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sched/task/task_spawn.c: Fix duplicate task_spawn() 

In the FLAT build if CONFIG_LIB_SYSCALL=y, then the function task_spawn() will be duplicated.:  One version in libs/libc/spawn and one version in sched/task.

The version of task_spawn in lib/libc/spawn exists only if CONFIG_LIB_SYSCALL is selected.  In that case, the one in sched/task/task_spawn.c should be static, at least in the FLAT build.

The version of task_spawn.c in libs/libc/spawn simply marshals the parameters into a structure and calls nx_task_spawn().  If CONFIG_LIB_SYSCALL is defined then nx_task_spawn() will un-marshal the data can call the real task spawn.  This nonsense is only necessary because task_spawn has 8 parameters and the maximum number of parameters in a system call is only 6.

Without syscalls:  Application should call directly in task_spawn() in sched/task/task_spawn.c and, hence, it must not be static

With syscalls:  Application should call the marshalling task_spawn() in libs/libc/spawn/lib_task_spawn.c -> That will call the autogenerated nx_task_spawn() proxy -> And generate a system call -> The system call will the unmarshalling nx_task_spawn() in sched/task/task_spawn.c -> Which will, finally, call the real task_spawn().

The side-effect of making task_spawn() static is that it then cannot be used within the OS.  But as far as I can tell, nothing in the OS itself currently uses task_spawn() so I think it is safe to make it conditionally static.  But that only protects from duplicate symbols in the useless case mentioned above.
This commit is contained in:
Gregory Nutt 2020-06-01 07:30:22 -06:00 committed by Abdelatif Guettouche
parent 43183e5843
commit 1041100948
1 changed files with 12 additions and 5 deletions
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17
sched/task/task_spawn.c
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@ -244,7 +244,7 @@ static int nxtask_spawn_proxy(int argc, FAR char *argv[])
****************************************************************************/
/****************************************************************************
* Name: task_spawn
* Name: task_spawn/_task_spawn
*
* Description:
* The task_spawn() function will create a new, child task, where the
@ -308,10 +308,17 @@ static int nxtask_spawn_proxy(int argc, FAR char *argv[])
*
****************************************************************************/
#ifdef CONFIG_LIB_SYSCALL
static int _task_spawn(FAR pid_t *pid, FAR const char *name, main_t entry,
FAR const posix_spawn_file_actions_t *file_actions,
FAR const posix_spawnattr_t *attr,
FAR char * const argv[], FAR char * const envp[])
#else
int task_spawn(FAR pid_t *pid, FAR const char *name, main_t entry,
FAR const posix_spawn_file_actions_t *file_actions,
FAR const posix_spawnattr_t *attr,
FAR char * const argv[], FAR char * const envp[])
#endif
{
struct sched_param param;
pid_t proxy;
@ -441,7 +448,7 @@ errout_with_lock:
* Name: nx_task_spawn
*
* Description:
* This function de-marshals parameters and invokes task_spawn().
* This function de-marshals parameters and invokes _task_spawn().
*
* task_spawn() and posix_spawn() are NuttX OS interfaces. In PROTECTED
* and KERNEL build modes, then can be reached from applications only via
@ -463,9 +470,9 @@ errout_with_lock:
int nx_task_spawn(FAR const struct spawn_syscall_parms_s *parms)
{
DEBUGASSERT(parms != NULL);
return task_spawn(parms->pid, parms->name, parms->entry,
parms->file_actions, parms->attr,
parms->argv, parms->envp);
return _task_spawn(parms->pid, parms->name, parms->entry,
parms->file_actions, parms->attr,
parms->argv, parms->envp);
}
#endif