Merge tag 'Wimplicit-fallthrough-clang-5.14-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull fallthrough fixes from Gustavo Silva:
 "This fixes many fall-through warnings when building with Clang and
  -Wimplicit-fallthrough, and also enables -Wimplicit-fallthrough for
  Clang, globally.

  It's also important to notice that since we have adopted the use of
  the pseudo-keyword macro fallthrough, we also want to avoid having
  more /* fall through */ comments being introduced. Contrary to GCC,
  Clang doesn't recognize any comments as implicit fall-through markings
  when the -Wimplicit-fallthrough option is enabled.

  So, in order to avoid having more comments being introduced, we use
  the option -Wimplicit-fallthrough=5 for GCC, which similar to Clang,
  will cause a warning in case a code comment is intended to be used as
  a fall-through marking. The patch for Makefile also enforces this.

  We had almost 4,000 of these issues for Clang in the beginning, and
  there might be a couple more out there when building some
  architectures with certain configurations. However, with the recent
  fixes I think we are in good shape and it is now possible to enable
  the warning for Clang"

* tag 'Wimplicit-fallthrough-clang-5.14-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (27 commits)
  Makefile: Enable -Wimplicit-fallthrough for Clang
  powerpc/smp: Fix fall-through warning for Clang
  dmaengine: mpc512x: Fix fall-through warning for Clang
  usb: gadget: fsl_qe_udc: Fix fall-through warning for Clang
  powerpc/powernv: Fix fall-through warning for Clang
  MIPS: Fix unreachable code issue
  MIPS: Fix fall-through warnings for Clang
  ASoC: Mediatek: MT8183: Fix fall-through warning for Clang
  power: supply: Fix fall-through warnings for Clang
  dmaengine: ti: k3-udma: Fix fall-through warning for Clang
  s390: Fix fall-through warnings for Clang
  dmaengine: ipu: Fix fall-through warning for Clang
  iommu/arm-smmu-v3: Fix fall-through warning for Clang
  mmc: jz4740: Fix fall-through warning for Clang
  PCI: Fix fall-through warning for Clang
  scsi: libsas: Fix fall-through warning for Clang
  video: fbdev: Fix fall-through warning for Clang
  math-emu: Fix fall-through warning
  cpufreq: Fix fall-through warning for Clang
  drm/msm: Fix fall-through warning in msm_gem_new_impl()
  ...

Author: torvalds

Makefile

@@ -797,12 +797,6 @@ KBUILD_CFLAGS += -Wno-gnu
 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
 # See modpost pattern 2
 KBUILD_CFLAGS += -mno-global-merge
-else
-
-# Warn about unmarked fall-throughs in switch statement.
-# Disabled for clang while comment to attribute conversion happens and
-# https://github.com/ClangBuiltLinux/linux/issues/636 is discussed.
-KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough,)
 endif
 
 # These warnings generated too much noise in a regular build.
@@ -983,6 +977,9 @@ NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
 # warn about C99 declaration after statement
 KBUILD_CFLAGS += -Wdeclaration-after-statement
 
+# Warn about unmarked fall-throughs in switch statement.
+KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough=5,$(call cc-option,-Wimplicit-fallthrough,))
+
 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
 KBUILD_CFLAGS += -Wvla
 

arch/mips/include/asm/fpu.h

@@ -76,7 +76,7 @@ static inline int __enable_fpu(enum fpu_mode mode)
 		/* we only have a 32-bit FPU */
 		return SIGFPE;
 #endif
-		fallthrough;
+		/* fallthrough */
 	case FPU_32BIT:
 		if (cpu_has_fre) {
 			/* clear FRE */

arch/mips/mm/tlbex.c

@@ -1383,6 +1383,7 @@ static void build_r4000_tlb_refill_handler(void)
 	switch (boot_cpu_type()) {
 	default:
 		if (sizeof(long) == 4) {
+		fallthrough;
 	case CPU_LOONGSON2EF:
 		/* Loongson2 ebase is different than r4k, we have more space */
 			if ((p - tlb_handler) > 64)
@@ -2169,6 +2170,7 @@ static void build_r4000_tlb_load_handler(void)
 		default:
 			if (cpu_has_mips_r2_exec_hazard) {
 				uasm_i_ehb(&p);
+			fallthrough;
 
 		case CPU_CAVIUM_OCTEON:
 		case CPU_CAVIUM_OCTEON_PLUS:

arch/powerpc/platforms/powermac/smp.c

@@ -146,6 +146,7 @@ static inline void psurge_clr_ipi(int cpu)
 		switch(psurge_type) {
 		case PSURGE_DUAL:
 			out_8(psurge_sec_intr, ~0);
+			break;
 		case PSURGE_NONE:
 			break;
 		default:

arch/s390/kernel/uprobes.c

@@ -126,6 +126,7 @@ int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
 	case DIE_SSTEP:
 		if (uprobe_post_sstep_notifier(regs))
 			return NOTIFY_STOP;
+		break;
 	default:
 		break;
 	}

drivers/char/powernv-op-panel.c

@@ -75,6 +75,7 @@ static int __op_panel_update_display(void)
 				rc);
 			break;
 		}
+		break;
 	case OPAL_SUCCESS:
 		break;
 	default:

drivers/cpufreq/longhaul.c

@@ -942,8 +942,6 @@ static int __init longhaul_init(void)
 		return cpufreq_register_driver(&longhaul_driver);
 	case 10:
 		pr_err("Use acpi-cpufreq driver for VIA C7\n");
-	default:
-		;
 	}
 
 	return -ENODEV;

drivers/dma/ipu/ipu_idmac.c

@@ -618,6 +618,7 @@ static int ipu_enable_channel(struct idmac *idmac, struct idmac_channel *ichan)
 	case IDMAC_SDC_1:
 	case IDMAC_IC_7:
 		ipu_channel_set_priority(ipu, channel, true);
+		break;
 	default:
 		break;
 	}
@@ -978,6 +979,7 @@ static int ipu_init_channel(struct idmac *idmac, struct idmac_channel *ichan)
 	case IDMAC_SDC_0:
 	case IDMAC_SDC_1:
 		n_desc = 4;
+		break;
 	default:
 		break;
 	}

drivers/dma/mpc512x_dma.c

@@ -813,6 +813,7 @@ inline bool is_buswidth_valid(u8 buswidth, bool is_mpc8308)
 	case 16:
 		if (is_mpc8308)
 			return false;
+		break;
 	case 1:
 	case 2:
 	case 4:

drivers/dma/ti/k3-udma.c

@@ -4948,6 +4948,7 @@ static int setup_resources(struct udma_dev *ud)
 						       ud->tchan_cnt),
 			 ud->rchan_cnt - bitmap_weight(ud->rchan_map,
 						       ud->rchan_cnt));
+		break;
 	default:
 		break;
 	}