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elf: Add a way to check if tunable is set (BZ 27069)

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The patch adds two new macros, TUNABLE_GET_DEFAULT and TUNABLE_IS_INITIALIZED,
here the former get the default value with a signature similar to
TUNABLE_GET, while the later returns whether the tunable was set by
the environment variable.

Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
This commit is contained in:
Adhemerval Zanella
2023-11-23 14:29:14 -03:00
parent 9469261cf1
commit a4c3f5f46e
6 changed files with 73 additions and 2 deletions
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28
elf/dl-tunables.h
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@@ -45,18 +45,26 @@ typedef void (*tunable_callback_t) (tunable_val_t *);
extern void __tunables_init (char **);
extern void __tunables_print (void);
extern bool __tunable_is_initialized (tunable_id_t);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
extern void __tunable_set_val (tunable_id_t, tunable_val_t *, tunable_num_t *,
tunable_num_t *);
extern void __tunable_get_default (tunable_id_t id, void *valp);
rtld_hidden_proto (__tunables_init)
rtld_hidden_proto (__tunables_print)
rtld_hidden_proto (__tunable_is_initialized)
rtld_hidden_proto (__tunable_get_val)
rtld_hidden_proto (__tunable_set_val)
rtld_hidden_proto (__tunable_get_default)
/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
tunables within a module. */
#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
# define TUNABLE_IS_INITIALIZED(__id) \
TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id)
# define TUNABLE_GET_DEFAULT(__id, __type) \
TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type)
# define TUNABLE_GET(__id, __type, __cb) \
TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
# define TUNABLE_SET(__id, __val) \
@@ -65,6 +73,10 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
__val, __min, __max)
#else
# define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \
TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id)
# define TUNABLE_GET_DEFAULT(__top, __ns, __type) \
TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type)
# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
# define TUNABLE_SET(__top, __ns, __id, __val) \
@@ -73,6 +85,22 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
#endif
/* Return whether the tunable was initialized by the environment variable. */
#define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \
({ \
tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
__tunable_is_initialized (id); \
})
/* Return the default value of the tunable. */
#define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \
({ \
tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
__type __ret; \
__tunable_get_default (id, &__ret); \
__ret; \
})
/* Get and return a tunable value. If the tunable was set externally and __CB
is defined then call __CB before returning the value. */
#define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \