linux-kernel - Re: [PATCH v2] powerpc/32: sstep: Move variable `rc` within CONFIG

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Date:   Tue, 28 May 2019 21:40:34 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Mathieu Malaterre <malat@...ian.org>
Cc:     Mathieu Malaterre <malat@...ian.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] powerpc/32: sstep: Move variable `rc` within CONFIG_PPC64 sentinels

Mathieu Malaterre <malat@...ian.org> writes:

> Fix warnings treated as errors with W=1:
>
>   arch/powerpc/lib/sstep.c:1172:31: error: variable 'rc' set but not used [-Werror=unused-but-set-variable]
>
> Suggested-by: Christophe Leroy <christophe.leroy@....fr>
> Signed-off-by: Mathieu Malaterre <malat@...ian.org>
> ---
> v2: as suggested prefer CONFIG_PPC64 sentinel instead of unused keyword

I'd rather avoid adding more ifdefs if we can.

I think this works?

cheers

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 3d33fb509ef4..600b036ddfda 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1169,7 +1169,7 @@ static nokprobe_inline int trap_compare(long v1, long v2)
 int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		  unsigned int instr)
 {
-	unsigned int opcode, ra, rb, rc, rd, spr, u;
+	unsigned int opcode, ra, rb, rd, spr, u;
 	unsigned long int imm;
 	unsigned long int val, val2;
 	unsigned int mb, me, sh;
@@ -1292,7 +1292,6 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 	rd = (instr >> 21) & 0x1f;
 	ra = (instr >> 16) & 0x1f;
 	rb = (instr >> 11) & 0x1f;
-	rc = (instr >> 6) & 0x1f;
 
 	switch (opcode) {
 #ifdef __powerpc64__
@@ -1307,10 +1306,14 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		return 1;
 
 #ifdef __powerpc64__
-	case 4:
+	case 4: {
+		unsigned int rc;
+
 		if (!cpu_has_feature(CPU_FTR_ARCH_300))
 			return -1;
 
+		rc = (instr >> 6) & 0x1f;
+
 		switch (instr & 0x3f) {
 		case 48:	/* maddhd */
 			asm volatile(PPC_MADDHD(%0, %1, %2, %3) :
@@ -1336,6 +1339,7 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
 		 * primary opcode which do not have emulation support yet.
 		 */
 		return -1;
+	}
 #endif
 
 	case 7:		/* mulli */