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posix: replace mmap mappings lock with libio lock

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Use the libio mutex lock instead of the mmap mappings lock.

Updates #2859.
This commit is contained in:
Gedare Bloom
2017-07-24 14:46:49 -04:00
parent 1c256e6fbe
commit b264998fa9
3 changed files with 13 additions and 86 deletions
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11
cpukit/posix/include/rtems/posix/mmanimpl.h
View File

@@ -39,8 +39,15 @@ typedef struct mmap_mappings_s {
extern rtems_chain_control mmap_mappings;
bool mmap_mappings_lock_obtain( void );
bool mmap_mappings_lock_release( void );
static inline void mmap_mappings_lock_obtain( void )
{
rtems_libio_lock();
}
static inline void mmap_mappings_lock_release( void )
{
rtems_libio_unlock();
}
#ifdef __cplusplus
}

82
cpukit/posix/src/mmap.c
View File

@@ -28,85 +28,11 @@
#include <rtems/posix/mmanimpl.h>
#include <rtems/posix/shmimpl.h>
#define RTEMS_MUTEX_ATTRIBS \
(RTEMS_PRIORITY | RTEMS_SIMPLE_BINARY_SEMAPHORE | \
RTEMS_NO_INHERIT_PRIORITY | RTEMS_NO_PRIORITY_CEILING | RTEMS_LOCAL)
/**
* Mmap chain of mappings.
* mmap chain of mappings.
*/
rtems_chain_control mmap_mappings;
/**
* The id of the MMAP lock.
*/
static rtems_id mmap_mappings_lock;
/**
* Create the lock.
*/
static
bool mmap_mappings_lock_create(
void
)
{
/*
* Lock the mapping table. We only create a lock if a call is made. First we
* test if a mapping lock is present. If one is present we lock it. If not
* the libio lock is locked and we then test the mapping lock again. If not
* present we create the mapping lock then release libio lock.
*/
/* FIXME: double-checked locking anti-pattern. */
if ( mmap_mappings_lock == 0 ) {
rtems_status_code sc = RTEMS_SUCCESSFUL;
rtems_chain_initialize_empty( &mmap_mappings );
rtems_semaphore_obtain( rtems_libio_semaphore,
RTEMS_WAIT, RTEMS_NO_TIMEOUT );
/* FIXME: account for semaphore in confdefs, or maybe just use the
* rtems_libio_semaphore? */
if ( mmap_mappings_lock == 0 )
sc = rtems_semaphore_create( rtems_build_name( 'M', 'M', 'A', 'P' ),
1,
RTEMS_MUTEX_ATTRIBS,
RTEMS_NO_PRIORITY,
&mmap_mappings_lock );
rtems_semaphore_release( rtems_libio_semaphore );
if ( sc != RTEMS_SUCCESSFUL ) {
errno = EINVAL;
return false;
}
}
return true;
}
bool mmap_mappings_lock_obtain(
void
)
{
if ( mmap_mappings_lock_create( ) ) {
rtems_status_code sc;
sc = rtems_semaphore_obtain( mmap_mappings_lock,
RTEMS_WAIT, RTEMS_NO_TIMEOUT );
if ( sc != RTEMS_SUCCESSFUL ) {
errno = EINVAL;
return false;
}
}
return true;
}
bool mmap_mappings_lock_release(
void
)
{
rtems_status_code sc;
sc = rtems_semaphore_release( mmap_mappings_lock );
if (( sc != RTEMS_SUCCESSFUL ) && ( errno == 0 )) {
errno = EINVAL;
return false;
}
return true;
}
CHAIN_DEFINE_EMPTY( mmap_mappings );
void *mmap(
void *addr, size_t len, int prot, int flags, int fildes, off_t off
@@ -307,9 +233,7 @@ void *mmap(
return MAP_FAILED;
}
/* Lock access to mmap_mappings. Sets errno on failure. */
if ( !mmap_mappings_lock_obtain( ) )
return MAP_FAILED;
mmap_mappings_lock_obtain();
if ( map_fixed ) {
rtems_chain_node* node = rtems_chain_first (&mmap_mappings);

6
cpukit/posix/src/munmap.c
View File

@@ -52,11 +52,7 @@ int munmap(void *addr, size_t len)
return -1;
}
/*
* Obtain the mmap lock. Sets errno on failure.
*/
if ( !mmap_mappings_lock_obtain( ))
return -1;
mmap_mappings_lock_obtain();
node = rtems_chain_first (&mmap_mappings);
while ( !rtems_chain_is_tail( &mmap_mappings, node )) {