt is appropriate.
-			 */
-			ret = 1;
-		}
-		/* Not one of ours: let kernel handle it */
-		goto no_kprobe;
 	}
 
 	kcb->kprobe_status = KPROBE_HIT_ACTIVE;