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Re: [Qemu-ppc] [PATCH 3/3] maint: Fix macros with broken 'do/while(0); '
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-ppc] [PATCH 3/3] maint: Fix macros with broken 'do/while(0); ' usage |
Date: |
Thu, 30 Nov 2017 14:54:46 +0100 |
On Thu, 30 Nov 2017 07:41:59 -0600
Eric Blake <address@hidden> wrote:
> The point of writing a macro embedded in a 'do { ... } while (0)'
> loop is so that the macro can be used as a drop-in statement with
> the caller supplying the trailing ';'. Although our coding style
> frowns on brace-less 'if':
> if (cond)
> statement;
> else
> something else;
> the use of do/while (0) in a macro is absolutely essential for the
> purpose of avoiding a syntax error on the 'else' - but it only works
> if there is no trailing ';' in the macro (as the ';' in the code
> calling the macro would then be a second statement and cause the
> 'else' to not pair to the 'if').
>
> Many of the places touched in this code are examples of the ugly
> bit-rotting debug print statements; cleaning those up is left as
> a bite-sized task for another day.
>
> Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\
>
> Signed-off-by: Eric Blake <address@hidden>
> ---
> tests/acpi-utils.h | 8 ++++----
> ui/sdl_zoom_template.h | 8 ++++----
> audio/paaudio.c | 4 ++--
> hw/adc/stm32f2xx_adc.c | 2 +-
> hw/block/m25p80.c | 2 +-
> hw/char/cadence_uart.c | 2 +-
> hw/char/stm32f2xx_usart.c | 2 +-
> hw/display/cg3.c | 2 +-
> hw/display/dpcd.c | 2 +-
> hw/display/xlnx_dp.c | 2 +-
> hw/dma/pl330.c | 2 +-
> hw/dma/xlnx-zynq-devcfg.c | 2 +-
> hw/dma/xlnx_dpdma.c | 2 +-
> hw/i2c/i2c-ddc.c | 2 +-
> hw/misc/auxbus.c | 2 +-
> hw/misc/macio/mac_dbdma.c | 4 ++--
> hw/misc/mmio_interface.c | 2 +-
> hw/misc/stm32f2xx_syscfg.c | 2 +-
> hw/misc/zynq_slcr.c | 2 +-
> hw/net/cadence_gem.c | 2 +-
> hw/ssi/mss-spi.c | 2 +-
> hw/ssi/stm32f2xx_spi.c | 2 +-
> hw/ssi/xilinx_spi.c | 2 +-
> hw/ssi/xilinx_spips.c | 2 +-
> hw/timer/a9gtimer.c | 2 +-
> hw/timer/cadence_ttc.c | 2 +-
> hw/timer/mss-timer.c | 2 +-
> hw/timer/stm32f2xx_timer.c | 2 +-
> hw/tpm/tpm_passthrough.c | 2 +-
> hw/tpm/tpm_tis.c | 2 +-
> migration/rdma.c | 2 +-
> target/arm/translate-a64.c | 2 +-
> target/s390x/kvm.c | 2 +-
> tests/tcg/test-mmap.c | 2 +-
> 34 files changed, 42 insertions(+), 42 deletions(-)
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index b03f583032..06d06010a4 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -58,7 +58,7 @@
> if (DEBUG_KVM) { \
> fprintf(stderr, fmt, ## __VA_ARGS__); \
> } \
> -} while (0);
> +} while (0)
>
> #define kvm_vm_check_mem_attr(s, attr) \
> kvm_vm_check_attr(s, KVM_S390_VM_MEM_CTRL, attr)
Acked-by: Cornelia Huck <address@hidden>