Skip to content

R
riscv-gcc-1
Commit c0da9742 by Olivier Hainque Committed by Olivier Hainque
Options

vxlib.c: Extract tls related routines into ... 

	* config/vxlib.c: Extract tls related routines into ...
	* config/vxlib-tls.c: New file. 
	* config/t-vxworks: Add vxlib-tls.c to LIB2FUNCS_EXTRA.

From-SVN: r119771
parent 253e0d15
Showing with 8 additions and 298 deletions
gcc/ChangeLog
2006-12-12 Olivier Hainque <hainque@adacore.com>
* config/vxlib.c: Extract tls related routines into ...
* config/vxlib-tls.c: New file.
* config/t-vxworks: Add vxlib-tls.c to LIB2FUNCS_EXTRA.
2006-12-12 Sa Liu <saliu@de.ibm.com>
Ben Elliston <bje@au.ibm.com>
......
gcc/config/t-vxworks
......@@ -11,8 +11,8 @@ TARGET_LIBGCC2_CFLAGS =
# Don't build libgcc.a with debug info
LIBGCC2_DEBUG_CFLAGS =
# Extra libgcc2 module used by gthr-vxworks.h functions
LIB2FUNCS_EXTRA = $(srcdir)/config/vxlib.c
# Extra libgcc2 modules used by gthr-vxworks.h functions
LIB2FUNCS_EXTRA = $(srcdir)/config/vxlib.c $(srcdir)/config/vxlib-tls.c
# Some runtime modules need these. Can't set extra_headers in config.gcc
# because the paths are always made absolute to the cpu config dir.
......
gcc/config/vxlib.c
......@@ -87,300 +87,4 @@ __gthread_once (__gthread_once_t *guard, void (*func)(void))
return 0;
}
/* Thread-local storage.
We reserve a field in the TCB to point to a dynamically allocated
array which is used to store TLS values. A TLS key is simply an
offset in this array. The exact location of the TCB field is not
known to this code nor to vxlib.c -- all access to it indirects
through the routines __gthread_get_tls_data and
__gthread_set_tls_data, which are provided by the VxWorks kernel.
There is also a global array which records which keys are valid and
which have destructors.
A task delete hook is installed to execute key destructors. The
routines __gthread_enter_tls_dtor_context and
__gthread_leave_tls_dtor_context, which are also provided by the
kernel, ensure that it is safe to call free() on memory allocated
by the task being deleted. (This is a no-op on VxWorks 5, but
a major undertaking on AE.)
The task delete hook is only installed when at least one thread
has TLS data. This is a necessary precaution, to allow this module
to be unloaded - a module with a hook can not be removed.
Since this interface is used to allocate only a small number of
keys, the table size is small and static, which simplifies the
code quite a bit. Revisit this if and when it becomes necessary. */
#define MAX_KEYS 4
/* This is the structure pointed to by the pointer returned
by __gthread_get_tls_data. */
struct tls_data
{
int *owner;
void *values[MAX_KEYS];
unsigned int generation[MAX_KEYS];
};
/* To make sure we only delete TLS data associated with this object,
include a pointer to a local variable in the TLS data object. */
static int self_owner;
/* The number of threads for this module which have active TLS data.
This is protected by tls_lock. */
static int active_tls_threads;
/* kernel provided routines */
extern void *__gthread_get_tls_data (void);
extern void __gthread_set_tls_data (void *data);
extern void __gthread_enter_tls_dtor_context (void);
extern void __gthread_leave_tls_dtor_context (void);
/* This is a global structure which records all of the active keys.
A key is potentially valid (i.e. has been handed out by
__gthread_key_create) iff its generation count in this structure is
even. In that case, the matching entry in the dtors array is a
routine to be called when a thread terminates with a valid,
non-NULL specific value for that key.
A key is actually valid in a thread T iff the generation count
stored in this structure is equal to the generation count stored in
T's specific-value structure. */
typedef void (*tls_dtor) (void *);
struct tls_keys
{
tls_dtor dtor[MAX_KEYS];
unsigned int generation[MAX_KEYS];
};
#define KEY_VALID_P(key) !(tls_keys.generation[key] & 1)
/* Note: if MAX_KEYS is increased, this initializer must be updated
to match. All the generation counts begin at 1, which means no
key is valid. */
static struct tls_keys tls_keys =
{
{ 0, 0, 0, 0 },
{ 1, 1, 1, 1 }
};
/* This lock protects the tls_keys structure. */
static __gthread_mutex_t tls_lock;
static __gthread_once_t tls_init_guard = __GTHREAD_ONCE_INIT;
/* Internal routines. */
/* The task TCB has just been deleted. Call the destructor
function for each TLS key that has both a destructor and
a non-NULL specific value in this thread.
This routine does not need to take tls_lock; the generation
count protects us from calling a stale destructor. It does
need to read tls_keys.dtor[key] atomically. */
static void
tls_delete_hook (void *tcb ATTRIBUTE_UNUSED)
{
struct tls_data *data = __gthread_get_tls_data ();
__gthread_key_t key;
if (data && data->owner == &self_owner)
{
__gthread_enter_tls_dtor_context ();
for (key = 0; key < MAX_KEYS; key++)
{
if (data->generation[key] == tls_keys.generation[key])
{
tls_dtor dtor = tls_keys.dtor[key];
if (dtor)
dtor (data->values[key]);
}
}
free (data);
/* We can't handle an error here, so just leave the thread
marked as loaded if one occurs. */
if (__gthread_mutex_lock (&tls_lock) != ERROR)
{
active_tls_threads--;
if (active_tls_threads == 0)
taskDeleteHookDelete ((FUNCPTR)tls_delete_hook);
__gthread_mutex_unlock (&tls_lock);
}
__gthread_set_tls_data (0);
__gthread_leave_tls_dtor_context ();
}
}
/* Initialize global data used by the TLS system. */
static void
tls_init (void)
{
__GTHREAD_MUTEX_INIT_FUNCTION (&tls_lock);
}
static void tls_destructor (void) __attribute__ ((destructor));
static void
tls_destructor (void)
{
#ifdef __RTP__
/* All threads but this one should have exited by now. */
tls_delete_hook (NULL);
#else
/* Unregister the hook forcibly. The counter of active threads may
be incorrect, because constructors (like the C++ library's) and
destructors (like this one) run in the context of the shell rather
than in a task spawned from this module. */
taskDeleteHookDelete ((FUNCPTR)tls_delete_hook);
#endif
if (tls_init_guard.done && __gthread_mutex_lock (&tls_lock) != ERROR)
semDelete (tls_lock);
}
/* External interface */
/* Store in KEYP a value which can be passed to __gthread_setspecific/
__gthread_getspecific to store and retrieve a value which is
specific to each calling thread. If DTOR is not NULL, it will be
called when a thread terminates with a non-NULL specific value for
this key, with the value as its sole argument. */
int
__gthread_key_create (__gthread_key_t *keyp, tls_dtor dtor)
{
__gthread_key_t key;
__gthread_once (&tls_init_guard, tls_init);
if (__gthread_mutex_lock (&tls_lock) == ERROR)
return errno;
for (key = 0; key < MAX_KEYS; key++)
if (!KEY_VALID_P (key))
goto found_slot;
/* no room */
__gthread_mutex_unlock (&tls_lock);
return EAGAIN;
found_slot:
tls_keys.generation[key]++; /* making it even */
tls_keys.dtor[key] = dtor;
*keyp = key;
__gthread_mutex_unlock (&tls_lock);
return 0;
}
/* Invalidate KEY; it can no longer be used as an argument to
setspecific/getspecific. Note that this does NOT call destructor
functions for any live values for this key. */
int
__gthread_key_delete (__gthread_key_t key)
{
if (key >= MAX_KEYS)
return EINVAL;
__gthread_once (&tls_init_guard, tls_init);
if (__gthread_mutex_lock (&tls_lock) == ERROR)
return errno;
if (!KEY_VALID_P (key))
{
__gthread_mutex_unlock (&tls_lock);
return EINVAL;
}
tls_keys.generation[key]++; /* making it odd */
tls_keys.dtor[key] = 0;
__gthread_mutex_unlock (&tls_lock);
return 0;
}
/* Retrieve the thread-specific value for KEY. If it has never been
set in this thread, or KEY is invalid, returns NULL.
It does not matter if this function races with key_create or
key_delete; the worst that can happen is you get a value other than
the one that a serialized implementation would have provided. */
void *
__gthread_getspecific (__gthread_key_t key)
{
struct tls_data *data;
if (key >= MAX_KEYS)
return 0;
data = __gthread_get_tls_data ();
if (!data)
return 0;
if (data->generation[key] != tls_keys.generation[key])
return 0;
return data->values[key];
}
/* Set the thread-specific value for KEY. If KEY is invalid, or
memory allocation fails, returns -1, otherwise 0.
The generation count protects this function against races with
key_create/key_delete; the worst thing that can happen is that a
value is successfully stored into a dead generation (and then
immediately becomes invalid). However, we do have to make sure
to read tls_keys.generation[key] atomically. */
int
__gthread_setspecific (__gthread_key_t key, void *value)
{
struct tls_data *data;
unsigned int generation;
if (key >= MAX_KEYS)
return EINVAL;
data = __gthread_get_tls_data ();
if (!data)
{
if (__gthread_mutex_lock (&tls_lock) == ERROR)
return ENOMEM;
if (active_tls_threads == 0)
taskDeleteHookAdd ((FUNCPTR)tls_delete_hook);
active_tls_threads++;
__gthread_mutex_unlock (&tls_lock);
data = malloc (sizeof (struct tls_data));
if (!data)
return ENOMEM;
memset (data, 0, sizeof (struct tls_data));
data->owner = &self_owner;
__gthread_set_tls_data (data);
}
generation = tls_keys.generation[key];
if (generation & 1)
return EINVAL;
data->generation[key] = generation;
data->values[key] = value;
return 0;
}
#endif /* __GTHREADS */
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment