Re: [PATCH 2/2] xen/build: Use C99 booleans

[Julien Grall <julien.grall@arm.com>]

Hi Andrew,

On 14/07/16 16:58, Andrew Cooper wrote:
> and switch bool_t to being of type _Bool rather than char.
>
> Using bool_t as char causes several subtle problems; first that a bool_t
> actually has more than two values, and that (bool_t)0x100 actually has the
> value 0 rather than the expected 1, due to truncation.
>
> Making this change reveals two bugs now caught by the compiler.
> errata_c6_eoi_workaround() actually makes use of bool_t having more than two
> states, while generic_apic_probe() has a integer in the middle of a compound
> bool_t assignment (which triggers a [-Werror=parentheses] warning on Debian
> Jessie).
>
> Finally, it turns out that ARM is mixing and matching bool_t and bool, despite
> their different semantics.  This change brings the semantics of bool_t to
> match bool, but does not alter the current mix.

I will add an item in my todo list to clean-up the ARM code. Is there 
any plan to retire either bool_t or bool?

> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>

 From ARM bits:

Acked-by: Julien Grall <julien.grall@arm.com>

> ---
> CC: Stefano Stabellini <sstabellini@kernel.org>
> CC: Julien Grall <julien.grall@arm.com>
> CC: George Dunlap <George.Dunlap@eu.citrix.com>
> CC: Ian Jackson <ian.jackson@eu.citrix.com>
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> CC: Tim Deegan <tim@xen.org>
> CC: Wei Liu <wei.liu2@citrix.com>
>
> v2:
>   * Leave the matter of std libaries to one side for now.  Fixing bool_t is far
>     more important, and can be done without making the std include issue any
>     worse.
>   * Type tweaks, per v1 review.
> ---
>   xen/arch/arm/p2m.c                   | 1 -
>   xen/arch/arm/platforms/xgene-storm.c | 1 -
>   xen/arch/arm/traps.c                 | 1 -
>   xen/arch/x86/acpi/cpu_idle.c         | 2 +-
>   xen/arch/x86/genapic/probe.c         | 3 ++-
>   xen/include/asm-arm/types.h          | 4 ----
>   xen/include/asm-x86/types.h          | 4 ----
>   xen/include/xen/device_tree.h        | 1 -
>   xen/include/xen/types.h              | 6 ++++++
>   9 files changed, 9 insertions(+), 14 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 976f97b..a4bc55a 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1,7 +1,6 @@
>   #include <xen/config.h>
>   #include <xen/sched.h>
>   #include <xen/lib.h>
> -#include <xen/stdbool.h>
>   #include <xen/errno.h>
>   #include <xen/domain_page.h>
>   #include <xen/bitops.h>
> diff --git a/xen/arch/arm/platforms/xgene-storm.c b/xen/arch/arm/platforms/xgene-storm.c
> index 70cb655..686b19b 100644
> --- a/xen/arch/arm/platforms/xgene-storm.c
> +++ b/xen/arch/arm/platforms/xgene-storm.c
> @@ -20,7 +20,6 @@
>
>   #include <xen/config.h>
>   #include <asm/platform.h>
> -#include <xen/stdbool.h>
>   #include <xen/vmap.h>
>   #include <xen/device_tree.h>
>   #include <asm/io.h>
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 3326122..a2eb1da 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -17,7 +17,6 @@
>    */
>
>   #include <xen/config.h>
> -#include <xen/stdbool.h>
>   #include <xen/init.h>
>   #include <xen/string.h>
>   #include <xen/version.h>
> diff --git a/xen/arch/x86/acpi/cpu_idle.c b/xen/arch/x86/acpi/cpu_idle.c
> index a21aeed..7e235a3 100644
> --- a/xen/arch/x86/acpi/cpu_idle.c
> +++ b/xen/arch/x86/acpi/cpu_idle.c
> @@ -480,7 +480,7 @@ void trace_exit_reason(u32 *irq_traced)
>    */
>   bool_t errata_c6_eoi_workaround(void)
>   {
> -    static bool_t fix_needed = -1;
> +    static int8_t fix_needed = -1;
>
>       if ( unlikely(fix_needed == -1) )
>       {
> diff --git a/xen/arch/x86/genapic/probe.c b/xen/arch/x86/genapic/probe.c
> index a5f2a24..860201e 100644
> --- a/xen/arch/x86/genapic/probe.c
> +++ b/xen/arch/x86/genapic/probe.c
> @@ -56,7 +56,8 @@ custom_param("apic", genapic_apic_force);
>
>   void __init generic_apic_probe(void)
>   {
> -	int i, changed;
> +	bool changed;
> +	int i;
>
>   	record_boot_APIC_mode();
>
> diff --git a/xen/include/asm-arm/types.h b/xen/include/asm-arm/types.h
> index 09e5455..71d2e42 100644
> --- a/xen/include/asm-arm/types.h
> +++ b/xen/include/asm-arm/types.h
> @@ -62,10 +62,6 @@ typedef unsigned long size_t;
>   #endif
>   typedef signed long ssize_t;
>
> -typedef char bool_t;
> -#define test_and_set_bool(b)   xchg(&(b), 1)
> -#define test_and_clear_bool(b) xchg(&(b), 0)
> -
>   #endif /* __ASSEMBLY__ */
>
>   #endif /* __ARM_TYPES_H__ */
> diff --git a/xen/include/asm-x86/types.h b/xen/include/asm-x86/types.h
> index b82fa58..e75b744 100644
> --- a/xen/include/asm-x86/types.h
> +++ b/xen/include/asm-x86/types.h
> @@ -41,10 +41,6 @@ typedef unsigned long size_t;
>   #endif
>   typedef signed long ssize_t;
>
> -typedef char bool_t;
> -#define test_and_set_bool(b)   xchg(&(b), 1)
> -#define test_and_clear_bool(b) xchg(&(b), 0)
> -
>   #endif /* __ASSEMBLY__ */
>
>   #endif /* __X86_TYPES_H__ */
> diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
> index d7d1b40..3657ac2 100644
> --- a/xen/include/xen/device_tree.h
> +++ b/xen/include/xen/device_tree.h
> @@ -17,7 +17,6 @@
>   #include <xen/init.h>
>   #include <xen/string.h>
>   #include <xen/types.h>
> -#include <xen/stdbool.h>
>   #include <xen/list.h>
>
>   #define DEVICE_TREE_MAX_DEPTH 16
> diff --git a/xen/include/xen/types.h b/xen/include/xen/types.h
> index 8596ded..78410de 100644
> --- a/xen/include/xen/types.h
> +++ b/xen/include/xen/types.h
> @@ -1,6 +1,8 @@
>   #ifndef __TYPES_H__
>   #define __TYPES_H__
>
> +#include <xen/stdbool.h>
> +
>   #include <asm/types.h>
>
>   #define BITS_TO_LONGS(bits) \
> @@ -59,4 +61,8 @@ typedef __u64 __be64;
>
>   typedef unsigned long uintptr_t;
>
> +typedef _Bool bool_t;
> +#define test_and_set_bool(b)   xchg(&(b), true)
> +#define test_and_clear_bool(b) xchg(&(b), false)
> +
>   #endif /* __TYPES_H__ */
>

-- 
Julien Grall

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