sparse build breakage with 903c0c7cdc21f2ccb7562a7bbc70289c0c2b16ad

PATCH New Dr. David Alan Gilbert 2 participants 3 messages May 29, 2011 – May 30, 2011

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Dr. David Alan Gilbert

author

2011-05-29 00:39 UTC #0 lore raw

Hi Kosaki,
I'm getting a problem when running the current (5dbe0af47f8a8f968bac2991c3ec974c6e3eaabc)
kernel tree through sparse, and I think it's down to an
interaction between your commit

903c0c7cdc21f2ccb7562a7bbc70289c0c2b16ad sparse: define dummy BUILD_BUG_ON definition for sparse

and the __module_param_call code in moduleparam.h

The error is:
init/main.c:643:1: error: Syntax error in unary expression

core_param(initcall_debug, initcall_debug, bool, 0644);

this calls __module_param_call which is defined as:

#define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
        /* Default value instead of permissions? */                     \
        static int __param_perm_check_##name __attribute__((unused)) =  \
        BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
        + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
        static const char __param_str_##name[] = prefix #name;          \
        static struct kernel_param __moduleparam_const __param_##name   \
        __used                                                          \
    __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
        = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
            { arg } }

which ends up with a postprocessed line of:

static inline void __check_initcall_debug(void) {; }; static int __param_perm_check_initcall_debug __attribute__((unused)) = +; static const char __param_str_initcall_debug[] = "" "initcall_debug"; static struct kernel_param const __param_initcall_debug __attribute__((__used__)) __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) = { __param_str_initcall_debug, &param_ops_bool, 0644, __builtin_types_compatible_p(typeof(initcall_debug), typeof(bool)) ? 2 : 0, { &initcall_debug } };

Note the '+;' being assigned to __param_perm_check_initcall_debug

So I think your dummy BUILD_BUG_ON_ZERO's needs to have a value:

The following diff seems to fix it, but I've not let a fuller sparse run complete yet:

include/linux/kernel.h +2 -2

index fb0e732..953352a 100644
@@ -671,8 +671,8 @@ struct sysinfo {
 
 #ifdef __CHECKER__
 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)
-#define BUILD_BUG_ON_ZERO(e)
-#define BUILD_BUG_ON_NULL(e)
+#define BUILD_BUG_ON_ZERO(e) (0)
+#define BUILD_BUG_ON_NULL(e) ((void*)0)
 #define BUILD_BUG_ON(condition)
 #else /* __CHECKER__ */

Signature · 4 lines

 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\ gro.gilbert @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

KOSAKI Motohiro

Reviewed-by

2011-05-30 01:58 UTC #1 lore raw

Quoted 45 lines · Dr. David Alan Gilbert

Hi Kosaki,
I'm getting a problem when running the current (5dbe0af47f8a8f968bac2991c3ec974c6e3eaabc)
kernel tree through sparse, and I think it's down to an
interaction between your commit
903c0c7cdc21f2ccb7562a7bbc70289c0c2b16ad sparse: define dummy BUILD_BUG_ON definition for sparse
and the __module_param_call code in moduleparam.h
The error is:
init/main.c:643:1: error: Syntax error in unary expression
core_param(initcall_debug, initcall_debug, bool, 0644);
this calls __module_param_call which is defined as:
#define __module_param_call(prefix, name, ops, arg, isbool, perm)       \
        /* Default value instead of permissions? */                     \
        static int __param_perm_check_##name __attribute__((unused)) =  \
        BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2))  \
        + BUILD_BUG_ON_ZERO(sizeof(""prefix) > MAX_PARAM_PREFIX_LEN);   \
        static const char __param_str_##name[] = prefix #name;          \
        static struct kernel_param __moduleparam_const __param_##name   \
        __used                                                          \
    __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) \
        = { __param_str_##name, ops, perm, isbool ? KPARAM_ISBOOL : 0,  \
            { arg } }
which ends up with a postprocessed line of:
static inline void __check_initcall_debug(void) {; }; static int __param_perm_check_initcall_debug __attribute__((unused)) = +; static const char __param_str_initcall_debug[] = "" "initcall_debug"; static struct kernel_param const __param_initcall_debug __attribute__((__used__)) __attribute__ ((unused,__section__ ("__param"),aligned(sizeof(void *)))) = { __param_str_initcall_debug, &param_ops_bool, 0644, __builtin_types_compatible_p(typeof(initcall_debug), typeof(bool)) ? 2 : 0, { &initcall_debug } };
Note the '+;' being assigned to __param_perm_check_initcall_debug
So I think your dummy BUILD_BUG_ON_ZERO's needs to have a value:
The following diff seems to fix it, but I've not let a fuller sparse run complete yet:
include/linux/kernel.h +0 -0
index fb0e732..953352a 100644

include/linux/kernel.h struct sysinfo { · line 678

Quoted 10 lines

include/linux/kernel.h +2 -2

@@ -671,8 +671,8 @@ struct sysinfo {
 
 #ifdef __CHECKER__
 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)
-#define BUILD_BUG_ON_ZERO(e)
-#define BUILD_BUG_ON_NULL(e)
+#define BUILD_BUG_ON_ZERO(e) (0)
+#define BUILD_BUG_ON_NULL(e) ((void*)0)
 #define BUILD_BUG_ON(condition)
 #else /* __CHECKER__ */

Hi David,

Right you are. Can you please send a formal patch and append following line?

Reviewed-by KOSAKI Motohiro <[email protected]>

Thanks.

Dr. David Alan Gilbert

author

2011-05-30 16:04 UTC #2 lore raw

PATCH 1/1 Fix BUILD_BUG_ON_ZERO sparse breakage

BUILD_BUG_ON_ZERO and BUILD_BUG_ON_NULL must return values, even in the CHECKER case otherwise various users of it become syntactically invalid.

Signed-off-by Dr. David Alan Gilbert <[email protected]>

Reviewed-by KOSAKI Motohiro <[email protected]>

---

include/linux/kernel.h +2 -2

index fb0e732..953352a 100644
@@ -671,8 +671,8 @@ struct sysinfo {
 
 #ifdef __CHECKER__
 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)
-#define BUILD_BUG_ON_ZERO(e)
-#define BUILD_BUG_ON_NULL(e)
+#define BUILD_BUG_ON_ZERO(e) (0)
+#define BUILD_BUG_ON_NULL(e) ((void*)0)
 #define BUILD_BUG_ON(condition)
 #else /* __CHECKER__ */